VW aircon logic - troubleshooting
Discussion
Ye gentlemen of much worldly knowledge.... any of you familiar with VW AC systems?
I have a 2001 polo GTI 6n2 with climatronic.
The AC has not worked for about 10 years but I would like it to work. I had it re-gassed a while back but there was already gas in it and the problem was not resolved with fresh gas.
If I turn the AC on inside the car the engine revs pick up from idle which is to be expected but if I put a probe on the AC clutch wiring I do not get a signal. I would also expect the rad fan to come on slow with the AC compressor but it does not.
Trying to work out how "smart" the AC system is - what else is in the logic tree that could be preventing the AC clutch getting power? What other sensors are there in the loop? Are there solenoid valves in the refrigerant loop?
There is a fan control module under the front left headlight which seems to be part of the system - mainly to control the engine cooling fan. I have replaced this in the hope it might help - it did not. I also replaced the cooling fan as one of the coils in it had burned out.
Its an old car - I get that - but VW are lazy and a lot of the components don't seem to have changed much over the years.
I do wish VW would provide wiring diagrams etc for the older stuff as I am sure the fix is fairly simple if I can find the fault. Does anyone have access to the legacy VW workshop manuals?
Any thoughts on the best process to debug this?
If I temporarily bypass the control system and power the AC clutch directly should I see a change in temperature?
P.S. I scanned the car and the the only fault codes relate to the V71 stepper motor for the recirculation flap. Eveything else seems to check out ok
I have a 2001 polo GTI 6n2 with climatronic.
The AC has not worked for about 10 years but I would like it to work. I had it re-gassed a while back but there was already gas in it and the problem was not resolved with fresh gas.
If I turn the AC on inside the car the engine revs pick up from idle which is to be expected but if I put a probe on the AC clutch wiring I do not get a signal. I would also expect the rad fan to come on slow with the AC compressor but it does not.
Trying to work out how "smart" the AC system is - what else is in the logic tree that could be preventing the AC clutch getting power? What other sensors are there in the loop? Are there solenoid valves in the refrigerant loop?
There is a fan control module under the front left headlight which seems to be part of the system - mainly to control the engine cooling fan. I have replaced this in the hope it might help - it did not. I also replaced the cooling fan as one of the coils in it had burned out.
Its an old car - I get that - but VW are lazy and a lot of the components don't seem to have changed much over the years.
I do wish VW would provide wiring diagrams etc for the older stuff as I am sure the fix is fairly simple if I can find the fault. Does anyone have access to the legacy VW workshop manuals?
Any thoughts on the best process to debug this?
If I temporarily bypass the control system and power the AC clutch directly should I see a change in temperature?
P.S. I scanned the car and the the only fault codes relate to the V71 stepper motor for the recirculation flap. Eveything else seems to check out ok
plenty of places to get wiring diagrams
https://www.autodata-group.com/uk/
https://www.factory-manuals.com/shop/2001-volkswag...
https://easymanuals.co.uk/product/vw-polo-workshop...
https://haynes.com/en-gb/volkswagen/polo/1999-2001...
https://www.alldata.com/us/en/support/repair-colli...
and no doubt there are many more.
https://www.autodata-group.com/uk/
https://www.factory-manuals.com/shop/2001-volkswag...
https://easymanuals.co.uk/product/vw-polo-workshop...
https://haynes.com/en-gb/volkswagen/polo/1999-2001...
https://www.alldata.com/us/en/support/repair-colli...
and no doubt there are many more.
A pressure switch is something that'd be inside the control logic - if detected either too low or too high then the A/C would be disabled.
tegwin said:
Any thoughts on the best process to debug this?
If I temporarily bypass the control system and power the AC clutch directly should I see a change in temperature?
Yeah, certainly worth a try.If I temporarily bypass the control system and power the AC clutch directly should I see a change in temperature?
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff