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floodwood
Samba Member
Joined: October 22, 2017
Posts: 163
Location: Cambridge, MA
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 Posted: Tue Jun 21, 2022 2:39 pm Post subject: 1991 Tintop Air Conditioning Rehab Attempt |
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I am attempting to rehab my air conditioning system in my 1991 tintop. When I purchased the van in 2019, the air conditioning ran marginally well, but over the past few years has degraded to the point where the system is mainly used for the blower fans to move air - and even this appears to be a risky proposition due to the risk of relays overheating and causing fires in the rear.
As such, with the help of a few members and the numerous helpful threads on this site, I have done some preliminary investigation into the system. I have summarized some findings below and am requesting advice as to where to head next.
1. Compressor clutch is not engaging. Clutch is known to be good (jumped with 12V power) - this is apparently a result of extemely low pressure in the system
2. Per receipts from the PO of the van, the system appears to have been filled with R134a refrigerant a few times over the years. However, upon closer look, my high (D pillar?) and low pressure (off compressor?) ports appear to be R12 fittings. Pics are below
3. Switches and Power - the double a/c relay (171-959-41A) appears to work properly when jumped, but occasionally on fan speed 4 it will "chatter" (open and close repeatedly)
4. Switches and Power - System only seems to work if the snowflake switch (E35? Thermostat?) is turned all of the way on.
Questions:
1. Per the phds on this site, apparently the soft hoses of R12 are too porous for R134a refrigerant, allowing the R234a refrigerant molecules to seep out through the hoses.
Is it possible that I have a functioning system, but the r134a is simply leaking out over time, then being recharged? If so, what hoses need to be replaced in totality on the van
2. What parts are worth replacing? Based on my minimal A/C knowledge, I have an old series flow condenser up front, an evaporator in the rear cabinet, a receiver drier (what does this do) hiding somewhere, and a rats nest of wiring in the D pillar
3. What wiring improvements need to be done to safely use the 3 and 4 fan speeds to at least obtain the airflow provided by the fans?
4. Am I missing anything else
5. Should I take the van to an A/C shop to have the system converted to R134a and filled? I do not have the tools to check for vacuum or for leaks, which a shop could do.
R12 Port
My references
(please note that I have replaced the 50A fuse with a new one below)
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Red Ryder
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Joined: June 26, 2021
Posts: 951
Location: Northern California
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| Posted: Tue Jun 21, 2022 3:40 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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As you have observed, the photos with a black cover on the high pressure port at the D pillar indicates the AC has not been converted from R12 to R134a. The low pressure Schrader-style port at the compressor also shows no sign of conversion. In the photo showing the various parts numbered, you will see a larger red port cover. This system has been converted to R134a.
Personally, I would take it to a qualified auto AC shop for evaluation and an estimate for repair. A simple leak test and refill with R134a refrigerant should run about $150. Conversion plus any needed replacement parts will be much more.
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“Scarlett” — 1990 Vanagon Carat Wolfsburg Edition
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djkeev
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Joined: September 30, 2007
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Location: Reading Pennsylvania
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Ahwahnee
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Joined: June 05, 2010
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Location: Mt Lemmon, AZ
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| Posted: Tue Jun 21, 2022 4:37 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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FWIW - I still use R12. These days I suspect a system fill doesn't cost much more than a tank of gas.
I don't think anything works as well as R12 and used in a system that is leak-free and properly maintained it will be fine for a very long time. Mine still works great in Tucson heat, last service was more than a decade ago. |
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bajabones
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Joined: April 17, 2019
Posts: 133
Location: Tacoma, WA
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| Posted: Tue Jun 21, 2022 4:45 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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I am a commercial A/C guy not auto A/C
I have never heard of R12 hoses not rated for R134
If it had R134 already then it’s been converted
The R12 fittings has nothing to do with it
Any A/C guy can put R134 through R12 fittings
Have it pressure tested
Then new receiver drier, it’s filters with desiccant
Then recharge with R134
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floodwood
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Joined: October 22, 2017
Posts: 163
Location: Cambridge, MA
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| Posted: Tue Jun 21, 2022 4:53 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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| djkeev wrote: |
Is this the unit Stephen called me about the other day?
Dave |
Yes |
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djkeev
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Joined: September 30, 2007
Posts: 32561
Location: Reading Pennsylvania
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| Posted: Tue Jun 21, 2022 6:09 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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| bajabones wrote: |
I am a commercial A/C guy not auto A/C
I have never heard of R12 hoses not rated for R134
If it had R134 already then it’s been converted
The R12 fittings has nothing to do with it
Any A/C guy can put R134 through R12 fittings
Have it pressure tested
Then new receiver drier, it’s filters with desiccant
Then recharge with R134 |
Well.........
IF r134a runs just fine in the old R12 hoses......
The Barrier style A/C hoses would not exist! There would be no need for such a product.
Some say the old r12 and mineral oil has sealed all of the porous properties of the r12 hose and r134a will not pass through this "conditioned" hose.
Hmmmmm I don't buy this theory. Is it like new wine in old wine skins?
The auto A/C industry recognizes this r134a permeation problem as well.
Many lose their r134a in systems with no detectable leaks.
Many report interior r12 hose degradation with the 134a in it.
There are several Cons for running 134 in a 12 system, oil incompatibility being one.
Anyway........
for the measly $1,000 it takes to make the system right........ why take shortcuts?
Do you want to fix it once and be done with it?
Or
Do you want an ongoing headache that takes a little bit of money every year or so over time until your system fails anyway? Usually in the heat of the Summer!
Dave
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http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
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http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
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Howesight
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Joined: July 02, 2008
Posts: 3273
Location: Vancouver, B.C.
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| Posted: Fri Jun 24, 2022 9:25 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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Here in Canada, we have excellent availability of RedTek refrigerant which, I know, is just a mixture of very pure butane and propane, but the molecular size, like R-12, is large. It does not permeate out of R-12 rated hoses the way that R-134A does. I strongly recommend RedTek or a similar refrigerant for anyone keeping their factory R-12 hoses. That said, a leak is a leak and RedTek will leak out of a leaky system.
The R134A refrigerant runs at higher head pressures, which probably expands the R-12 rated hoses and thus expands any age-related fissures in the hose. Every older vehicle in which I installed R-134A into a system with R-12 hoses would only maintain pressure for a season at best. As a crude experiment, grab a 30-year-old used R-12 hose and bend it in your hands. Now try new barrier hose. There is no comparison - - old R-12 rubber hose makes your garden hose seem robust by comparison.
These R-134A converted vehicles were not Vanagons either, with the looooonng hoses! (A couple Explorers, a few Audi's, a Jetta). By contrast, my son's '87 Toyota 4Runner (420,000 kms!!) is still rocking the factory fill of R-12. The hose length in that old Toyota is quite short, with most of the system being hard lines. My old '88 4Runner, which I "converted" to R-134A and ester oil, would only hold pressure for half the summer and require re-filling mid-summer. On the occasion of the "conversion", all Schraeder valves, o-rings and the receiver drier were replaced with $tock Toyota factory parts. I think the small molecules were to blame. That '88 was sold many years ago.
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djkeev
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dart330
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Joined: July 19, 2004
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Location: Houston, TX
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| Posted: Sat Jun 25, 2022 7:33 am Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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I went through the same thing 6 years ago. If you want it to be reliable, go ahead and rebuild the whole system. Hoses, condenser, compressor, receiver/drier. It's not that bad once you get going.
You can see what I did in these posts
https://www.thesamba.com/vw/forum/viewtopic.php?t=672083
I also upgraded the wiring last year. Wasn't having any issues, but didn't want to risk melting the fuses.
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floodwood
Samba Member
Joined: October 22, 2017
Posts: 163
Location: Cambridge, MA
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| Posted: Sun Jun 26, 2022 6:12 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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Thank you for the responses here. I got a quote for 200 this week to convert the fittings to r134a, pull and check vacuum and leaks, and refill the system. I will report back.
My eventual route may be replacing the following per the threads here:
New compressor
New receiver drier
New parallel flow condensor
New hoses rebuilt at an a/c shop
Clean and rehab evaporator
My largest concern is the wiring for the fans - some people here appear to have reworked the stock wiring to include relays. Any advice here on wiring upgrades ? |
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djkeev
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Howesight
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Location: Vancouver, B.C.
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| Posted: Sun Jun 26, 2022 8:39 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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The problem with the wiring in the D-pillar, simply put, is that the wiring, relay and fusible link were all sized too small. They are all perfectly adequate for new blower fans, but for cranky older blower fans, the sizing is inadequate.
The proper fix is to remove and service the blower fans or replace them with quality new ones. There have been a number of good threads on this as DJKeev has pointed out.
The Vanagon AC system is a good one with a very large capacity evaporator. The main shortcoming has always been the fact that the driver and front passenger generally prefer chilled air blowing on them from the front. But the Vanagon system will do an excellent job of cooling the whole interior, when it is operating properly.
Rehabilitating the Vanagon AC system is a large job due to the grunt work involved, but it is not complicated. Why pay an AC tech to do work he/she hates at a shop rate when you can do all the important work yourself? I realize we don't all have the luxury of time or a nice shop, but if you do it yourself, you know the quality of the workmanship is excellent. I can't see why an AC shop would refuse to vacuum your system down and check for leaks and leave it with the vacuum in place. Then you would show up and dump some RedTek into the system before driving away.
By comparison, my Wife's Audi A4 climate control has a huge number of electronic failure modes and an evaporator that is literally buried in the dash and requires dash removal to access the evaporator for any replacement. Right now, I dump a refrigerant re-fill into it once or twice in the summer, but one day, I will have to replace that evaporator. It will NOT be simple. By comparison, the Vanagon evaporator, blower fans, etc, are easily accessed and the Vanagon evaporator almost never fails.
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floodwood
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Joined: October 22, 2017
Posts: 163
Location: Cambridge, MA
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| Posted: Wed Jun 29, 2022 8:31 am Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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The van is back from the A/C shop - Questions and Invoice are below.
Services rendered:
1. Change fittings to r134a
2. Pull and hold vacuum for 45 min
3. Dye in system to check for leaks
4. Refilled with ~3lbs of refrigerant.
Results:
1. I have moderately cold air! The interior of the van cools down with fan speed 4 and fan speed 3 will somewhat sustain that temp once cool.
2. See receipt for notes - the electrical on my A/C system appears to be pretty spotty. Among the issues noted:
i. A/C temp switch with snowflake turns system on, has a 'dead spot' in the middle that shuts the system off, then works when fully turned 'on'
ii. Rear fans (not blowers?) stay on even after the car is shut off. If i turn the snowflake switch at all, the system turns off (car off only)
3. A/C Readings
i. Low pressure: 35-40 psi consistently
ii. High Pressure, car not moving: sustained 200psi, peak 160 psi with radiator stage 2 fan coming on
Clearly I have some electircal work to do.
Using the below two threads as my guides, I have identified a few of the wiring upgrades that I need to make (summarized below). However, there are a few lingering questions I need help addressing
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
https://www.thesamba.com/vw/forum/viewtopic.php?t=...hlight=e35
1. Replace the right side wire lug to the fuse as it is barely adequate for the current it must handle
Here it looks like i need to change the actual eye fitting to the fuse to handle more current, but the actual wiring gauge (6.0) is adequate?
2. Replace Blower high speed relay #2 depicted in the above picture to a 70 amp relay. Originally the relay was a 40 amp and it was superceded with a 50 amp
I have a 1991 so I probably have a 50 amp relay. What exactly does this relay control - what fan speeds?
3. Add a 50 amp thermal breaker to the circuit.
This is being wired in series including the existing 50A fuse, or in place of the 50A fuse?
Additional Questions
1. What wiring changes do I need to make to safely use my fan speed 3 & 4? Some threads here have indicated use of additional relays. I am hesitant to cut stock wiring unless the solution is clear cut and a demonstrable improvement. Resistor, etc.
2. What/how does the A/C system with the Radiator fan in the front of the van? i.e. under what conditions does the A/C system trigger radiator fan stage 1 to engage and radiator fan stage 2 to engage. It is my understanding that the relays will turn off the A/C if the engine is hot enough to warrant rad fan stage 3 engaging
3. A/C fan speed 4 previously caused some A/C chatter as the multipurpose A/C relay would repeatedly engage / disengage. I am wary of fires so would like to diagnose this issue if possible. |
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floodwood
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Joined: October 22, 2017
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Location: Cambridge, MA
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| Posted: Wed Jun 29, 2022 2:17 pm Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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adding the invoice
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t3 kopf
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| Posted: Thu Jun 30, 2022 6:56 am Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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Well, if you have all 4 speeds working properly, that is already a big plus. To run speeds 3 and 4 safely, I would do at least the relay change and the front relay mod up by the radiator. I did those and I can run speed 4 all day without anything getting very hot back there.
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wasatch
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| Posted: Thu Jun 30, 2022 9:12 am Post subject: Re: 1991 Tintop Air Conditioning Rehab Attempt |
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| t3 kopf wrote: |
| Well, if you have all 4 speeds working properly, that is already a big plus. To run speeds 3 and 4 safely, I would do at least the relay change and the front relay mod up by the radiator. I did those and I can run speed 4 all day without anything getting very hot back there. |
Care to share the 'front relay mod' details on keeping temps down in 3/4 mode? |
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djkeev
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djkeev
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