A/C Help

[Dave65386]

Hi,

I have a Eurovan 2003, had it 3 years and the A/C has never worked. Not a problem in winter, but coming into summer again I feel I may be pressured to get rid if I can't get it fixed. There are loads of topics on this and I am pretty sure I have read them all, just can't find a solution.
Symptoms: No A/C, LCD flashing on start up.
Here's what I've tried:
VW Eurovan mechanic, they apparently made sure that the system was filled and there was nothing wrong with the clutch and compressor, but they couldn't find anything else wrong and couldn't work it out. So not sure if I trust what they say they did. However, I am assuming for argument's sake that the compressor, clutch and pressure are all good.
Checked for codes, the VAG reader I have says there are no codes, but not sure I trust it as the LCD is flashing.
Checked fuse A6, all good.
Checked Relay 114, all good.
Checked fan resistors, they looked ropy so replaced. Now when I replaced them, the fans still didn't come on, but after I played around with the relay, they did. This may have been because of the setting that I put the climatronic on though, initially when I was testing I just had it on LO, this morning when the fans came on I had it on Auto.

So now fans are running at least, but the LCD is still flashing and no power is going to the compressor clutch, I used a multimeter on the cables going to the clutch to test and there was no voltage.

Any other ideas?

Thanks for getting this far.

[rocknroj]

Perhaps the ac pressure switch.. A cheap part to swap. Most of the modern cars have a variable displacement compressor. Meaning that the compressor runs and instead of cycling on and off the coolant flow varies. Its on the low (suction side) of the system. It can be replaced without discharging the system.

Here is a link the part..

https://europarts-sd.com/achilowpressureswitch1995-2003.asp

[Dave65386]

Thanks rocknroj. I have read that you can jump 1 & 2 on that part, or the connector to it anyway to test whether it's the pressure in the system that is the problem. When I jumped it nothing happened. However, the fans weren't spinning either at that point. Have to get at 114 again to see if there is a lose connection somewhere. I think I may have a number of issues. I will keep at it, but any other suggestions appreciated.

These are the wiring diagrams that I am using to trace the problem.[/img]

[Dave65386]

At the top of the 2nd wiring diagram, there is a dotted area that says Fuse relay panel (behind left side of dash), within that there is a box that says AC Control Module. Does anyone know what that looks like? Trying to trace the power back from the clutch. Thanks in advance

[trunnion]

[Dave65386]

Thanks so much trunnion! Struggled to get any diagrams for my model. From what I have ready that relay is the only difference between the models, fingers crossed. Do you know what drives J365? What would cause the relay to shut off the AC?

[[email protected]]

Also there is a temp like sensor in with the temp and gauge sensors that directly effects the A/C

I had messed with mine when replacing one of the sensors and knocked it loose.
No A/C
re installed I got A/C

Did all the stuff you did and was ready to give up.

But it was found and am set now
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2001 eurovn weekender 207k fresh batteries

[Dave65386]

Thanks samscholz96, where was that temp sensor?

[Abscate]

ROSSTECH makes the definitive tool for troubleshooting this stuff as it can read out block data - much better than any scan too.
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🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🍊 🍊 🍊

[[email protected]]

In the thermostat housing
The middle one

2001 VR6 24v there are 3 sensors
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2001 eurovn weekender 207k fresh batteries

[Dave65386]

Abscate thanks, I'll look into getting one of those.

samscholz96 sorry if I'm being stupid, where is the thermostat housing? Thanks

[[email protected]]

Look from the bottom looking up between transmission and engine you can see the 3 sensor,s with harnesses attached to them.
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2001 eurovn weekender 207k fresh batteries

[Dave65386]

Great thanks, I will get under and take a look. Just as soon as it stops raining!

[rocknroj]

Been dealing with A/C issues myself.. Older car, not climatronic but theories of operation remain the same.

Those theories apply across vehicles and manufacturers. No, the EV is not unique in every aspect. Lots of info on A/C.. Here's some of what I learned.

The pressure switch is also called the trinary switch and it protects the compressor when pressures are wrong. The output is a sine wave kind of thing so really not easy to bench check without a scope. Some vehicles have ones switch for both high and low issues and some have separate high and low switches.

The various control units interpret the signal and if its out of spec, the clutch won't engage. It protects the compressor from running dry (low or emtpy charge) or overly high pressure problem ( an overcharge). This also creates a problem when trying to charge a system that is low. What came first, the chicken or the egg? The link reference at the bottom discusses how to over come this.

There must be a feedback loop somewhere in the system that prevents the clutch from engaging when the fans are not running but I have not been able to figure it out.. Perhaps a ground going high?

A/C compressors don't like sitting around not being operated for extended periods of time. You can provide 12 volts to the compressor directly to see if the clutch engages and listen for a click. Do so with the engine off. Just need to find the harness connector to the compressor. Be careful trying to disconnect it so you don't break the connector. Lots of them are squeeze and push back thing but are really tight and hard to disassemble .

You do not want to run a compressor dry so your first step should probably be to pick up a gauge set. They are pretty cheap.. I got one at harbor freight that works pretty well. It is not a daunting task to check the A/C charge levels.. Lots of info on how to use these things. The one I purchased even came with some instructions. There is on there website to download instructions as well so you can read before you buy. I think this was better than most on amzn

https://www.harborfreight.com/r134a-ac-manifold-gauge-set-58776.html


The A/C systems have lots of safety mechanisms because of the high pressures that are generated as well as to protect the compressor. The website below goes into a lot of detail on A/C and cautions about what not to do.

https://ricksfreeautorepairadvice.com/how-to-recharge-car-ac-when-the-compressor-wont-engage/

FWIW. My trinary switch blew its top when the cooling fan got stuck. I had no air flowing over the condensor while the compressor was running.. Only took a few seconds for the big disaster. So best to use extreme caution when messing with the A/C system.


-R

[Dave65386]

Thanks rocknroj. Lots of material to research there. I would def not play with it myself, but taken it two garages, one claiming to be an EV specialist, both have given up/got bored. I will not be daunted. When I bought the van, before I was wiser on A/C issues, there was a switch installed to manually turn the compressor on and off. So this problem has been there for a long time.

[kourt]

By your description, your system is VW's Climatronic, which is an excellent system when it works, but I have only worked on their manual control systems.

For AC systems, think of the following items as consumables:

compressor
condenser
expansion valve
receiver/drier
all o-rings
trinary switch

Whenever I get a new car and I'm working on the AC, these are the must-replace items on my list. My order of work is thus:

1. evacuate the system properly of all old refrigerant and do not plan to re-use any old refrigerant.

2. remove the components listed above.

3. flush the system with AC flush or acetone using a simple compressed air + bottle flush tool. Pay special attention to flushing the evaporator lines going in/out of the Eurovan firewall.

4. Install all components properly. Your new compressor should come with the correct amount of oil (135cc), and no additional oil will be necessary unless you have the additional rear AC in your van, in which case an additional 105cc is required.

5. Vacuum the system for a short time (45 minutes) and test for leaks by watching the gauge needles. Then vacuum the system for two hours. Time does not matter so much as how close you get to a perfect vacuum. Good vacuum pumps should always have fresh vacuum pump oil, so change your pump's oil before you start the vacuum process.

6. Once the vacuum process is complete, install your first can of air in the high side with the engine off. It will go in easily and this will allow you to get the compressor to actuate with some refrigerant in the system.

7. Be sure your high side valves are closed, and start the car. Turn on the AC and put a thermometer in your vent.

8. Fill your system by weight of refrigerant to the charge indicated in your engine bay, erring on the low side of any +/- weight range listed. Look up your values in Erwin if you no longer have the refrigerant sticker in your engine bay. Use a scale and try to be consistent in how your cans sit on the scale, because you also have the hose affecting the weight--but you can still witness and measure the weight of the can on the scale, despite the data contamination by the hose.

You can also fill by vent temp and gauge performance, and these other feedback values should all support a system filled properly by weight.

This should get you to 40F vent temps and a proper charge. I usually put in one can with dye so that I can find any leaks later--sometimes a little tightening on some joints is needed.

The beauty of the Eurovan AC system is that they document all torque values for all joints in Erwin, so there is really no guesswork.

These are all the basics. Search around on The Samba for Climatronic specific feedback--I know there are some posts about temp sensors unique to the Climatronic that are prone to breaking the AC circuit due to simple failures. Start with this thread.

kourt
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2001 Eurovan Winnebago Camper

[Dave65386]

Hi, update on progress or lack of it. Short of replacing the whole system I have followed most of the advice, but not got anywhere.

I bought a ROSSTECH reader, but the software didn't pick up any codes even though the Climtronic system flashes for 15 secs to show there is a fault. This is really curious, could it be an issue with the head unit itself? Some of the LCD screen is dead, so v old.

I have replaced the trinary switch, no change.

I had previously replaced the fan resistors, so they are new.

I checked connections to the clutch, the ground was dodgy, so replaced that. I supplied 12v direct to the clutch with the engine off and heard a very faint clicking, so I believe that is engaging.

I have checked relay 114 and all good, with the relay slightly pulled out I check the output voltages and they were fine. I checked 140 and all looked good inside, though it was so tight I couldn't check the output voltages.

So at the moment, I turn the car on, Climatronics flashes for 15 secs, fans don't come on and there is no power to the clutch.

HELP!

I have not managed to locate the thermostat sensors that samscholz96 mentioned, any photos of where they are would be wonderful. I understand there is another sensor on the passenger side of the rad, think I have found it, any way of testing that?

Also I do not have a relay 147 that trunion mentioned, can't see that it has been bypassed at all or that it ever was there.

[kourt]

Erwin HVAC repair guide, which has extensive Climatronic diagnostic info.

Some videos:

https://www.youtube.com/watch?v=XxezMRpNLsw

https://www.youtube.com/watch?v=K_TF5lti0Ks

https://www.youtube.com/watch?v=l7VqAXVe8LU

kourt
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2001 Eurovan Winnebago Camper

[Dave65386]

Thanks Kourt! Appreciate all the info, will take a look.

[Dave65386]

Progress!!!!

After much testing I have traced it back to the CCM, T28a/ pin 19 to be exact.

This feeds the AC pressure switch low pressure and the AC cut out relay.

Even though all the sensors seemed OK and all the relays seemed OK there was no power coming out of this pin.

Possibly recklessly, I provided 12v to this line to feed the above switches and bingo! Cold air, at the front at least, not the back yet, hoping that if I run it for a while it will work back.

The fans seem to be kicking in appropriately so think all safety systems are working OK.

I will either get a replacement CCM off eBay or install a separate AC switch.

Anyone want to scream "Don't do that you crazy man!!!"