GM Air Conditioning Parts

Diagnose a Bad AC: an Easy DIY for GM Vehicles

There's nothing worse than to be on the road in the heat of a North Carolina summer and have the air conditioner go out. After all, it doesn't just cool the interior during a drive. It also keeps the seats, armrests, and steering wheel comfortable enough to the touch not to burn you when you get in for a drive.

The thing is, when car AC systems do fail, the cause could be anything -- the compressor, condenser, the evaporator, refrigerant levels, even just a weakened seal or a degraded or broken hose. Here's how to tell what the problem might be.

Low Refrigerant

Your Buick Enclave, for instance, doesn't cool properly, and usually, the cause is low refrigerant -- either levels are a problem, or there's a leak. You can figure out which.

Start your engine, set the AC to max cool, set the fans on their highest setting, and listen for the compressor clutch to click on. If it seems like it's working too fast, refrigerant's likely low. If it's not due for service, a leak's likely. What you want to do is check all the seals -- the fittings, the compressor hose manifolds, the hoses themselves (at the fittings), the front seal and O-rings (these seal the compressor's pressure switches), the Schrader valves, and where condensation drains out the evaporator. Also, check the condenser for pinholes. Replace whatever you need to.

AC Compressor Failure

Interior of, say, your Cadillac XT5 warmer than usual? You can chalk that up to compressor problems, most of the time. Weird noises from it, the clutch getting stuck -- these make it pretty much official. How to tell if you've got a bad clutch is simple: connect a voltmeter. No voltage, the clutch is likely failed. Other issues could be a faulty cycling switch, a blown fuse, or low refrigerant pressure. Replace whatever's not working.

Faulty AC Condenser

An SUV like Chevy Traverse or GMC Acadia, you might also run into things like frost accumulation, with a flashing AC button and a lit HVAC warning light to boot. You might even notice discharge pressure issues. These almost always mean condenser trouble.

Here's how to tell. Start the engine, max out the AC, put the fans on high, and check the air coming through the vents. If it's not that cool, the condenser's likely to blame. (Of course, if no air's moving at all, the blower motor is likely bad.) You'll want to check the cooling fans on the condenser and radiator to make sure they're working, and look for any dirt or debris clogging the airflow in the condenser area -- specifically, the condenser vents to the outside. Also, check the cabin air filter for clogs. Again, replace any problem parts.

Of course, if you're not sure what to do, a GM dealer or an authorized GM service center would be glad to help.

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