Car stalls when A/C is on

[Foxbody93]

This forum has been great with helping me work the bugs out of my 93 Cobra, thanks all. But now I have one more. I didn’t notice this issue before because if I turn the A/C on while the car is standing it worked fine. However if I’m driving around town an pull up to a light the RPMs drop to around 500 then the car eventually stalls. I’m assuming the compressor is ok because there is no noise and it blows ice cold. I checked the timing with the SPOUT connector out and I’m good at 12 degrees 700RPM. I reinstalled the SPOUT connector and verified that the car is auto advancing the timing and it was, I think about 20 degrees may have been 18 either way it wasn’t 10. I ordered a code reader but it is traveling snail mail so I don’t have it yet. Any ideas?

 

[GreatWhite]

You can try pulling the codes to see if anything is coming up. The CEL works just as well as a code reader.

 

[Killer50stang]

This forum has been great with helping me work the bugs out of my 93 Cobra, thanks all. But now I have one more. I didn’t notice this issue before because if I turn the A/C on while the car is standing it worked fine. However if I’m driving around town an pull up to a light the RPMs drop to around 500 then the car eventually stalls. I’m assuming the compressor is ok because there is no noise and it blows ice cold. I checked the timing with the SPOUT connector out and I’m good at 12 degrees 700RPM. I reinstalled the SPOUT connector and verified that the car is auto advancing the timing and it was, I think about 20 degrees may have been 18 either way it wasn’t 10. I ordered a code reader but it is traveling snail mail so I don’t have it yet. Any ideas?

You could have a bad spot in the compressor, which would a pain to determine. Does it do it everytime the air is on or just once in a while?

 

[ninety15.0]

The AC puts a substantial load on the car. If the car is idling normally at 700 rpm thats perfect. The computer strategy actually calls for 675, so 700 is right there.

You could try cleaning out your IAC valve. perhaps its gummed up with carbon buildup. Does this happen even when the A/C is on LOW? what are the engine temps when this happens?

 

[monte87]

Just increase the idle with A/C on and car in gear. Problem be done. Its a simple fix, dont look to make it hard. Gotta love the EZ fixes. hahaha
Later Ant

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems. The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes] for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[Foxbody93]

You can try pulling the codes to see if anything is coming up. The CEL works just as well as a code reader.

I plugged the code reader in and performed both KOEO and KOER tests. In both cases the car was fault free.