A/C causes car to stall...

PoisonDrop · Post by **PoisonDrop** » October 14th, 2005, 4:38 pm

Well after I got my BP put in, the idle was high (1500 all the time). When I turned the A/C on, it would drop to around 800 RPM.

So today, not thinking about the problem above, I adjusted my idle. I got it set just fine, and the car was running great, but then when I turned the A/C on, the car stalled out, probably since I didn't have that much RPM to play with. So I had to reset my idle to 1500 so I can run my A/C and DRIVE at the same time

.

I have searched extensively, but I can't find the problem. It's like the computer isn't compensating for the extra load of the compressor. I checked the wiring, and everything is hooked up and hooked up correctly. Any ideas what could be wrong?

Oh, and no air leaks or anything. The car runs great...just a huge RPM drop with the A/C on.

Thanks in advance!

azazel95 · Post by **azazel95** » October 14th, 2005, 5:58 pm

Lets see... I know you said you checked all the wire's connections...did you check the wire itself? Maybe crossing somewhere causing a short? If it doesn't stall immediately, is the AC maybe drawing to much power? I'm trying to think of any possible causes... so bear with me...

I would guess it has to do something with electrical, because I can't think of any reason the AC would cause a car to stall mechanically. Unless it was somehow blocking the air flow or something like that..? But you said all your hoses and connections are fine...

Any noises like whirling or buzzing?

Any codes?

Really these are just thoughts typed out and I'm not a mechanic (I know a decent amount) so sorry if I'm no help

PoisonDrop · Post by **PoisonDrop** » October 14th, 2005, 8:45 pm

I would agree that it is electrical. When the idle is high, it doesn't stall, but the RPM drops a lot. The RPM seems to cycle with the compressor clutch and the A/C fan, so I'm led to believe that the compressor is drawing too much of a load on the motor and the ECU isn't raising the RPM to compensate for the increased load. I can't figure out why though.

From the wiring diagram, it seems that the ECU controls the compressor clutch and fan, so if it can turn all of that on and off, it should know INTERNALLY whether or not to raise the RPM to compensate.

I'm kinda stuck here.

PoisonDrop · Post by **PoisonDrop** » October 14th, 2005, 10:15 pm

I was thinking...is it the idle control valve or something that the ECU controls that actually raises the RPM? Well whatever part does the job, could that be malfunctioning? I don't know how to test if it is raising the RPM for other types of loads on the motor...

ariesdude · Post by **ariesdude** » October 15th, 2005, 2:39 am

You probably already checked this - but just to make sure - have you checked the drive belt condition/tension - maybe if the belt is damaged or too tight - that might lead to an irregular load when the compressor turns on ...

PoisonDrop · Post by **PoisonDrop** » October 15th, 2005, 4:18 pm

Yeah the belts are good...brand new when I put the motor in about a month ago. The tention looks fine.

I just checked the diagnostics and she's throwing a code 34, which is the code for the ISC valve. So that would be my problem. I think one of the water lines that goes to that assembly was rusted, so maybe I got some rust and what not in there.

Maybe I'll just get a new throttle body, so if it is rust it won't happen again. Any other suggestions? The wiring is fine. I got the engine harness new so I'd know that the wiring was all OK.

PoisonDrop · Post by **PoisonDrop** » October 15th, 2005, 7:20 pm

Wow...I just looked up a new ISC valve from the parts store and it's like $400 USD! That's insane! I guess I'll try to find one at the junk yard that looks good. If I can't, then I guess I have to fork out some cash for a new one. I may just do that anyway, but it's kind of hard to do when I'm at the point of just HOPING it will fix my problem...

PoisonDrop · Post by **PoisonDrop** » November 14th, 2005, 5:43 pm

Just thought I should update for anyone else with the same problem...

I used the IAC valve from my old 1.6 SOHC and now everything works great. The part numbers are the same on both motors, so it just swapped right over. Didn't have to spend a cent!

nolig2278 · Post by **nolig2278** » August 24th, 2006, 10:35 pm

I know this is old post but I have same issue.
I will try to find a new idle control valve too. Did you ever find a good price or should i just look in yards.

What ecu r u using. I cant mine to light the check engine light so i can't pull codes.

thanks