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View Full Version : Ghost problem... Vibration with AC on. HELPPP!!!!


feraldarkness
2010-04-19, 08:12 PM
Been fighting a hell of a problem....

2003 chevy caviler, 2.2 ecotec, manual trans.

First brought in with a vibration when the AC is turned on, once the engine was warm, would vibrate even with the AC off, oddly, when I cleared the engine codes with a scanner it instantly idled better for a min, then went back???

So, checked the plugs, they were crap, replaced them, still the same problem.

Checked, fuel PSI, Compression, motor and trans mounts, and the AC compressor turns fine by hand.

Checked identifix / other mechanics, decided maybe its a balance shaft issue with timing, pulled the front cover and the hydraulic tensioner for it had blown its little cap off.

$900 timing/balance shaft chain job later, it idles perfect, all the time, however STILL VIBRATES with the AC ON!!! GAHHHH

So now I have a customer who is out some money, needs the car, and it still has 1/2 the problem.


Now I am thinking its electronics related, the PCM is not compensating for the AC or something, but unsure where to go from here, the data I have supporting this is as follows.

1. It does NOT idle up when AC is turned out, desired rpm stays at 900, actual RPM is 900 without and 875 with ac on.
2. It has AC request YES, when it is turned on.

Another important thing, when it has this vibration feeling with the AC on, it is constant through all RPMS, idle, 3k, 5k, still has this vibration.

Another question, can an AC compressor be out of balance? Rofl, never heard of that, but shit, I am kind of in a hard spot.

volksmech
2010-05-04, 12:45 PM
Been fighting a hell of a problem....

2003 chevy caviler, 2.2 ecotec, manual trans.

First brought in with a vibration when the AC is turned on, once the engine was warm, would vibrate even with the AC off, oddly, when I cleared the engine codes with a scanner it instantly idled better for a min, then went back???

So, checked the plugs, they were crap, replaced them, still the same problem.

Checked, fuel PSI, Compression, motor and trans mounts, and the AC compressor turns fine by hand.

Checked identifix / other mechanics, decided maybe its a balance shaft issue with timing, pulled the front cover and the hydraulic tensioner for it had blown its little cap off.

$900 timing/balance shaft chain job later, it idles perfect, all the time, however STILL VIBRATES with the AC ON!!! GAHHHH

So now I have a customer who is out some money, needs the car, and it still has 1/2 the problem.


Now I am thinking its electronics related, the PCM is not compensating for the AC or something, but unsure where to go from here, the data I have supporting this is as follows.

1. It does NOT idle up when AC is turned out, desired rpm stays at 900, actual RPM is 900 without and 875 with ac on.
2. It has AC request YES, when it is turned on.

Another important thing, when it has this vibration feeling with the AC on, it is constant through all RPMS, idle, 3k, 5k, still has this vibration.

Another question, can an AC compressor be out of balance? Rofl, never heard of that, but shit, I am kind of in a hard spot.


if it is a multi piston type of pump and one of the pistons is fucked then yes it could be the compressor. it would be no diffrent than a motor missing on a cylinder in theory. you should however be able to hook up you a/c guages and see if the high side needle jumps around quite a bit to test that theory i would think.