Rpms fluctuate when im idling and i turn the air on

[deftsound]

I noticed today, and am not sure if its normal, that if im stopped and idling and i turn the air on the rpms will drop for a second then go up to like 1000 then back to normal. When i go from defrost all the way over to max a/c the car actually almost dies before it goes to normal rpms. When im driving and i turn it on it doesnt do it. I assume this is normal because the car has to turn the extra pulley to power the air and when its at idle its at a low rpm thus less power is available...

Is this normal???

 

[tomustang]

yes it's normal

 

[stangGT97]

yes it's normal

and annoying as hell

 

[squares98]

I dont think that is normal, I hgad that problem(search mity2's thread), I replaced the IAC and bad pcv valve and the problem went away.

 

[Orions98GT]

When the ac compresser clutch engauges it pulls power from the crank, so the engine slows down, then speeds itself back up. This will also happen on defrost mode.

 

[Twista]

yep its normal for the A/c to drag down the RPM's.

 

[helty]

normal
free post

yeah, its normal

 

[Mustang5L5]

It's normal to a point. It should only drop the RPMs 50-100 RPM as the A/C compressor kicks on and off.

If you are dropping 200-500 RPM then something may be wrong.

 

[triggz]

If its dropping too much it's probably due to the IAC.
Do you have the 'copper cap' mod, or IAC restrictor plate?

 

[Hunter-White]

Ha I noticed the other day that my rpms drop while I'm hit the power windows?!?! is that normal?

 

[40th GT]

Ha I noticed the other day that my rpms drop while I'm hit the power windows?!?! is that normal?

Funny, I noticed it too. In fact, the RPM drops whenever I use a power accessory. (move the power seat back n forth, move windows up/down..)

To the thread starter: It's nothing to worry about. Mine drops down to almost 500 before returning to idle. (IAC modded)

 

[69Rcode_Mach1]

Funny, I noticed it too. In fact, the RPM drops whenever I use a power accessory. (move the power seat back n forth, move windows up/down..)

To the thread starter: It's nothing to worry about. Mine drops down to almost 500 before returning to idle. (IAC modded)

Sounds like your alternator is struggling to give it juice.

 

[sgarlic]

Mine drops 200 RPM or so when I hit the A/C at first. Did it since I drove it off the lot..

 

[Dave0803]

yeah, mine drops when the cooling fans come on, power windows, and anything else that uses voltage. Mine has had a bad idle since the day I got it though. Do any of these things run smooth?

 

[Cantslowdown]

Mine drops with the A/C on but i havent run it in awhile I'll have to see how it works since its getting hot out side I tryed it awhile back but havent since..

 

[Stang|ess]

start your car with a cold engine, turn the ac on, and let it warm up. don't touch the throttle at all. after it reaches operating temps, turn it off and start her up. should help.