AC on = almost stall condition....Why is this? HELP
Thread Starter
Burning Brakes
Joined: Apr 2001
Posts: 992
Likes: 0
From: Atlanta GA
AC on = almost stall condition....Why is this? HELP
I start my car it's fine I teun the AC on and it drops and dang near stalls..then will surge and then it will level out after few minutes of running...I have struggled with this for 2 years and still can't figure it out...I don't understand why my car does this..I want to be aable to just start it and turn the AC on with no issues.....Any help on this would be great.... :confused:
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: AC on = almost stall condition....Why is this? HELP (apollo30346)
When you turn on the a/c a voltage signal is sent to the ECM (12 volts - Manual Air; 7 volts if Electronic). Verify the voltage signal with a scanner or at ECM Pin B8. The signal increases IAC counts or air flow through the throttle body to maintain idle for compressor load. You can see this on a scanner and injector pulse width will increase too. If no signal, dash controller is faulty or wire is open to the ECM. If the signal is present at ECM, but idle counts don't increase, ECM may be bad. If the signal is present and IAC counts increase, cleaning the throttle body & IAC pintle should cure the problem though you may need to replace the IAC. In either case, be sure to reset the IAC & minimal idle which is outlined in tech tips.
Thread Starter
Burning Brakes
Joined: Apr 2001
Posts: 992
Likes: 0
From: Atlanta GA
Re: AC on = almost stall condition....Why is this? HELP (SunCr)
Have not done a volt test, but I did not know how until you discribed...the ECM is a month old and I have a new IAC, but was not sure how to install...I was unsure what I needed to do to reset and set and stuff...Still fuzzy on that...I cleaned the TB ....I wish I had a scanner to do this test....If you you could walk me through the change on the IAC and the reset process...That would be great...Where can I get a scanner from and how much is one for my 88 model car?
Thanks for the help BIG TIME....I have been fighting this for 2 years and have had no luck....Maybe with your help I will get it...
Thanks for the help BIG TIME....I have been fighting this for 2 years and have had no luck....Maybe with your help I will get it...
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: AC on = almost stall condition....Why is this? HELP (apollo30346)
Auto Xray makes a decent unit and is available at most Discounters. You only need an OBD 1 compatible model which should be the cheapest. To set minimum air, warm up the engine and verify that TPS voltage is .54 & that base timing is at 6, then ground the Diagnostic Link by connecting a paper clip between the A & B Terminals and turn the ignition on (don't start the car). Disconnect the IAC harness. Disconnect the timing connector. Start the car. Engine will barely idle, but should run. Using the adjustment screw on the throttle body, set idle between 400 & 450 rpms. Turn off the engine & reconnect the timing wire. Reset TPS voltage at .54. Slightly depress the accelerator and start the motor. Run it for 5 seconds and turn it off for 10 seconds. Restart and the idle should be ok. Procedure is a great deal easier with a scanner. Common IAC counts for idle without a/c is 9 - 15. Expect 20 or a few more the a/c on. If everything is right, idle and throttle tipin will be smooth without any hesitation whatsoever. If you still have the a/c problem after all this, possibility exists that your compressor is headed south and overwelming ECM control - though usually if this is the case, you would also feel it at cruise as the system cycles on and off.
[Modified by SunCr, 5:06 PM 7/29/2003]
[Modified by SunCr, 5:06 PM 7/29/2003]
