a/c dead or aux fan dead?

clancy · 04-25-2012, 06:47 AM

My kid poked a small tree branch through the a/c radiator. It looks like it only separated the cooling vanes (?) on the a/c radiator. Meaning it does not look like it broke the actual cooling tubes. There is no oil staining on the exterior of the radiator as I thought you got from the lubricant in the coolant if it leaked out from break in the radiator.

Anyway, the electric fan does not come on when the a/c is on and the air does not get cool at all. It worked fine prior to the tree branch incident. It is my understanding that if the coolant is below an acceptable level the air compressor does not come on and the electric fan does not activate. Is this correct?

Also, the tree branch incident did not penetrate to the coolant radiator, but that radiator had to be replaced as it sprung a leak where the plastic tank on the end started leaking. So the car must have taken a significant bump. He spun out on the road avoiding a deer and ran off the road. Anyway, I replaced the coolant radiator. But did not properly attach the upper radiator rose. It blew off later and the car lost the coolant and overheated for a couple of minutes. During this time the aux fan never came on. So maybe the a/c is not coming on because the aux fan is not working?

Is there a way to verify this with a VAG COM?

Thanks

turbo510 · 04-25-2012, 12:10 PM

VAG-COM will run the electric fan as one of the output tests (I think when checking the HVAC module). This fan should run during an over-temp situation, so the status of freon pressure shouldn't matter. Does the AC compressor clutch click on when you select AC? One way to see if the freon leaked out or not is to remove one of the caps over the test connectors, which have Schraeder valves, and tap the valve to see if you get a puff of gas. That won't tell you if there is enough to cool, but will tell you if it all leaked out.

clancy · 04-28-2012, 12:06 PM

I am embarrassed. I ran the VAG-COM scan and got the 00792 A/C pressure switch F129 open or short to ground. Removed the bumper and sure enough the switch was unplugged. My bad. Forgot to plug it back in after replacing the coolant radiator. Sure is simple when you remember to do the basics, like using the tools at hand.

turbo510 · 04-29-2012, 12:40 PM

Aways nice when its that easy!

04-25-2012, 12:10 PM	#2
turbo510 AudiWorld Senior Member 2007 Volkswagen Touareg My Garage Join Date: Jun 2008 Location: Yorba Linda CA Posts: 1,443	VAG-COM will run the electric fan as one of the output tests (I think when checking the HVAC module). This fan should run during an over-temp situation, so the status of freon pressure shouldn't matter. Does the AC compressor clutch click on when you select AC? One way to see if the freon leaked out or not is to remove one of the caps over the test connectors, which have Schraeder valves, and tap the valve to see if you get a puff of gas. That won't tell you if there is enough to cool, but will tell you if it all leaked out. __________________ 1996 Audi A4 2.8 1972 Datsun 510

04-29-2012, 12:40 PM	#4
turbo510 AudiWorld Senior Member 2007 Volkswagen Touareg My Garage Join Date: Jun 2008 Location: Yorba Linda CA Posts: 1,443	Aways nice when its that easy! __________________ 1996 Audi A4 2.8 1972 Datsun 510

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04-28-2012, 12:06 PM	#3
clancy AudiWorld Member Garage is empty, add now Join Date: Jan 2004 Location: Conifer CO Posts: 150	I am embarrassed. I ran the VAG-COM scan and got the 00792 A/C pressure switch F129 open or short to ground. Removed the bumper and sure enough the switch was unplugged. My bad. Forgot to plug it back in after replacing the coolant radiator. Sure is simple when you remember to do the basics, like using the tools at hand.