2001 coupe, all stock, no mods.
Problem is the engine will die with the A/C compressor coming on.
Doesn't always do it. but it will do it with the car driving or sittting still.
It always starts right back up.
When driving, if it quits, I push in the clutch, and start it. Let the clutch out, and it goes.
If I don't touch the A/C button, it stays running and I have air conditioning, for hours........
But IF I TURN IT ON AFTER the engine starts, it kills the engine. and it kills the engine every time the compressor comes on.

Here's the scenario:
car starts up and runs absolutely fine. I can drive it for hours.
But, when I select the Air conditioning, the engine will die.

I have a friend that has a Tahoe that was in a wreck, and he bought it back from the insurance company for parts.
He has the engine sitting on a stand, so I have been able to borrow parts as long as I return them.
To date:
I swapped out:
the idle air control valve,
The fuel pressure regulator,
MAF,
Throttle body,
Alternator,
Crank trigger sensor.
Throttle position sensor,
Pulled off the air filter to check for obstructions,
I checked voltage on the fuel pump fuse while running and then when it quits and the fuse is still powered.
I put a scanner on it, and no codes, The DIC confirms it.
pulled the cover off the fuse box, removed and replaced the fuses and relays to make sure there were no loose contacts and let the car run with the wiring exposed in the fuse boxes, and I don't seem to be losing any power anywhere on the fuse boxes.
I even used his engine computer to start it and run it in the garage, and the A/C still shuts off the engine.
The only thing I touch is the ignition switch and push in the clutch.
But why does it kill the engine AFTER the engine is running, but not if selected before engine start?
Sometimes it will kill the engine if the A/C is selected prior to start, but rarely.
What is going on???? Where am I losing electrical power?

 

Well,,,,,,,,,, If your sure you have NO Mods or PCM TUNING, here are my thoughts:

Obtain a set of AC gages and check the High and Low pressures of the compressor. If the high pressure is high out of spec, it could cause an idle issue.

Is the compressor making any strange noises?

Examine everything that can effect the IDLE quality of the engine:

- Vacuum lines broken, damaged, loose , missing
- Dirty MAF
- Leak between the MAF and the Throttle Body.

The HVAC provides an AC ON signal to the PCM. Does the engine respond to the AC ON signal when you turn the AC compressor ON????? The signal increases the Idle and adds air and timing to the engine



Bill

 

Well Bill,
it isn't just idle. I can be on the freeway, air conditioning working just fine, nice sunny day, the inside of the car is bone chilling cold. cruising along about 1750 RPM, cruise control on, not a care in the world, and the steering gets hard to turn, the gas pedal does nothng, and the car is decelerating. Radio is still blaring,the HVAC fans are still blowing, gauges are working, tach is dropping, oil pressure is up, HUD is illuminated, gas gauge is working, everything is powered except the engine.

I push in the clutch, turn the key, and it starts right back up again, and i continue on my merry way for maybe 20 minutes, when the same thing happens.

outside air temp about 110 degrees F, 10% humidity, and the coolant temp is indicating about 90* over ambient where it always is unless it is below 90*F.
On the freeway, maybe 10 degrees cooler, depending on if it is a hill or downgrade.

It just started doing it on it's own.
The air conditioning hasn't been touched since I got the car 6 years ago, and it's cold cold cold. Besides, high pressure switch would have cut out the compressor, and starting it immediately would see elevated pressures for a little bit till the freon cooled down.
I checked vacuum lines and all the connectors I could find, especially the ones under the engine covers.
But thanks for weighing in on this.

 

Well,,,,,, the only thing that you havent replaced or touched is the IGNITION SWITCH. The engine sounds just like someone turned it OFF.

Take a look at this post and see if you can overhaul the switch:

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

BC

 

Sounds to me like the A/C creates a big enough voltage drop (famous ground problem) that offsets the mosfet ground reference in the ignition coils or their trigger point.

 

I will give the ignition switch a try. Let you know what happens.
i will check more into the coils after the ignition switch.
One complicated thing at a time!

 

I didn't say the coils were suspect.

I think you have a ground issue.

 

Well, it's not the ignition switch. after that exercise, it still did it. Borrowed a scanner, and the Mass air sensor was the culprit.
Changed it and now the thing runs without quitting.
gave an input low code, and impending fail code for the mass air sensor.
When I swapped it out for the tahoe mass ar, it ran funny, and did not want to acelerate smoothly. So I put my old one back on.
With the correct part number mass air, it is fine.