DIY - Red Tek conversion

jimf909 · Posted: Sun Jun 07, 2015 8:48 pm Post subject:

Every once in awhile I get a notion to get the a/c working in my van (and I will, someday, after the Bostig is started and complete and after...) so I start reading up on it, my head spins and I'm thankful I live in Seattle where it's needed so rarely. That's what I've got. Completely useless here. Sorry about that.
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- Jim

Howesight · Posted: Mon Jun 08, 2015 12:26 am Post subject:

AndyBees

I wish I'd discovered Red Tek sooner (during 2011-2012) back when I was doing the TDI install in my '84 tin-top. However, my R134a conversion has turned out pretty good thus far.

I modified the AC compressor that come on the TDI engine as well as retrofitted the fittings to fit the old Vanagon hoses. The AC Compressor modification can be seen in Post #520 in this link: http://forums.tdiclub.com/showthread.php?t=276798&page=35 Also, here is a link with more info about the RCV valve ... and AC in general: http://www.aircondition.com/sitesearch.htm?cx=part...3134356j37 (scroll down and read the PDF file on Decreased Cooling in GM and VW cars.....)

In this link, at Post #378, you can see how I adapted the OE TDI AC Compressor to the Vanagon AC hoses: http://forums.tdiclub.com/showthread.php?t=276798&page=26

I removed the Evaporator as part of the plastic housing repair. I cleaned the evaporator of 30 years accumulated dust and lint... Also, replaced the expansion valve with one that "supposed" to work with R134a.

Anyway, things I did and didn't do:

1. Installed a new Dryer
2. Did not replace any O-rings except those at the compressor
3. Did not flush the lines or condenser
4. Did flush the evaporator but not with the professional stuff
5. Did do a long vacuum and let sit overnight
6. Did add stop leak
7. Did add oil
8. Did inspect the hoses for nicks, rubbed spots, etc., and cleaned them with silicone lube .......... (probably of no benefit).

In charging, the system seemed to work fairly well with two 12 oz cans of 134a. With ambient temp at about 80f, the high side achieved about 200 psi with the low side hanging around 30 psi..

Well, just sharing my story! Thus far, it seems to work okay! If it gives problems, I'll probably be going with a Red Tek conversion...
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

porterbrown · Posted: Sun Jul 12, 2015 4:33 pm Post subject:

Without going through all 44 pages, can somebody remind me what should be seen through the sight glass on the receiver/drier if the system is full?

I.e. I'm seeing a milky white liquid and suspect my system needs a recharge. With other refrigerants, milky white is a good sign of low refrigerant. Same with red-tek?

Thx!
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'90 Westfalia GL Automatic

djkeev · Posted: Sun Jul 12, 2015 5:27 pm Post subject:

RedTek R12a, behaves very much like R12.

You will see streams of bubbles on a low charge condition or with a too much moisture in the system condition.

Dave
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Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

Refrigerant is refrigerant at the sight glass--

It doesn't make any difference what your using, if you seeing anything else but clear, correct as needed / required.

If you're seeing milky or cloudy at the sight glass this points to the dessicant in the dryer has broken down and is circulating it through the system.
If you're diagnosing what you're seeing correctly.

If you're seeing foamy in the glass you have a low charge & probably air has entered the system.

Either way, you have some issues to correct to get the AC working up to snuff.
_________________
T.K.

AndyBees · Posted: Fri Jul 17, 2015 3:01 am Post subject:

That's not true with R134a refrigerant.

R134a is not the same and will not act the same by any means as R12 or any of the other substitutes in a retrofit such as the Vanagon AC system. The oil used with R134a does not mix with the gas or liquid and will flow in globs. And, "bubbles" will be observed in the sight glass of a perfectly operating R134a retrofit system.

Bubbles in the sight glass is vapor refrigerant. R134a is suppose to be installed based on weight and observation of the manifold gauges must be taken into consideration with respect to the ambient temp during installation.

I doubt you could put enough 134a in the Vanagon system to show liquid at the glass without blowing a hose or seal. A little over two cans of R134a in the Vanagon system will provide acceptable cooling. And, during operation there will be a continuous flow of bubbles (and oil globs).

As I understand, Red Tek does act very similar to R12, thus, if the system is properly evacuated and charged, little to no bubbles will be observed at the sight glass.

Notice in the link below that observation of the sight glass is not recommended. Read the entire article (guide) for some interesting info. No, it does not cover Red Tek.

http://www.aircondition.com/tech/questions/95/Basic-Charging-Procedures

When converting my Vanagon to R134a I was advised by a professional auto AC tech to disregard the sight glass altogether. And, technically, R134a is supposed to be installed by weight using an appropriate scale... obviously we all don't have or have access to such sophisticated tools.
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

If you have moisture, air, or a low charge, broken desiccant in the system the sight glass will most certainly tell you so--
Refrigerant is refrigerant, doesn't make any difference if it's R-22, R-12, R-12A, 134A, R-409.
You see air bubbles or foaming in the sight glass, and low or no cool, odd pressures, you've got charging issue's.

In this article I will be focusing on the steps involved in diagnosing, repairing and recharging your air conditioning system on the 1984-92 BMW E30 3 Series. Keep in mind that this technical article is written with my own BMW 325is in mind, however the procedures and information herein can be applied to nearly every modern car with air conditioning out there on the road today.

First off, lets begin by first explaining in layman's terms how air conditioning works.

Compressor

The main function of the compressor is to compress and pressurize the refrigerant in the system, and also to keep the refrigerant moving through the system when the A/C is turned on. The compressor is belt driven off the engine. The compressor takes in cold, low-pressure gaseous refrigerant and compresses it. As it compresses, it builds up heat. This now-pressurized hot gas is sent to the condenser.

Condenser

The condenser then receives the hot gaseous refrigerant from the compressor. Usually, condensers are placed in the front of a car, where it receives oncoming airflow from the radiator fan. The condenser then turns the hot gas into a liquid. This liquid (still under high pressure) is then sent to the receiver drier.

Receiver Drier

The receiver drier next receives the hot pressurized liquid refrigerant from the condenser. It is essentially nothing more than a desiccant tank. It removes moisture from inside the hot liquid refrigerant. Moisture in the lines is a potential problem, as refrigerant can eventually react with moisture and corrode the insides of the system. The process is completed when the hot liquid refrigerant then exits the receiver drier and passes through the expansion valve.

Expansion Valve

The expansion valve receives the hot liquid refrigerant. It allows the pressure of the liquid refrigerant to drop. The drop in pressure causes the liquid refrigerant to cool down. The result is cold liquid refrigerant, which is then sent to the evaporator.

Evaporator

The evaporator receives the cold liquid from the expansion valve. The evaporator is usually located inside the car under the dashboard.When you turn on the A/C fan, it channels air over the evaporator, cooling the air; this air is then blown through the vents of the car. As the cold liquid passes through, it evaporates from a liquid back into a gas, and is then routed back to the compressor to start the entire process again.

Additionally, there are two more components to the system that control the operation when you turn the compressor on and off.

A/C Clutch

The A/C Clutch is used to engage or disengage the compressor when you press the A/C button on the dashboard. When the A/C is turned off, the belt that drives the compressor spins freely on the A/C Clutch, which is mounted on the front of the compressor. Now when you push the A/C button, it sends current to the clutch, which locks it and allows the compressor to begin turning. High Pressure/Low Pressure Switch

These two switches are a built-in safety feature. When the system pressure is too low it interrupts the voltage going to the clutch on the compressor, which then disengages the drive belt from the compressor, and turns off the A/C. It works the same way when it senses there is too much pressure in the system.

So now that I have explained a little about how the system works, we can now begin to go over the steps involved with recharging your A/C system. The first thing to know is that there are two types of refrigerant used in most modern A/C systems, R-12 and R-134a.

Up until about 1991, all major automobile manufacturers used R-12 as a refrigerant in A/C systems. It was discovered that R-12 contains CFC, or chlorofluorocarbons, which destroy the ozone layer. Hence it was necessary that they come up with a replacement. This came in the form of R-134a. Nowadays every car uses R-134a. There has been much debate over the years as to how well R-134a works as an automobile refrigerant. When R-134a was first used in cars, it was not uncommon to notice that the new refrigerant simply did not cool as well as the older R-12. It was also pretty common for the A/C system to emit unpleasant odors after running for long periods of time. These days engineers have sorted out nearly all of the problems first encountered.

These two types of refrigerants cannot be used together. For instance, you cannot put R-134a directly into a system that originally used R-12. Thus we run into one of the major problems with recharging A/C systems. R-12 is no longer available to the general public. I have heard of certain vendors that do still make R-12, however it is unlikely that one could purchase it. These days, A technician has to have a special license to purchase and charge R-12 systems. What this means is that you can still have your old R-12 system charged, however the increasing costs of stockpiled R-12 is making this less and less of an option. If you choose to have you're A/C recharged at a shop that still services R-12 systems, expect to pay $50 a pound or more. As most cars use two pounds or more of refrigerant, you can quickly see why R-134a becomes a more attractive option. I also have heard of products on the market that are a direct replacement for R-12, such as Freeze 12 or Duracool, however I have no direct experience with using them. I have heard from various sources that Freeze 12 seems to work very well as a direct replacement.

You may be asking now what is involved in converting to 134a. Well, there are many "kits" on the market you can buy at your local auto parts store that say all you have to do is replace the fittings on the fill ports, and recharge using R-134a. I wish it were this easy. The simple fact is that a lot of preparation work needs to be done in order for the A/C to work correctly with the new refrigerant. To correctly convert to 134a, you need to replace all the seals in the A/C system. The original seals in the system were designed to work with R-12. The chemical composition of the R-134a will eventually degrade the seals, causing the refrigerant to leak out. You will also need to purchase a receiver drier specifically for R-134a. The last step is to also convert to a R-134a compatible compressor. I have heard that it is possible to use an R-12 compressor to do this, however it will require a total flush out of the compressor, as well as replacing all internal seals with R-134a compatible seals. When you get into this realm, it is easier to simply replace the compressor. I have also heard that depending on the climate, you may also need to replace the condenser to a unit with a larger surface area. If you were to take this to the shop to have it done, the cost and labor involved in doing this can easily exceed $1000 or more.

Now look at the top of the sight glass on the receiver drier. A steady stream of bubbles usually indicates that the system charge is low and needs to be topped up. Streaks on the inside of the glass usually indicate that there is no refrigerant left in the system. Once you have finished checking the sight glass, shut off the engine.
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T.K.

AndyBees · Posted: Fri Jul 17, 2015 1:05 pm Post subject:

Very well versed on the topic.... thanks for clarifying the water..

Charge up a Vanagon system with R134a until you cannot see bubbles in the glass window on the receiver/dryer and it will blow a seal, hose, destroy the compressor, burn the clutch or something else will give up the ghost. Not so with R12, Red Tek, propane, etc., but obviously there is a limit, thus the need to use a set of manifold gauges.

And, yes as the pre-1991 auto's AC systems went south, shops made a fortune changing them over to R134a until the laymen learned that not all of those things were necessary to have a very functional retrofitted system. Example, I've changed-over numerous VW Rabbits/Jettas/Dashers/Quantums without replacing O-rings, compressors, etc., of course I did replace the Receiver/Dryer. In many cases, I did replace clogged expansion valves..... and, sure, replaced those disturbed O-rings.

It's not rocket science!
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

I'm not saying that a guy can depend only on the sight glass to service his ac system.

Loading up refrigerant without gauges would be foolish.

However, if anyone had a high / low pressure problem, and had the gumption to find out why, a simple peek at the sight glass would offer a quick explanation of what's going on.

Simple, quick, and pretty accurate tool that most folks don't know It's already in position to do that job---free.
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T.K.

RBEmerson · Posted: Sat Jul 18, 2015 3:15 pm Post subject:

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

Considering how long the lines are in a Vanagon, where the major components are located, unless you own some sort of bodacious vacuum $800.00 big CFM evac pump , your looking at a several hour draw --minimum---

Overnight is plenty to detetmine if you have a tight system.
_________________
T.K.

AndyBees · Posted: Sun Jul 19, 2015 1:48 pm Post subject:

When I changed my Vanagon over to the R134a, I installed a new dryer/receiver and expansion valve, both rated for the 134. I only changed O-rings at those two devices. I inspected the hoses and all other connections for signs of a leak.

I pulled a 29 inch vacuum and let it sit overnight. It held (inside an air conditioned garage at the same temp). I have a commercial AC evacuation unit.

If I remember correctly, the Vanagon (non-Westy) system holds 56 ounces of R12. At two 12 ounce cans of R134a, the high side was at 200 psi with ambient in the 80s. The low side was in the high 20s. It seemed to be cooling just fine but there were bubbles going through the sight glass. I was told by several individuals that the Vanagon system would only need about half as much R134a refrigerant and not to worry about the bubbles.

So, we used the Van in the summer of 12, 13 and 14 with good cooling. However, I did have to add about a half can of refrigerant at the beginning the 2014 cooling season due to a leak at the compressor.

The right side motor mount bracket goes under the AC pipes at the AC Compressor. In the fall of 2013, a mount bolt broke which let the Compressor pipes sit down on the mount bracket ... holding a considerable amount of weight. I upgraded the motor mount brackets but left the AC pipes alone.

Anyway, that incident caused the seal and/or weld (modified to fit TDI AC Compressor) to leak refrigerant. I had to add a full can of refrigerant for the 2014 cooling season (worked fine all summer).

Well, back in late April of this year, I needed the AC ... no cool! I checked pressures with the manifold gauges. The system was very low. So, rather than just add more refrigerant, I decided to do an evacuation and added AC Stop Leak with oil & red dye and two cans of R134a ....... big mistake!

The first week or so, it cooled just fine. Then the AC coil fried ... then another one. I installed a new coil and clutch ....... checked pressures... near 200 psi on the high side with the low side near 10 psi .. Wow.

So, I found the Expansion Valve to be plugged. Installed a new one and began another charge... still high side and low side out of balance bad. Then, I noticed the exit pipe from the Dryer was cold and sweating.. So, it's obvious the dryer is plugged.

Now, I am at a cross roads...

- Clean system (and the debate goes on and on as what to use and how)
- New expansion valve
- New Dryer
........................................

Do I go with Red Tek or stay with R134a?

And, is anyone familiar with the new EPA regulations that are about to hit the AC industry?

http://www.epa.gov/ozone/snap/
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

shadetreetim · Posted: Sun Jul 19, 2015 3:01 pm Post subject:

I have been struggling with my AC lately as well. As my story goes; Over the previous few years I had flushed the system, replaced the dryer, expansion valve, and compressor, eventually replaced all rubber hoses and seals, ran Redtek successfully, nice and cold. Easy! Why does anyone think this stuff is hard, right? Laughing

Last summer I swapped in a 1.8t, and modified the hoses to fit the compressor on the new motor. At the time I only had 2 cans of Redtek and 1 can of stop leak to charge the system with, so I dumped it in. Air was cold but not great. I ran it that way the rest of the summer. This year we really hadn't needed the AC until recently. I decided to order some more Redtek and top the system off.

Embarassed

Unfortunately, I didn't think about it and added Redtek to the low side with the compressor running and the bottle inverted. Yeah. Not so good. My high side pressure isn't high anymore. I am assuming I blew out the compressor. As I attach and remove my gauges, the Redtek coming out is dark grey and seems like it has grit in it? Is that grit the stop leak? Or parts of the compressor?

I am thinking my next steps are to order a new compressor and a new dryer, flush the system, vacuum, and then stick in some fresh Redtek.
_________________
Tim Potts

Doing my best every time I drive it to dispel the myth these Vanagons have to be slow!

'89 Vanagon Bluestar/Country Homes 1.8T & .77 4th
'74 Jeep CJ5

AndyBees · Posted: Sun Jul 19, 2015 3:22 pm Post subject:

shadetreetim · Posted: Sun Jul 19, 2015 3:39 pm Post subject:

Terry Kay · Banned Joined: June 22, 2003 Posts: 13331

Tim,
You are 100% correct.
Compressor running gas only, can upright.

Giving the system a blast of fluid is not condusive to the compressor vanes.
Not good at all.

I've never had any issues with the pro seal from red-tek.
It seeks out the loss of gas from a moisture leak & seals that area only.
It isn't gritty.
I think that your dealing with vane particles.
_________________
T.K.

AndyBees · Posted: Sun Jul 19, 2015 4:01 pm Post subject:

Ah, I didn't catch the inverted...

I do invert the can but only for a couple of seconds. It will vaporize by the time it reaches the Compressor if you are using a regular set of manifold gauges. I suspect the short applicators would be a problem.

Well, I don't think switching to Red Tek is a hard thing to do. It's just a matter of making the decision to do so and then doing it!

Is there a web site that sells it by the can, case, partial case, etc., without throwing in a "retro-fit" kit with stop leak (not for free)?

As I do searches, seems everything goes to eBay where most offers are kits or high priced individual cans?
_________________
'84 Vanagon Tin-top, ALH TDI. 1989 Tin-top
1983 Air-cool, 225k miles, 180k miles mine. Seven trips to Alaska from 1986 thru 2003.

shadetreetim · Posted: Sun Jul 19, 2015 4:20 pm Post subject:

porterbrown · Posted: Sun Jul 19, 2015 4:20 pm Post subject:

Can someone please clarify why the direction has been given to NOT invert the can? The Red-Tek website specifically says to invert the can...

5) Invert the can. (Turn upside down). Make sure can is inverted through entire charging process.

http://redtek.com/English/product.asp?ID=50

I'm not necessarily disagreeing, and I'm sure there's good reason but just wanting to better understand why we should not follow the manufacturers instructions.

Thx!
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'90 Westfalia GL Automatic


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