a/c messing engine up

[eugenesxyby999]

I noticed that when my car is on, and when its fully warmed up to the normal temperature that it should be at, if I turn on anything related to a/c/fan, my rpms drop to 200-300 and rapidly jumps in that range until I hit the gas to push it back up.

I just turn my a/c off because Im worried that my engine might just die on me on the street.

Any suggestions?thoughts?fixes?

would be very much appreciated if you can help.

 

[turbotalon31]

It could be a possible bad iac ( idle air control motor ) .

 

[eugenesxyby999]

also I forgot to mention that my temperature gauge goes up as well.

 

[turbotalon31]

the temp goes up when the idle drops ? have u tested the battery and alternator ? when my gf alternator took a crap the temp gauge went nuts as well as the idle.

 

[eugenesxyby999]

yes the gauge went up, and idle dropped down. your saying a battery can do this?

I think the battery is perfectly fine. I had a light on for 24 hrs which killed my battery, after I jump started it, it was completely fully charged.

 

[95blackGsTurbo]

Odds are your compressor is starting to go out and loading up the engine more than the ECU is expecting so it can't compensate properly. Does it still blow cold? You should check the system pressure to be sure that it is functioning properly first. But 9 times out of 10 when we have a car come in here with this problem, it is related to the compressor starting to get harder to turn than normal. The other time it is the ECU not kicking up the idle.

 

[eugenesxyby999]

it still blows cold. I think the car is loosing pressure somewhere. I wish there was someone on this forums who owns a shop who specializes in DSM's only

 

[nctsiawd]

Sounds like a bad isc/iac...

 

[Tanro]

You could have any number of problems.

Bad Idle Air Control :

If you turn the AC on and the rpms fluctuate, or if your rpms surge, then fall but when you turn on the ac it doesn't do this.

Bad Alternator :
I have had an issue where my alternator started to die but was not totally bad, it would cause the Temp Gauge to Jump sporadically, turning on your ac puts more a load on the system. A dieing alternator can be diagnosed when your battery dies if you constantly run the ac.

Bad AC Pump
Your ac pump could be cause more of a load on the system than it should.

To me the most likly problem is gonna be your IAC. If all else fails, a radiator flush and fill could help if you are actually over heating.

 

[eugenesxyby999]

how can I test if the IAC is the problem before actually replacing it?

and also, when you said, "If you turn the AC on and the rpms fluctuate, or if your rpms surge, then fall but when you turn on the ac it doesn't do this." dont you mean, when I turn it off?

My rpms tend to drop sometimes without the use of A/C. and would slowly push itself back up to normal rpms. During the warmup period, if im standing behind the light, my idle is normal at 800 rpms, then it goes to like 650 and sounds like the engine is going to die, and then goes back to 800. so its usually never constant. rarely drops to 300 and i give it gas and it goes back up.

would this still mean its the IAC? is it an expensive fix? is the work hard for an average person?

and do I need the IAC valve or IAC motor?

how to test IAC?