1998 Honda Civic Rough Idle when A/C is On

Tiny
TCHIEN69
  • MEMBER
  • 1998 HONDA CIVIC
  • 4 CYL
  • FWD
  • MANUAL
  • 150,000 MILES
When I'm idling and the A/C button (not just fan) is on, withing a few seconds, I start hearing clicking noises from the engine corresponding to sharp drops in engine rpm (so much so that I fear a stall), but it jumps right back up and repeats. Toggling the A/C button off immediately stops this behavior, but turning it back on restarts it. This used to happen sporadically, but now happens almost all the time when idling. Thanks.
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Monday, August 3rd, 2009 AT 5:23 PM

3 Replies

Tiny
KHLOW2008
  • EXPERT
Hi tchien69,

Was any repairs carried out prior to this happening?

What is the idling speed?

Are both cooling fans working?
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Friday, August 7th, 2009 AT 3:11 PM
Tiny
TCHIEN69
  • MEMBER
Thanks for replying. Sorry, for the late response. I'm been waiting for it to happen again so I can answer your questions more accurately, but miraculously it hasn't! I'm wondering if it only happens when the outside temp is above a certain level. I know the weather's been cooler in Dallas, TX since I posted (high's of mid-low 90's vs. High 90's / low 100's).

1. No repairs.

2. The markings aren't very detailed below 1 k RPM, but I'd say usu. 0.5-0.7 k RPM.

3. In general or during the rough idles? As far as I know, they're working in general. I know the engine temp stays constantly right at the middle of the gauge with no noticeable variance once the car's warmed up regardless of outside temps.

I'll update if it happens again.
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Tuesday, September 1st, 2009 AT 3:45 PM
Tiny
KHLOW2008
  • EXPERT
The symptoms described is indicative of the AC compressor cutting in and out. This could be due to low idling speed.

Possible causes for low idling speed with AC on could be the IAC. Idling speed should be 700 and if it is lower than that, cleaning the throttle body and IAC should solve the problem.
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Wednesday, September 2nd, 2009 AT 8:42 AM

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