Nissan, car stalls when ac is on

Maintenance/Repairs
1

The first time I turned on the AC this year, the car ran like normal for about 5 minutes. After that, I was coming to a stop light, I put the car in neutral, and it shut off. I could only get the car running again after I turned off the air. Then it would shutter very hard while idling. So far I have change the fuel filter and put cleaning stuff in the gas tank to clean the fuel injectors. When I tried running it again, it ran for about 10 minutes and stalled again. The car is a 1996 Nissan sentra. Check engine light doesn’t come on, and the car has had regular oil changes. There is 191,000 miles on it. Any help would be much appreciated.

2

Some Nissans back then had a two part, 6 pin TPS, throttle position sensor. It had two 3 pin connectors. One connector goes to a variable resistor, the other goes to a single pole, double throw switch which is used to detect foot off the gas pedal and WOT (wide open throttle). I suspect that the second part that detects when your foot if off the gas is not working. That could be from a dirty throttle body or a misadjusted throttle stop screw.

3

The problem might be caused from a dirty/defective Idle Air Control valve. http://www.rockauto.com/catalog/moreinfo.php?pk=816776&cc=1213131

The IAC valve controls the engine idle speed depending on the load imposed on the engine at idle. So when the AC is turned on and the compressor imposes a load on the engine, the IAC valve moves to a position to prevent the engine from idling rough or stalling when that load is imposed on the engine.

Tester

4

Not to disagree with tester, but if the TPS does not detect foot off throttle (closed throttle), then the computer will not send control signals to the IAC (idle air control). If the TPS checks out OK, then go to the IAC.

5

If there were a problem with the TPS, the Check Engine light would on with a code P0120-P0123.

Tester

6

Not if it is in the closed throttle/WOT position side of the switch.

7

The check engine light just came on today while I was testing the ac again.

8

I had the check engine light read, the code was P0505. It’s the IAC valve. I am going to try to clean it and the throttle body to see if that helps, if not I will have it replaced. Thanks for the help!