It’s miserable!  It’s hot outside, you’re in traffic, the air conditioner isn’t working and you’re sweating your tail off.  Well, before you take your car to the repair shop, there are some things you can check yourself, starting with the cabin air filter.  If it looks like this, replace it with one that looks like this.  If you can’t circulate air into the cabin, you’re not going to be cool.

If it’s clogged up with dirt and debris, like this one that we took out of a car-you can see with this light up here, as we move it down-you can see the light actually disappears because it’s clogged with crud from the road.  Well, that can be cleaned with a garden hose and some engine cleaner.  And lots of times that’s all it needs.

All right, what’s next?  Well, the next thing is moving air, and that means you need to look at the cooling fan on the car.  Most cars have electric cooling fans so when the air conditioning is on, the cooling fan should be running.  If it isn’t, you need to check the cooling fan relay.  That’s usually mounted someplace very near the fan, and most of them are exposed to the weather, and the things you’re looking for are burnt connectors and corrosion inside the connectors.  And if you have the equipment, you may have to check the relay itself.

Well, another thing that goes along with that is right here. If your car happens to use a mechanical fan, this is a fan clutch.  This should engage when the engine is hot and there’s hot air coming through the radiator.  You rev the engine a little bit and the fan that’s attached to this should rev with the engine.  If it continues to coast, perform a full test on it.

Then another thing you can look at is the compressor.  The belt is turning with the engine.  When the compressor is on, or when the air conditioning is on, the center part of the compressor should be turning with the belt.  If it isn’t, well, you go over and you locate the pressure switch.  You check the pressure switch, especially the connection again for corrosion.  Unplug it, reconnect it.  Lots of times that’ll take care of it.  If it doesn’t, well you probably need a professional.

Then one thing you don’t do, you don’t head to the parts store and buy one of these kits and start dumping refrigerant into it because too much refrigerant can be worse than not enough.  It can actually damage parts.

And one thing is for sure, you can’t diagnose an air conditioning system with one gauge.  It takes two and the comparison between two readings.  So, better off to leave that sort of thing to the professional.


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The address is MotorWeek, Owings Mills, MD, 21117.