Idle surge when a/c clutch engages

Recently my '01's idle started surging when the a/c clutch engages. It will actually pull/accelerate when this occurs. I searched and came up with what I think could be the problem, but want a second opinion.

The a/c clutch engages every 5-10 seconds which sounds like symptoms of low refrigerant. This has been happening for a while, but the rpm's never increased by 500 or so, and it certainly never pulled against my efforts to brake. I checked for vacuum leaks and for loose intake/exhaust bolts, but did not locate anything obvious.

Any help would be appreciated.

Thanks,

Brad

I'm pretty sure your idle is supposed to increase a specified RPM every time the A/C compressor is engaged. The computer does this through the AIC on the throttle body. What the specified RPM is, I don't know, but 500RPM sounds about right.

Yeah, my '00 does the same thing; even to the point where if I'm only not firmly on the brakes, it creeps forward during the "surge" when I'm stopped. Rightly or wrongly, I just ignored it considering its been like that as long as I can remember, maybe even since I rolled it off the lot brand new 6 yrs ago.

- Jay

I know what you guys are talking about, but this is a recent change from the idle increase you guys are explaining. My guess is that under normal conditions the computer increases idle when the a/c clutch engages to compensate for the drag that the a/c pump creates. The increase is usually seamless though, and is not high enough to cause a surge in the driveline.

Sometimes I am able to rev the engine in neutral and get it to go back to behaving like it should, but when I stick it back in drive, and the a/c clutch engages, it races back up again.

Does anyone know if when I rev the engine, the a/c system pressure increases? I plan on having the a/c checked for low refrigerant first, and then going from there.

Thank again,

Brad

OK. It ran fine today. So here's the difference. When the a/c clutch kicks in normally, all I hear is the click and the whir of the compressor(quiet and no rpm increase). When it is acting up, the idle jumps about 500 rpm when the clutch engages and the compressor seems to be louder.

Ideas?

I checked the low side pressure and it was about 35 psi which is supposed to indicate that the system is filled. While I was watching the a/c clutch engage and disengage I noticed that when the clutch disengaged, every few times it would drag and spin very slowly until it engaged again. Most of the time when it was disengaged, it would remain still. Is this an indication that the clutch may be going out?

As it stands so far....

1. a/c refrigerant seems to be charged.
2. a/c clutch drags a little when disengaged
3. idle surge is intermittent
4. idle surge is directly related to a/c clutch engaging
5. idle jumps about 500 rpm and causes the vehicle to lurch
6. a/c clutch/compressor seem louder when idle surge is present
7. I can rev the engine and usually correct the issue

Any other ideas would be greatly appreciated.

Thanks,

Brad

Anyone ever find an answer to this? I'm having the same issue on my new to me 99 Sport.

I would venture to say your A/C clutch may be on the dying end....

They are easy to replace, AND, sometimes can be done with the compressor still on the vehicle and lines still connected.....

Since your working with the pulley/clutch assembly, you won't be touching the refrigereant lines themselves..... That is why it can stay attached.....