Idle problem when raining

[Tickle]

My 96 has been having problems when raining, it struggles at idle, recovers, then repeats several times. It doesn't die but it bogs down quite a bit.

No other idling problems during normal/dry conditions.

Any ideas?

 

[mwolson]

I suspect you are turning on your defroster when this happens. When you turn on your defroster, it automatically turns the AC on. When the AC compressor kicks on and off, the load on the engine varies a lot, causing the idle to change for a few seconds. I find my idle also goes up a bit when the AC compressor is on, including when I run the defroster.

It may be normal AC fluctuation or you may have an AC issue.

Did I guess right about the defroster being on when you have the problem?

 

[Tickle]

I think the defroster was on.

Why wouldn't I see similar behavior when I am running AC in warmer weather?

My AC never choked the idle down like this.

 

[mwolson]

I do see similar effects on my idle in hot weather with the AC on. It just is never as bad as you report with your car.

I am not sure what is going on with your idle, but it appears to be AC related.

 

[jmsa540]

tickle, how many miles are on your car?

have you ever changed the iac?

 

[Tickle]

88k miles. I replaced it once while chasing down a vacuum leak, but put the old one back after a weird humming/vibration in the air intake tube.

Most of my searches have pointed to IAC. Why in wet weather only?