DIY - Red Tek conversion

[Abscate]

You can use compressed air to leak test, you just have to pump down for. A few hours to bring moisture levels down. Most of us don’t have access to N2 at 160psi

If your compressor only hits 100 psi use that
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.ssS!

[djkeev]

Watching this ^^^ with interest.

We have another member here running a Subaru who is struggling to get a good temperature drop.

He has done everything outlined in the rebuild threads.

New hoses
New condensor
New Rec/Drier
PAG oil
RedTek
A new genuine VW H style expansion Valve (a twin to the one I installed)
Flushed Evaporator, etc,

He was using and older Subaru compressor but a month ago put on a brand compressor ..... bug bucks!

In short everything that I have done to both my 86 and 90 except for the compressor brand. I have passengers wrapped up in sweatshirts and blankets!
He is rolling his windows down to move some 90° humid air!

We wondered about compressor capacity, we determined that the Subaru compressor pretty much matches the Sanden 507 (early 86 and earlier) on pumping capacity.

He has very high high pressure numbers with a decent low pressure number.
Nothing he has tried remedies this and gives good cooling.

I've questioned if the condensor is properly install, it seems to not be dropping the heat.

Talk about frustration!

Other Subaru conversions are putting out freezing air.... not his.
There is an answer eluding us on this one.

Dave
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Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[JudoJeff]

H valve not working or a plug somewhere in the system.

If H valve was even partially working he would have some cooling.
Everything else is new and I assume connected correctly. Many of those valves are defective now right out of the box. Older ones are better.
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1989 Vanagon GL Westfalia Camper, Burned up on 7/31/16.
1987 Vanagon GL Westfalia Camper, Bostig & Rebuilt, sold
1986 Vanagon GL Westfalia Camper, Bostig Sold May 10, 2021
1999 Ford GTRV Westfalia camper (30% bigger Westy layout)

[djkeev]

[mattmoox]

Thanks for the suggestion on aftermarket H valve. When I originally replaced all my AC system, I took the advice in the original thread and replaced the H valve too. I have a horrible feeling that I threw out the old one (which was working well with R12....grrr), but will have a rummage today and see if I still have it.

Anyone got a recommendation on where to buy a working H valve?

Here's the one I have at the moment:

https://www.partsgeek.com/review-product/0Y15Z1R942L/7340-01369372/

And some questions on H valves -

Is there a way to test the H valve out of the van to confirm it works? As I mentioned before, I did already strip down my current H valve - removed the brass plug and checked that the spring valve moves freely. All good.

Is there a way to test that the H valve diaphragm moves as expected?

Is there a method to calibrate the pressure on the H valve spring (i.e. the how far the brass plug is screwed in)?

Kind of annoying that a $30 part is (perhaps?) the one thing that let's down a $1000 overhaul!

I am encouraged however by all these reports of needing to buy a sweatshirt when this thing is done

Cheers all.

[JudoJeff]

Hi,
I answered this off top of my head. After Dave’s nice reply, I researched it. Assuming everything is connected properly, and working the experts said:

1. Overcharge of refrigerant or oil
2. Blockage in the system

My A/C notes went to the buyer of my Westfalia, sorry I can’t be of more help.
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1989 Vanagon GL Westfalia Camper, Burned up on 7/31/16.
1987 Vanagon GL Westfalia Camper, Bostig & Rebuilt, sold
1986 Vanagon GL Westfalia Camper, Bostig Sold May 10, 2021
1999 Ford GTRV Westfalia camper (30% bigger Westy layout)

[djkeev]

I know of no way to test the H style expansion valve.

I do know that the older L style with the temp probe can be adjusted but haven’t ever done so.

The gentleman I purchased my 86 Westy from was horrified when I told him I replaced the expansion valve.
He was an old HVAC technician and had put many hours into adjusting that old style L valve to produce maximum cooling.
After my after market one didn’t work I reinstalled his adjusted one with excellent results.
It is still working today on the West Coast.

Like Jeff says, I too have stumbled upon the concept of too much PAG being a reason for poor cooling performance.
The thought of disassembling and cleaning out the entire system to KNOW your PAG level is daunting!
And to do this without knowing if is the problem or not?
It could be an action of futility.
This particular Subaru powered system has already been confirmed to NOT have any blockages in the system.

Honestly we are down to pulling our Hair out!

The high high pressure indicates the gas is not dropping its heat in the Condensor or an expansion valve issue. I feel the expansion valve has been ruled out by installing the NOS VW Valve in the VW box.
Why then isn’t the gas dropping the heat?
Undersized Condensor ?
Poor gas flow in the system as a whole, in the Condensor specifically?
Poor air flow through the Condensor?
Incorrect gas flow direction in the Condensor?
Too much PAG gumming up the gas flow or effectiveness of the gas?

You don’t want to just randomly drop some PAG out of the system not knowing if the quantity left is adequate for safe operation.

The selection of poor performance possibilities is growing increasingly smaller with each try at a repair.

I’ve even brainstormed multiple times on the phone (most recently yesterday afternoon) about this problem vehicle with one very well versed in Vanagon A/C operation and RedTek in particular.
He too is now stumped.

I’m thinking a good Winter project for the owner will be to drop the evaporator, disconnect hoses and components and flush them all out.
Refill with a known proper quantity of PAG in each component and try it.
An overfill is quite possible on this rig for over time suspected components have been replaced and new bits have been installed with the suggested by VW Vanagon Oil capacities.
There is absolutely no way to know how much oil is in the system, even after flushing it clean, it will be an unknown quantity that comes out with the flushing agent.

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[Farf]

[dan macmillan]

What are your pressures at. What is your superheat value.
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Licensed Automotive Service Technician
Licensed Truck and Coach Technician
Licensed Heavy Duty Equipment Technician
CFC/HCFC/HFC A/C handling and installation license
Alignment specialist
66 Modified Manx,68 Kyote,74 Thing,74 Beetle, 76 Transporter,75 self made Double Cab,65 Meyers Manx,78Westy,68 Ghia, 79 Bradley GT2
Current projects:
Built for others:69 Manx Clone

[Farf]

Superheat? Subcooling? Sanden system service chart below with a link to an inexpensive thermocouple thermometer. This has been mentioned in the past, no takers yet. Note, I added the evaporator outlet temp. line.

https://www.amazon.com/Stainless-Thermocouple-Ther...mp;sr=8-24

[djkeev]

[djkeev]

Is there a way to test an H valve?
I said not that I know of ….. but I recently learned that a can of electronics dust remover, aka canned compressed air, uses a refrigerant propellant to push the air out.
Hold the can upside down and spray, the propellant comes out.

Spray the sensor head of the H valve with the fan upside down, while operating pressures should drop about 50 lbs. Sadly, In our rigs, much disassembly is required to do this while running.

You might see meter pin movement if the H valve is out of the vehicle but it isn’t much.

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[Abscate]

I’ve never used HC based refrigerants like Redtek but my understanding is the high side head is about 1-2 that if R134A

If the Subaru guy has high head pressure relative to R134A numbers, he is either massively clogged or has residual R134A , or both
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.ssS!

[djkeev]

[Abscate]

High pressure redtek about 1/2 of R134A , correct
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.ssS!

[pdm777]

I say, start with a clean slate.

We have No Idea what the prior owners have put
into the AC system. Stop Leak/Dye/Oil etc.

Most 'refill' kits have stop leak, yellow dye, and Oil.
You will end up with compromised cooling when there
is an excess amount of these additives.

I flushed at the dryer fitting (always replace the dryer) with a funnel
to get 2-3 cups of Menthanol into the lines, and then blow it through the lines with compressed air and out to a bucket. Rinse and Repeat.

Filthy, Ugly Snot will come out of the lines !!!
Keep flushing until the solvent is clear, then blow out
the lines with compressed air for 30-60 minutes.
Your AC System is now as Clean as New.

Take the compressor off and fill with solvent,
rotate the moving parts and get all of the Old Oil out.

Refill with New oil, New refrigerant.
I prefer Red Tek or EnviroSafe, they have much less high side pressure
and mimic the original R12 without the environmental concerns.
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1990 Westy Full Camper