Ok guys i'm trying to get this figured out so when i drive this thing cross country in august i don't die of heat exhaustion....

The AC system isn't working and i have got it traced down to something to do with the relay. If i jump across the relay the system kicks on and works fine. If i take the relay out and test it manually it works fine but in the car it doesn't work. I have power to the one side of the relay trigger and i'm assuming the other is ground but the wire isn't brown its black with a white stripe i believe, so i'm assuming the car triggers with ground but i'm not sure... My manual doesn't show where or what the negative side of the relay trigger goes to and this is where i'm lost. The wire goes to ground if i ohm it out but its got like 4ohms resistance so its not a straight path to ground.

Does anyone have any idea what i'm missing here?? What controls the relay? does it do it with pos or neg? Is there a better wiring diagram anywhere easy to find... Thanks for the help guys!

 

Anyone?? Im open to all ideas at this point lol

 

Probably a high or low pressure condition on the switch (which is located on the passenger side of the condenser-- the black radiator in front of the coolant radiator). Ive heard of them going bad, else you have too high or too low of pressure, if it was blowing cold when you jumped it then it probably isnt low pressure. If you currently dont have access to a VAG COM right now, if it were me and you really NEED the A/C, I would find a parts store, get a pressure gauge (very cheap, and the fittings are right next to the battery), connect it to the low pressure side (make sure the A/C is running when you check it), make sure the pressure isnt too high and you could safely run the A/C as long as you manually cycle it intermittently.

Obviously it would be best to use a gauge to be fairly certain that there isn't actually too high or low of pressure, both can cause serious damage to the A/C system.

EDIT: Basically, it sounds to me like the relay is fine, it just isnt being signaled, as far as I know BASICALLY the only reason it wont be signaled to come on is because of the pressure switch. The other reasons are only intermittent (e.g low engine speed, kick down switch closed). The other small possibility is that your HVAC head unit is bad, but I doubht it. I also just re-read your post and your not on your trip YET, so basically try and find a VAG COM.

EDIT again: I just realized you really cant permanently jump it because the A/C is cycled when it is operating correctly. So if you wanted to ghetto run it, you wouldnt want to run it continuously. One option is to jump the pressure switch, making it think the pressure is normal. The only thing is I dont know if the pressure switch is used to determine when the compressor should cycle, if it were, it would be the same thing as permanently shorting the relay and you wouldn't want to do that.

 

I have a VAG Com and when i had it hooked up last i swear it didnt say anything about AC problems... Ill have to check it out again and see

 

Make sure your checking the HVAC and not engine.