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ABS light comes on, A/C goes out on 96 Tahoe

This happens randomly. The ABS light will turn on and the Air Condition goes out. No A/C and no fan. Then the ABS light will go out and the A/C comes back on. I can’t reproduce this. My mechanic can’t find the problem.
1996 Tahoe with 70K miles.

You are playing a joke on us, right??

The two systems are only connected electrically and maybe communicate on the CANbus. One shouldn’t have any effect on the other, in theory. I’ll give this some thought and return. Maybe someone else here has heard or seen this problem.

The daily stumper!

Edit: OK, did a search and found this isn’t all that uncommon and the ignition switch is often the culprit on GM vehicles. Apparently they are less than a $100 for the switch alone.

I expect Mustangman is on the mark here, but if that doesn’t pan out, I was guessing that the stability control system might be involved. It could possibly detect a fault somewhere & decide for safety reasons to turn the abs system off (which would turn the abs dash light on) and turn the AC system off. For example maybe the engine load due to the AC system might prevent some safety function from working properly. You’d think something like would would spawn diagnostic code(s) either in the engine module, the abs module, or the body module. Have all those modules been checked for diagnostic codes?

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Mustangman, the ignition switch is an interesting solution. Thanks for that.

George, the mechanic worked on this problem multiple times so I would say the diagnostic codes were checked.

The mechanic said something about the software in the ABS module having a problem and it was reloaded or reprogrammed but this didn’t help my situation. I can’t give a clearer description of what he said because sometimes I have a hard time understanding him.

I think George’s suggestion has some merit as well. I have experienced wonky sensors a time or 2 with stability control that pulled power or applied brakes at the wrong time… But your truck only has ABS, not stability control. You might consider pulling the ABS fuse for a test to see if it still acts up.

I guarantee you a 1996 Tahoe doesn’t have electronic stability control

it has ABS, and no more

On this vehicle, problems with the ABS system will not disable the AC

Mustangman was right on about the ignition switch. I also talked to a GM guy and he thought the same thing. My mechanic replaced it about 3 weeks ago. I’ve been driving it as much as possible and it’s been fine. Now my alternator failed. I think this is my third one. It’s been replaced and all is good. Hang in there old girl.

What brand alternators are you using . . . ?

I think my mechanic was putting in no-names. Now it is an AC Delco.