RPM flux when accelerating and ONLY with A/C is on ?!? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 08-24-2003, 04:02 PM   #1
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Default RPM flux when accelerating and ONLY with A/C is on ?!?

Anyone else experience this problem? It is the ONLY thing I can notice that isnt quite right with my car at 160,000 miles. For some reason, with the A/C on, under acceleration the RPM'* will fluxuate while acclerating. It'* actually more like its accelerating in "bursts" of 300-500 RPM'*, depending on how hard I've got my foot down, but it definetely levels off in between the bursts. You can actually feel the loss of acceleration power in the car when this happens, and you can also feel the bursts in your seat. It will literally move you back and forth as it climbs. Not DRASTICALLY, but enough to notice. The A/C blows nice and cold as can be, and the compressor seems to be functioning great.

Anyone else experienced this or have any ideas as to what it could be?!?

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Old 08-24-2003, 04:25 PM   #2
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Wait until the engine cools down, and try turning the compressor by hand to see if there are any places that it catches or hangs up, or if it is difficult to turn.
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Old 08-24-2003, 11:21 PM   #3
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with the car off though, the clutch will be disengaged so spinning it freely wont really tell me much. It almost seems like something ignition realted to me, but its just sooo wierd that as soon as I push that A/C button on my cliamte control and **** it off, even in the middle of acceleration, the problem completely stops. Its not really a huge problem, just more of an inconvience. I've actually found myself shutting off the A/C to pass people and on highway on ramps, and then turning it back on, which I shouldnt have to be doing Its done this for a while now, possibly since I've owned the car, however it does seem to get a little worse each summer...

Noone else out there has ever experieinced this? Usually any problem I have and post, at least 5 others have gone through it. I figured this was something common?!?
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Old 08-24-2003, 11:38 PM   #4
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Have you ever watched the compressor operate? The center only spins when the clutch is engaged. That is the part which you must spin, not the pulley on the outside. You do not need to take the belt off to spin the center.
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Old 08-24-2003, 11:41 PM   #5
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Default hmmm..

I have the same problem with my 87 toronado... EXACT sytoms..
Only code my DIS gave me was EGR... still havnt fixed it.
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Old 08-25-2003, 12:21 AM   #6
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Originally Posted by CDecker
I've actually found myself shutting off the A/C to pass people and on highway on ramps, and then turning it back on, which I shouldnt have to be doing
I don't know about you, but my AC always shuts off when I go to pass someone. Anyone have any clue as to the difference here???
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Old 08-25-2003, 12:26 AM   #7
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Ahh yes, your talking about when it actually seems like it changes vents for a few until you let up on the gas?!? I've got that too, but thats a whole other issue I guess. Its done that from day 1 too. Climbing a long hill, passing, anything where there is heavy acceleration, the A/C seems to stop, and the front vents seem to shut off until you let up. Are you talking about that??
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Old 08-25-2003, 12:32 AM   #8
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Ahh yes, your talking about when it actually seems like it changes vents for a few until you let up on the gas?!? I've got that too, but thats a whole other issue I guess. Its done that from day 1 too. Climbing a long hill, passing, anything where there is heavy acceleration, the A/C seems to stop, and the front vents seem to shut off until you let up. Are you talking about that??
I'm talking about the WOT A/C cut-off. i don't know about the vent'* changing, but when i go to pass someone, and yes the majority of my passes are completed at WOT, the A/C is automatically cut-off
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Old 08-25-2003, 12:34 AM   #9
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At WOT the compressor is supposed to shut off.

Your problem with the air being redirected to other vents could be a small vacuum leak. I have had two other cars do this, but I never bothered to look for the problem. But with one of the cars it progressed into the vents being stuck at the defrost for longer periods of time.
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Old 08-25-2003, 12:36 AM   #10
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Yup, sounds like the same thing. I wonder how many others have noticed this, and if theres a fix? You dont seem to get a pulsing with the A/C on under accel though right?
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