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DIY - Red Tek conversion
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Howesight
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PostPosted: Fri Jul 26, 2019 1:50 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Hey Snowave:

Given the ambient temps of 105F in the shade, I agree with one of the posters above that it will take time to cool your interior. The factory Vanagon system is a recirculating system which does not draw outside air into the AC system.

BUT, the front grille and air handler does allow many CFM's of ambient air into the vehicle if you do not seal it off. Chris Corkins of Vanistan has a device that cures this:

https://intrepidoverland.com/shop/cabin-air-control/

Years ago, I made my own crude device to achieve the same goal.

In a pinch, until your Vanistan unit arrives, you can apply duct tape over the screen that covers the fresh air intake. I highly recommend this kludge so that you can test the real ability of your AC system.

Three other points I can make:

1. An awful lot of RedTek (or any refrigerant) can end up lost in your gauge set hoses. Regardless, try releasing some of the RedTek refrigerant (from the low side, with gloves and safety glasses) until you get the low-side pressures to around 30 to 33 psi, watching your vent temps as you go.

2. Air brake line drier is okay for cleaning AC lines and parts, but it does not vaporize out of the system as quickly or effectively as the expensive dedicated flush solvents. This is fine as long as you run compressed air through the flushed parts for long enough to vaporize all the air brake drier out of the various parts.

3. The pressures you list do not indicate that the Thermal Expansion Valve is malfunctioning, which is a good sign that there is not enough water in your system to affect the TXV.
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PostPosted: Wed Jul 31, 2019 9:12 am    Post subject: Re: DIY - Red Tek conversion Reply with quote

This isn't exactly a conversion question, but I'm want to make sure I'm recharging the system correctly since I'm kind of a newbie at this. I do know enough to wear gloves and glasses. Our 1990 Westy AC was converted to redtek about 9 years ago with most components replaced. It worked pretty well since then, although I would need to top it off every two years or so to get it to blow cool again. Last weekend I went to top it off, and all went fine, until I disconnected the low side and the schrader valve failed releasing all pressure. So I need to recharge it, and here are my plans:

1. Replace low side fitting and valve with Santech replacement.
2. Get loaner electric vacuum and gauge set from Autozone, pull a vacuum on the system for a couple hours, and make sure it holds overnight.
3. With engine off, recharge with one can of Redtek turned upside down into low side port until ~20-30 PSI is achieved.
4. Box fan at front grille, start engine, turn on AC to highest setting, add ~3 more cans of Redtek until ~40 PSI is achieved at the low side and/or it's blowing cold again.

Does this sound about right? Anything I'm missing?
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PostPosted: Wed Jul 31, 2019 2:01 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Be sure & bleed the air out of the gauge set yellow hose. After connecting to the refrigerant can & opening the can tap valve, loosen the yellow hose connection at the gauge manifold so the air can be forced out. You don't want to pull this air into the system. Other than that, your proceedure sounds right. One item of note...did you put the cap back on the low side fitting to keep excess moisture out of the system. It helps keep the dryer desiccant from getting saturated.....Good luck & Keep Cool!
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PostPosted: Wed Jul 31, 2019 6:49 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

[quote="Howesight"]
1. An awful lot of RedTek (or any refrigerant) can end up lost in your gauge set hoses. Regardless, try releasing some of the RedTek refrigerant (from the low side, with gloves and safety glasses) until you get the low-side pressures to around 30 to 33 psi, watching your vent temps as you go.

Thanks Howesight, I will give this a try.
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grambo
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PostPosted: Thu Aug 01, 2019 7:34 am    Post subject: Re: DIY - Red Tek conversion Reply with quote

VWagabond wrote:
Be sure & bleed the air out of the gauge set yellow hose....One item of note...did you put the cap back on the low side fitting to keep excess moisture out of the system. It helps keep the dryer desiccant from getting saturated.....Good luck & Keep Cool!


Thanks for the tips VWagabond! Yeah I definitely put the cap back on hoping to keep out as much air/moisture as possible. Previously I was topping off with the funky little valve and gauge that came with the redtek kit, so this will be my first time using a real manifold gauge set. Always trying, sometimes failing, but always learning!
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bettingonvans
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PostPosted: Wed May 06, 2020 9:23 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

My Red Tek rebuild works! But I am hoping for a little guidance.

I charged with Red Tek and while holding idle at the throttle body of 2000 RPM I see high-side pressures of about 190-200, and low-side pressures of 26-29. That's at 75-80F ambient temp with about 3-3.5 cans of Red Tek installed. I am unsure exactly how much refrigerant I have put in because of some trouble I had with a borrowed set of manifold gauges.

The performance seems okay. After a 20min drive with A/C on and fan on high, my vent temps were about 43 or 44F. My understanding is that I may see lower temps if I experiment with a lower fan speed, I have only observed the temperature on high fan speed, but I have run it with very low speed with the evaporator uncovered and I can certainly say that it would freeze up given enough time with insufficient airflow.

I have not had the chance to optimize, but I suspect I may be under-charged, because while running steadily at 2000 RPM, the low-side pressure will intermittently drop from its 26-29 PSI down to as low as 10 psi and then ramp back up over the duration of maybe 5-10 seconds and then go on at 26-29 PSI until it periodically repeats. Does anyone have any idea as to the cause of this? The compressor remains on the entire time and the high-side pressure does not fluctuate, remaining between 190 and 200 psi.

I completely restored my A/C system following guidance from the threads that Dave and cellardoor started. New Sanden compressor, parallel flow condenser, expansion valve, drier, hoses, fittings, trinary switch and whatever else I am forgetting now.

Does anyone have any thoughts as to why my low-side might be fluctuating, with the system performing mostly well, though not yet optimized?
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PostPosted: Fri Nov 20, 2020 1:51 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

As a new Vanagon owner and an old AC pro, I am reading a ton of frustrations here.

There is a definitive answer on charging and converting systems:

If you are changing oil from Mineral to polyol ester (POE) with a system that has no refrigerant in it:
1. You must replace the compressor and filter dryer.
2. You must flush the refrigerant lines, evaporator and condenser. I use R-11 flush (because I'm a pro and can get it). You may use the items listed here by various folks with different results.
3. Replace the TXV with the matching refrigerant and size of unit if you are changing refrigerants.
4. Pressurize the system with dry nitrogen to remove any non-condensables and determine if there are any leaks in the system. Pressurize to 160psi of dry nitrogen and use soap bubbles on all fittings and where rubber meets metal. Tighten or reseal any leaking fittings, replace any worn hoses (or repair if you have the means) and replace any components that leak refrigerant (nitrogen). If the system holds 160 psi for more than an hour you likely don't have a leak anymore.
5. Evacuate with proper vacuum pump using a micron guage at the end of your vacuum cycle. micron guage to 500 and hold is perfection. Sea level vehicles will go lower, but I'm in Colorado so thats my benchmark. While the system is pulling down in a vacuum, clean up your work area. If you don't have 500 microns, YOU HAVE A LEAK. Go back to step 4
6. After proving 500 microns, charge the system with the recommended
80% of refrigerant charge.
7. Cycle the system to move refrigerant around. add the remaining 20% of charge while the unit is operating.


If you are not changing oil: Start at step 4 unless there is a known problem
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PostPosted: Fri Nov 20, 2020 2:40 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

bettingonvans wrote:


Does anyone have any thoughts as to why my low-side might be fluctuating, with the system performing mostly well, though not yet optimized?


The TXV is hunting because the charge is a tad bit low. I would leave it where its at as I like a colder discharge air temp. If you notice any freezing on the suction line to the compressor, add a little bit more refrigerant.
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PostPosted: Fri Nov 20, 2020 6:20 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

fatherdonz wrote:
As a new Vanagon owner and an old AC pro, I am reading a ton of frustrations here.

There is a definitive answer on charging and converting systems:

If you are changing oil from Mineral to polyol ester (POE) with a system that has no refrigerant in it:
1. You must replace the compressor and filter dryer.
2. You must flush the refrigerant lines, evaporator and condenser. I use R-11 flush (because I'm a pro and can get it). You may use the items listed here by various folks with different results.
3. Replace the TXV with the matching refrigerant and size of unit if you are changing refrigerants.
4. Pressurize the system with dry nitrogen to remove any non-condensables and determine if there are any leaks in the system. Pressurize to 160psi of dry nitrogen and use soap bubbles on all fittings and where rubber meets metal. Tighten or reseal any leaking fittings, replace any worn hoses (or repair if you have the means) and replace any components that leak refrigerant (nitrogen). If the system holds 160 psi for more than an hour you likely don't have a leak anymore.
5. Evacuate with proper vacuum pump using a micron guage at the end of your vacuum cycle. micron guage to 500 and hold is perfection. Sea level vehicles will go lower, but I'm in Colorado so thats my benchmark. While the system is pulling down in a vacuum, clean up your work area. If you don't have 500 microns, YOU HAVE A LEAK. Go back to step 4
6. After proving 500 microns, charge the system with the recommended
80% of refrigerant charge.
7. Cycle the system to move refrigerant around. add the remaining 20% of charge while the unit is operating.


If you are not changing oil: Start at step 4 unless there is a known problem


^^^Sounds like I know who to take my van to in the spring.
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PostPosted: Sun Jun 20, 2021 7:46 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

I've read many pages of this and other threads, most of them haven't been updated in a couple of years. Maybe this should go under another thread, but...it appears the RedTek is no longer selling the same refrigerant this thread started out with. is there another product you fine folks prefer these days, either sold be RedTek or another company?
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Howesight
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PostPosted: Sun Jun 20, 2021 9:36 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

I think that RedTek is a Canadian product (I could be wrong) as I see it in any auto parts section up here, but see many Americans unable to find it.

There is no particular magic to RedTek - - it is a butane-based hydrocarbon mixture. Its refrigerant properties mimic R-12, which is why it works so well in service. Any of the other hydro-carbon based refrigerants can be used instead of RedTek applying all the advice you see in the thread above. The "magic" of ReTek is that they did their homework with testing and publishing their fill data and R-12, R-134A conversion weights and pressures. You could probably use all the data they have posted for any of the competitor products found in the USA.

Best of luck!
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PostPosted: Sun Jun 20, 2021 10:44 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Propane and iso-butane will provide a very close approximation of R-12 without all the fuss n' muss. Straight propane will resurrect a dead A/C system simply because it has the properties needed for a gas exchange. I would resurrect R-134a systems the same way, but I don't yet have the adapters for their fill ports.
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PostPosted: Fri Jun 25, 2021 7:33 am    Post subject: Re: DIY - Red Tek conversion Reply with quote

73thingsale wrote:
I've read many pages of this and other threads, most of them haven't been updated in a couple of years. Maybe this should go under another thread, but...it appears the RedTek is no longer selling the same refrigerant this thread started out with. is there another product you fine folks prefer these days, either sold be RedTek or another company?



I just recharged my system with a 3 can kit of Redtek R-12a and no leakstop from redtekstore.com. You might look there, shipping was pretty quick.

Redtek works like a dream, as others have said. The PO had already converted to R-134a and it had all leaked out so I didn't have to worry about having anything professionally extracted. I changed the drier and some easy to reach gaskets, borrowed a vacuum and a manifold from my FLAPs for free and put in about 2.3 cans worth before I hit target pressure (it was a hot day and I didn't want to overpressurize). Highly recommended modification.
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PostPosted: Sun Aug 22, 2021 2:39 pm    Post subject: DIY - Red Teked mine. Some AC info Reply with quote

Using the instructions in this thread I fixed my AC, which now works great! The system was "open" for 5 years. When I replaced the radiator 5 years ago I removed the condenser. I did put tape over the condenser hoses to keep dirt out.

I'm not an AC tech nor have I fixed an AC system before. I am an engineer and do like to fix things. During this I learned a few things which I did not see in this thread. Those are at the bottom, after my AC description.

First, some basic AC theory. I find it helps to know how things work when I'm fixing them. If you are an AC professional be aware I'm cutting out a few details so it is easier for the new folks. Compress a gas and it gets hot. Compressing adds energy. Reduce the pressure and it gets cold. This is the basis of an AC system. If we pretend the AC system was running using air (call it ACair) we'd begin by compressing the ACair in the compressor. The ACair is now hot and has high pressure. This hot ACair goes through the condenser (a radiator) and cools off. Assume the condenser is perfect and cools the ACair to the ambient outside air temperature. After the condenser the ACair is still at high pressure. Only the temperature changed. Next our ACair goes through the expansion valve. This reduces the pressure and the ACair becomes colder. Since the ACair was at the ambient temperature it becomes colder than the outside air. Next, the cold ACair flows through the evaporator (another radiator) making it cold. Air inside the vehicle is blown through the evaporator fins and gets cold. We have cold air in the car! The ACair flows back to the compressor and the cycle repeats. Keep in mind this is a continuous processes and this story follows one little chunk of ACair as it flows through the system.

The AC system could work with air but it would be large and inefficient. There is a better way. Think about a pot of water. It takes 540 times the energy to change a pot boiling water into vapor as it takes to raise the temperature of the liquid water 1 degree C (about 2 degrees F). That is, to change the water from a 100 degree liquid to a 100 degree gas takes 540 times more energy (heat) than it took to raise that same water from 99C to 100C.

In AC systems we use the more efficient boiling liquid idea. To move the energy (heat) from inside of the car we change gas into a liquid, then back to a gas. This is why we have a "evaporator" and a "condenser" and not "radiators".

In the Vanagon AC, the compressor takes a low pressure gas (refrigerant) and turns it into a hot high pressure gas. The condenser (in front) cools the gas enough to turn it into a liquid. That took a lot of energy out of the gas and that energy went into the outside air. The liquid refrigerant flows to the expansion valve, where the pressure falls. What is this expansion valve? Think of it like the a tire valve stem. The tire has high pressure. Push the end of the valve core and air comes out, falling in pressure and getting colder at the same time. The further in you press the valve core the faster the air comes out of the tire. You can regulate the speed which the air comes out of the tire. The expansion valve is a regulated hole. The liquid high pressure refrigerant goes through the expansion valve, the pressure falls, and it becomes cold. The refrigerant is now at too low a pressure to stay a liquid. The refrigerant "boils" in the evaporator. "Boiling" here does not mean "hot". This boiling occurs below the freezing point of water. The evaporator becomes cold and the hot air in your car blows through the evaporator. The refrigerant doesn't need to warm up, it just boils into a cold gas.

You may need to think about this awhile before the "AHA!" moment happens. It's not obvious. Even if the "AHA" doesn't occur, some of this is important when you try to understand why your AC system isn't working.

1) Why can we use R134, R12, or Red-Tek? Lots of materials can work as a refrigerant. It must boil at temperature that works for making an AC system. It may be obvious that water would be a bad choice. R12, R22, R134, ammonia, and others can be used. We also want non-toxic, non-flammable, non-corrosive, and cheap. R12 was the best choice 35 years ago. Thus the Vanagon AC system was designed for R12. R134 is close enough to R12 so it will work. It needs a different oil, but it works.

2) What is the point of the pulling the vacuum? Many reasons. Recall we started with air as an example? It doesn't work in our system designed for R12. If we put in 30 psi of Red-Tek without pulling the vacuum, we added 30psi of Red-Tek to 14.7 psi of air. The air eats up 1/3 of systems capacity. Next, water vapor, which is part of the air, can freeze. It only takes a little to befoul the expansion valve. It is like carb ice. Oxygen from the air is corrosive. Add water vapor for more corrosion. You must get the air and water out.

3) How much vacuum do you need? Someone said 500 microns or less. That is ideal, but you might not get there. What is a micron? There are 760,000 microns at sea level. Not all vacuum pumps can't get to 500 microns. I have two $500 pumps that are rated at 75,000 microns. To get water to boil and leave the system the pressure must be 15,000 microns or less. You need a "high vacuum" pump to get the water out. You really need to have a micron gauge.

I bought the better of the two The Harbor freight vacuum pumps. The pump was $160 or so and claimed 22 microns on the box. My gauge said the pump would pull only 160 microns. That is still good enough. On the Vanagon AC system, I could not get the vacuum below 1,100 microns. I traced this to the hoses that came with my AC gage set. The hoses leak!. Quality matters. Since the idea is to get the water out, and most of the air, I figure 1,500 microns was sufficient. I pulled 1,500 from thin air using "engineer's license". I put the micron gauge on the high port and pulled the vacuum on the low port. Don't put the gauge on the pump! You'll get a bad reading. At very low levels it takes the vacuum a while to work its way through the system.

You can get an AC valve core puller on Amazon for $50. Next time I'd buy 2, one for each port. It makes pulling the vacuum and attaching the gauges much easier.

If you use the refrigerant gauges for the vacuum portion they are not accurate enough. You may have enough leakage that the water doesn't come out.

4) When reading the AC gauges for Refrigerant use Red-Tek's pressure numbers for Red-Tek, The Bentley for R12, and R-134 numbers for R134.

5) Next time, what would I do the same? I disconnected all the hoses, replaced all the o-rings, replaced the expansion valve, replaced the drier, drilled holes in and oiled the AC blower motors, cleaned the mouse nest from the blowers, individually flushed the hoses and components, straightened all the bent fins. When I drained the compressor it had only about 5cc (gasp!!) of dark oil, so I bought a new compressor. I did not replace the hoses.

Important: When I took off the condenser I discovered a substantial amount of bug carcasses in between the fins. Little teeny ones. That will kill the air flow. The bugs were too stuck to wash or soak out. More of my life down the drain dental picking bugs. Had I seen this 5 years ago I would not have bought a new radiator.

I pulled the vacuum down to 1,100 microns. Refilled with Red-Tek.


6) What would I do differently? I'd buy a top quality refrigeration gauge set. The connections liked to come loose and it's hoses leaked vacuum. The German "micron" vacuum gauge and the valve core puller were far superior in quality. I'd buy a new condenser to avoid cleaning the old one with a dental pick.

7) What would I ignore? I didn't test the output temperature at completion and still wouldn't. My wife wanted the AC fixed. On the test drive she put on a jacket and said "If it gets any colder in here....."

Cool Components. I saw mention of "better large capacity parallel flow condenser" and questions about higher output compressors. AC is a system. In theory the evaporator, compressor, condenser, and so on are all sized together. All condensed is the best it gets, the same with evaporating. If you make the compressor larger it will cycle on and off more often. That won't increase the cooling but it should decrease the efficiency and compressor life. If I had to replace the condenser I would get a parallel flow one but would not expect an increase in performance. That is just an opinion. I did take "Heating Ventilation and Air Conditioning" as an engineering elective. However, that was 35 years ago.


I want to thank the posters on this thread. I did not think it was worth attempting to fix the AC. Not only does it work, it works extremely well!


P.S. This is a 1987 Vanagon Syncro tin top with factory air. It is all stock. It is from New Mexico and has never seen road salt. A lot of the parts still have the yellow cad coating. Condition was a factor in keeping the hoses.
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PostPosted: Sun Aug 22, 2021 3:25 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

What an excellent and comprehensive presentation of the essentials. Thanks!
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PostPosted: Wed Sep 15, 2021 1:37 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Calling all RedTek Vanagon AC experts...

I recently replaced all the AC system components in my 90 Vanagon SVX except for the evaporator and compressor, including all new lines. The system was previously working well with R12, but had a leak so I decided to take the plunge and convert to RedTek. The evaporator was thoroughly cleaned and dried during the conversion, and the system was vacuumed down to -29 for half a day before charging with RedTek.

After charging the system to capacity (3 cans of RedTek), low/high pressures were:
- Static = 80/80
- Idle = 50/180
- 1500 rpm = 45/195

With an outside temp of 85F, the vent temps were 65F. I concluded that this weak performance (low pressure was too high) was likely a bad compressor, so drained the system and pulled the compressor, and stripped it down. It was pretty corroded inside, so presumed this was likely the culprit.

I had a second original Subaru SVX compressor which was good and clean inside, so I rebuilt it with all new seals. After installing the rebuilt compressor, adding the same amount of mineral oil to the new compressor that came out of the old compressor, replacing the receiver/drier, vacuuming the system and recharging again, performance is much worse, with barely any difference between low and high pressures.

The compressor turns smoothly, and is correctly engaging the clutch.

Before I go and buy a new compressor (and go back to Compressor Rebuild School...bah!), are there other things I may have missed? Bad expansion valve? Expansion valve installed backwards? Note that I installed the RedTek with the cans inverted (i.e. as a liquid).

Thanks all.
Matt
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PostPosted: Wed Sep 15, 2021 2:17 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

1+1= 2

You had a working system but wanted better

You got a used compressor and rebuilt it

You installed it and now you have no function.

Providing you changed nothing else, you have a bad compressor.

And by the way, those numbers aren’t half bad.
You are right in range. You only needed to play with quantity in the system while checking temperatures.

Also air movement through the Condensor affects pressures,

Dave
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PostPosted: Wed Sep 15, 2021 3:42 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

mattmoox wrote:
Calling all RedTek Vanagon AC experts...

I recently replaced all the AC system components in my 90 Vanagon SVX except for the evaporator and compressor, including all new lines. The system was previously working well with R12, but had a leak so I decided to take the plunge and convert to RedTek. The evaporator was thoroughly cleaned and dried during the conversion, and the system was vacuumed down to -29 for half a day before charging with RedTek.

After charging the system to capacity (3 cans of RedTek), low/high pressures were:
- Static = 80/80
- Idle = 50/180
- 1500 rpm = 45/195

With an outside temp of 85F, the vent temps were 65F. I concluded that this weak performance (low pressure was too high) was likely a bad compressor, so drained the system and pulled the compressor, and stripped it down. It was pretty corroded inside, so presumed this was likely the culprit.

I had a second original Subaru SVX compressor which was good and clean inside, so I rebuilt it with all new seals. After installing the rebuilt compressor, adding the same amount of mineral oil to the new compressor that came out of the old compressor, replacing the receiver/drier, vacuuming the system and recharging again, performance is much worse, with barely any difference between low and high pressures.

The compressor turns smoothly, and is correctly engaging the clutch.

Before I go and buy a new compressor (and go back to Compressor Rebuild School...bah!), are there other things I may have missed? Bad expansion valve? Expansion valve installed backwards? Note that I installed the RedTek with the cans inverted (i.e. as a liquid).

Thanks all.
Matt


I see several problems:

1. The oil charge for the Vanagon system, for PAG oil (you used mineral oil which should be the same quantity, but I can't say with certainty) is 8 fluid ounces. Without adequate oil, the teflon rings in the compressor won't seal well;

2. You install the refrigerant as a liquid ONLY IF THE COMPRESSOR IS NOT RUNNING. If you fill liquid refrigerant directly into the compressor, you will get hydrostatic lock in the compressor with typical damage that flows from that approach. Granted, by the time the RedTek flowed through your gauge set, it likely flashed to vapour, but who knows?

3. The SVX compressors I have seen (1993 to 1997) all used R134A and therefore used PAG oil. The residual PAG oil in your compressor may have mixed with the VW factory fill of mineral oil to turn into a gummy mess;

4. You may well have a malfunctioning TXV, especially if the oil mixture gummed it up.

5. Remember that the SVX compressor is a variable-displacement compressor. Although it would be unusual, an older compressor may be "stuck" in the low-displacement position. Alternatively, you may have connected a power source to the actuator thinking that one was required.
Not so. Note that if no electrical current is applied to the variable-displacement actuator, then the compressor is supposed to operate at maximum displacement.

See my pic below: Only the one connector should be wired unless you are using the Subaru factory AC control head to operate your AC, which I doubt. There are two connectors, a wide one and a narrow one. The wide one is for the variable displacement actuator and it should have no wire connected to it in a Vanagon conversion. The narrow connector is for the compressor clutch solenoid and must be connected.

Image may have been reduced in size. Click image to view fullscreen.


Regardless of the high side pressures, you want to see 29 to 33 psi on the low side when the engine is at high idle (say, 2,000 to 2,500 rpm), with good air flow over the condenser, to hit the minimum vent temps. With three cans of RedTek, I would not expect that your system is seriously overfilled, but it may be worthwhile to vent some RedTek to get low side pressures down as a diagnostic. If the TXV is the problem (or the other potential causes I mentioned above), you will be opening the system anyway, so you might as well vent some RedTek as a diagnostic test to see if you can get decent vent temps. If the compressor is weak, due to age, damage or your rebuild, then it will struggle to achieve the low-side pressures without lowering the refrigerant fill level to an unsafe level. Remember that the ability of the refrigerant oil to move through the system to do its job of lubricating the compressor, there ahs to be enough refrigerant in the system to carry the oil mist. The reduction in oil movement is not linear in relation to refrigerant fill level - - it is more like a cliff. At a certain low refrigerant fill, oil movement is minimal and compressor damage will occur. This is why, even though you may improve vent temps by venting some refrigerant, it is not a good solution.
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mattmoox
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PostPosted: Thu Sep 16, 2021 7:16 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Thanks Howesight.

Mine is a 1992 EG33, and they ran R12 with mineral oil to the best of my knowledge. Both the compressors I have are from 92's. The variable-displacement solenoid is not connected; only the trigger wire to the compressor.

Today, I pulled out the expansion valve, and stripped it down - clean as a whistle. It was replaced when I did the full rebuild. I also stripped down the compressor again, as I had a lingering doubt that I never drenched the teflon piston rings in mineral oil before I put it back together. I took all the rings out and made sure they were all soaked in oil this time...

After putting it back together, it held a solid vacuum down to 30. I only had around 3/4 of a can of Red Tek left, so I sucked it in as a liquid under vacuum. The static pressure was around 35, and when the compressor kicks in, the low pressure reading was pulling down to around 25

I'm waiting for more Red Tek in the mail to see how the story ends, and whether I need to buy a new compressor...

Hope the smoke is treating you right up there in BC.

Cheers for the help
Matt
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Howesight
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PostPosted: Fri Sep 17, 2021 4:13 pm    Post subject: Re: DIY - Red Tek conversion Reply with quote

Glad to help, Matt. Let us all know how this intriguing problem works out when you get it sorted.
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