Crazy idle problem with a/c

[philly5eagle]

Been every where looking for an answer for over a year and have not found one yet. Hopefully someone can help. 1990 eclipse awd m/t. Started having a problem last year with the idle when the a/c is turned on. The idle should come up 200 rpms to compensate for the a/c load. It no longer does. Instead, it will drop to around 500 rpm and sound terrible. Tried disconnecting the a/c belt and then turning it on, b/c the idle should then bump up 200 rpm which would tell me if the compressor is putting to much of a load on, but rpms don't move. Also, the a/c cooling fan that is in behind the radiator is not coming on also. I unplugged it and found the plug was fried?? Cut the end off and put another end on and it still doesn't work. Replaced the a/c controller that is under the dash and nothing. The a/c does blow cold though, but idles like crap. Checked the isc per the required test for ohms and it tests normal.
I have read in multiple places about some people having the same problem and after replacing the isc, the ecu, a/c controller, compressor, t/b, battery, and alternator they are still having the same problem. There has to be something else. If I can ever get it fixed, I will post it everywhere b/c I have found a lot of people with the same problem. Some have been so frustrated they just sold the car. I did notice the problem after my alternator went last year, but I'm not sure what would have happened. What is strange is that so many others have had the same thing. Everyone first points to the isc, but when that is not it then what?

 

[boosted_91_tsi]

I am in the same boat as you. I just picked up a rebuilt ISC in hopes it will cure it. It will be a while before I find out because I need a tranny rebuild and have all of the intake off. By the time I get her running again, it will be winter.

 

[philly5eagle]

It's funny b/c I keep finding people with the same problem but we can't get a solution. I keep posting b/c I know someone will find an answer.

 

[will90Eclipse]

My car does the same thing, when your driving its o.k. but when I get to a stop sign the car just dies. I've learned to live without A/C and just roll the windows down

 

[grnchevyz]

Could it be as simple as a relay? If your fan plug was fried...I assume you meant burnt or melted....lead me to believe an overload or a short.

I'd backwards check the wires from the "fried" plug. Sometimes the simplest idea is the solution.

I a little new to the DSM engine, maybe I'm way off to left field, but it seems a logical place to start...and an inexpensive one

 

[patty AT forge]

If you mechanically disconnect the AC but the RPMS are still low it seems that it would have to be an electrical issue.
I'm more familiar with Toyotas so forgive my ignorance but do the DSMs have a seperate AC idle up valve?
Check voltage with the AC on and off...
Also try turning your idle up in 100 rpm increments and see if the problem goes away.
Disconnect the blower motor and see what happens.

 

[LewGervais]

You have described my problem to the "T". I have a 1996 GST and I have the same idling problem when I use my A/C. I find it hard to live without my A/C this time of the year cause I live in central Florida.

I was told the problem is the IAC (idle speed controller) a small electronic gismo on the Throttle body that is suppose to raise the idle when we turn on the A/C. That part cost over 300 dollars from the dealer. I just found a rebuilt one on Ebay for about 139 dollars. Has anyone ever tried changing this part and have it fix their idling problem?