A/C works intermittenly need help

[SteelyS6]

A/C works great lots of airflow and blows cold. Last couple days it will stop working and get stuck on econ. Worked yesterday morning but stopped on my way home. Checked auxilliary elec fan when i got home and it wasnt working. Got the bentley out and checked all fuses. Pulled dash and starting pulling relays. Keyed ignition and sounded like a relay clicked on again and then started and A/C worked. Worked for ten minutes this morning and then quit again. Sounds like a weak or faulty relay. (1) Is this the 267 relay failing or a different relay? (2) Can this relay be found at Napa or do I have to purchase a 100 dollar relay from Stealership? (3) Anything else to check or other suggestions? Thanks for the help in advance!

[Scotty@Advanced]

What are the codes (DTC) for the A/C?

[SteelyS6]

Didnt actually check for codes. I guess I should have. Have ECS tuning scan tool so I will try that later when I get home. Update went out to grab my coffe cup and for shits and giggles turned car on and A/C working again.

[Scotty@Advanced]

Sounds like you've got an overpressure situation.. Codes will record this.

Didnt actually check for codes. I guess I should have. Have ECS tuning scan tool so I will try that later when I get home. Update went out to grab my coffe cup and for shits and giggles turned car on and A/C working again.

[mithril]

When AC is working, is your aux fan going? Do your water or oil temps rise just before the AC cuts out? Does this happen when only when you're stationary or also when the car is moving with good airflow? If the car is overheating because the aux fan is not working then AC will automatically be shutoff to reduce heat transfer into the oil and coolant in an attempt to prevent the engine from overheating.

[Zachariah]

I'm betting it's the G65 Pressure Sensor, located just underneath the passenger headlight. That sensor controls A/C compressor cutoff, after-run pump function and highest fan speeds, on BOTH auxilliary cooling and condenser fans. If it fails....your car will overheat, no matter what. VAG it just to be sure....

[mithril]

Based on the OP's profile he has an S6 so there is no after-run function, no AC condenser fan and only one electric fan. The 2.7T is the only engine in the C5 range that has fan after-run.

[SteelyS6]

Yup have an S6 and she's pissing me off today. Drove all last eve with A/C working and then it quit again right as I was getting home. When A/C is working the elec fan is on and when it quits its off.
Elec fan and A/C shutting off randomly while both driving and stationary. Car doesnt seem to be running hotter on coolant or oil temp than normal. This morning as well my backup alarms became stuck on when in reverse, aargghh! Tried reading codes with ECS Scan tool this morning but was unable to get it working. Where can I buy a proper VAGCOM cable and software, cause the ECS scan tool was the biggest waste of money, wont communicate in Can Bus and doesnt even recognize the proper VIN of my vehicle or reset the service light.

[eejimm]

If you are serious about your car, get a real one from www.ross-tech.com - pricey, but it just works. I use this one - http://store.ross-tech.com/shop/VCHUC.html - with a Win-XP tablet (Toshiba) but any good laptop with a USB port will work. You can get a clone on ebay cheap, but you get what you pay for IMHO...
Jim

[SteelyS6]

After searching around a bit I think post #9 on the this thread here might be worth looking into. (1) Incorrect charge of refrigerant. (2) faulty pressure switch.
http://www.audizine.com/forum/showth...ways-on-advice

Definitely want to look into a proper vag com cable and software for laptop.
Going to have the A/C charge checked this week and monitor the temps and occurrence of econo coming on.