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A/C not working, please help...

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Old 07-28-2014, 12:02 PM
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Default A/C not working, please help...

So my a/c has been blowing ambient air on and off, until it finally just blows ambient air. This time in FL, especially with a 2month old, you need the a/c to work. Here's the back story...

Had a massive coolant leak, turned out to be a leaking heater control valve. Replaced it, flushed the coolant system and refilled. Still had a leak, but luckily it was simply the bleeder screw that wasn't fully tightened.

Cranked the car and no cold air. Ran the codes, and displayed a bad pressure/temp sensor G395. Made the mistake of trying to pull off the old one (only loosened it) before vacuuming the system and could hear the refrigerant spraying out. I quickly tightening it back the o-ring blew out and split. We ran a pressure test the next day and there was none. I had already picked up a new sensor, swapped it, and vacuumed the system. Vacuum held at -30 for about 15min, so we assumed that it was good and had no leaks. We tried to refill the system, but it won't take in any r134a. Also the clutch isn't engaging. The compressor is getting power (tested the wiring) and is hot to the touch. I've read it won't engage due to low refrigerant. We tried moving it manually and it won't budge. What is going on? Why won't the system take in any refrigerant when we try to recharge it? And does the clutch not moving have anything to do with it? Thanks for any help or ideas!
Old 07-28-2014, 04:34 PM
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Wait. So the clutch doesnt move, like the middle of the compressor will not turn by hand?? Then the compressor is seized up and junk. If thats not what you mean. You also must clear fault codes for the system to allow the compressor to come back on after its low on refrigerant. So you need Vagcom to clear the low pressure fault before the compressor is allowed on again.

Just so you know, You did nothing wrong removing the sensor with the system full. You need to remove it quickly, because theres another valve under it that will close as soon as the sensor is removed. If you would have just removed the sensor the leak would have stopped, you could have replaced the oring or sensor or what ever and never discharged the system.

Last edited by Prospeeder; 07-28-2014 at 04:39 PM.
Old 07-28-2014, 06:12 PM
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Thanks for your response. The middle portion will not move by hand, nor will it move when we take a wrench to the small bolt. The pulley does spin with the car running, though. I cleared the codes with my VAGCOM, and ran another auto scan just to be sure there were no faults. We vacuumed the system again for just over an hour this time, no leaks. We tried to refill the system with some r134a from autozone (no stop leak), and it won't take. All connections are tight, and no clogs in the hoses. Will the system not recharge because of the clutch being seized? Or is the clutch seized because the system has no r134? Please don't me I need to replace the compressor!
Old 07-28-2014, 07:24 PM
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If you cant turn the middle by hand the compressor is shot. Thats only if its a clutch type compressor

Edit:
Just realized, if your model is one without a clutch (which many are). They always run and a variable unit inside does all the pressure control. There are small arms that hold the outside pulley to the inside part of the compressor called a break away. So when the compressor seizes the belt doesnt just blow off, the arms shear and the outside spins freely.

Last edited by Prospeeder; 07-28-2014 at 07:36 PM.
Old 07-28-2014, 07:55 PM
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Sorry, it's a 2005 A6 3.2Q with just over 106k miles. Both the middle and outside pulley spin with the car running, does that matter? Or is it safe to assume the compressor is shot?
Old 07-28-2014, 08:11 PM
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That's pretty weird. Even with the car not running, simply due to the fact that the system is in a vacuum state, it should take, at least, 1/2 lbs. of refrigerant before you need to start it.

Do you have a manifold set that you can use to read the pressures?
Old 07-28-2014, 08:54 PM
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Really weird. It took in just over 100g and that was it. We calculated by weighing the r134 can before and after. We do have a manifold set, pressure was reading, if I recall correctly, 90psi while we tried to fill the system. We started the car, and turned the a/c to max low. Hooked up the r134 can, and opened the valve (tapped into the can). System takes in a little and the can gets cold, but just for a few seconds. The compressor never kicks in. I sat in the car and noticed the Econ switch/button is on. I tried switching it off, but it just stayed. I cleared the faults and took it for a drive around the neighborhood with the air set on 60, still no cold air. Am I doing something wrong here?
Old 07-29-2014, 05:59 AM
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Default Vacuum both high and low pressure lines?

Do I need to vacuum both the high and low lines in order for the system to charge? Also, where is the compressor relay switch? I saw the a/c fuse on the passenger side, but can't locate the relay switch???
Old 07-29-2014, 11:12 AM
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I personally had a leak on the G395. I had to take the bumper down and replace it. It worked. It was leaking through the electric connector pins... My C6 (113K miles, 2006, S-line).
Old 07-29-2014, 11:29 AM
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Originally Posted by emmm
Sorry, it's a 2005 A6 3.2Q with just over 106k miles. Both the middle and outside pulley spin with the car running, does that matter? Or is it safe to assume the compressor is shot?
Ok ok stop. You have a clutchless compressor. Its always running. There is nothing to "kick in" If the codes are clear, and the car is running it should start pulling the refrigerant in and everything working. If nothing is happening, like the low side and high side pressures do not change the compressor is either bad, or the climate head is not giving the variable actuator inside the compressor the signal to start doing its thing. Use Vagcom to check faults. Typically if there are no faults, and no pressure changes, the compressor is junk.


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