A/C and boost levels.

For the past couple of weeks I have had a problem with my a/c. I works fine in the driveway (35 deg at the vents) and cruising around town. When I demand higher boost levels (on-ramps for the freeway, accelerating from lights and up hills) the system shuts the compressor off. When the engine goes back to normal load the a/c comes back on. This is especially worse when towing. I know the ecm is connected to the a/c. My max boost is around 19psi-just like most of us here. The system shuts down when the a/c pressure goes above 464psi but the fans are working fine and rad and condenser are clean. I checked the system with a Snap-On ($18,000) machine and the high and low pressures are fine and there are no leaks. The fans pull hard. The a/c is great until I go over about 15psi. Anybody have any ideas?

I think this is by design, it's a "load shedding device" that is giving you more power for acceleration when you ask for it. I don't know of a way to override it either!

Cool! I haven't noticed it on my Jetta yet, but I haven't had the a/c on much until the last few days.

My old '93 Saturn SL had the same system. Whenever you floored the gas pedal, the a/c compressor shut off. However, if you kept if floored (long hill) the a/c would eventually turn back on (after 10 seconds or so). It was desperately needed, too, as with only 85hp, that car was a total dog with a/c on and a few passengers. My Jetta seems to ignore the a/c load.

Chris

Originally posted by aaron:
I think this is by design, it's a "load shedding device" that is giving you more power for acceleration when you ask for it. I don't know of a way to override it either!

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Hi Mike

I just got my AC checked at the dealer and he was telling me that it may shutdown during acceleration in order to preserve the HPs. He told me that it could act like this and it was by design.

ST

Actually, it doesn't merely shut off, but it varies its cooling effort. Because of this, it's no use for the driver to shut the compressor off periodically to save gas, the car does it for you. If you set the fan to "1" and adjust the temperature, the A/C will do its best to save fuel all on its own. Do a search for "variable", "compressor", and "mickey", for a nice explanation.

I do not think that I'm hunting for too much power. It even happends on small grades. If I use more than 10-15% pedal input it shuts down. The main reason why I ask is because it only started doing it this summer. I have a bud that has a 2002 Jetta TDi and drives like he stole it. The A/C never quits and he is set up just like me. If I would follow that rule I would have to leave it off all the time. This is not a normal function of the A/C-if it was there would be mutany at VW. I have heard of cars that cutback on the A/C when on the floor, but not for day to day driving.

[ July 02, 2002, 13:20: Message edited by: vworks ]

I've recently noticed that when starting off in 1st gear from a stop, while running a/c, its real easy to kill the engine. It's caught me off guard a couple times.. just shudders then dies. I also noticed that is seems to cause a delay in boost. It just got warm up here so maybe I just forgot from last year, has anyone else had a similar problem?

It did not do that the first and second summer that I had the car. This is the first season it is doing it. I have not changed my driving habits or added any mods to the car. On these hot days it is not hard to get the boost into the teens so it is a frequent occurance. I was thinking there was some way to change this feature with VAG/Com but it just started doing it this summer.

I did a long 6 mile run of %6 grade up, on a 90 degree day. High altitude with extream heat and the ac on is real bad. Its better yours knows when to shut off. The pipe from the turbo to the intercooler was burning hot and the after the intercooler was about 140 degrees. My advice kill the ac when you need the power

97 jetta tdi
TT Exhaust, Upsolute, K&N,