Tips On Repairing Your Automotive Air Conditioner


The air conditioning in my old truck just wasn’t working the way it should. Just giving out warm air. A peek under the hood at the compressor revealed that it wasn’t running at all. A couple of things could cause this. Air conditioning compressors have an electric clutch built into them which, when it is released engages the compressor when you press the button for cooling. If the switch fails, the clutch will not release and the compressor will simply free wheel. If the clutch itself should fail it will not release and again the unit will simply free wheel. Either situation results in the same thing, no compressor action taking place and therefore no cool air in the cab.

Contrary to popular belief, refrigeration is not adding cold air to your immediate surroundings. It is actually the removing of heat from your immediate surroundings. A rather large difference. In your vehicle or home air conditioning system, the air that you perceive as cold, is actually the same air that was hot a few moments before…is has simply had the heat it contained absorbed. The absence of heat therefore, is cold.

Another problem could be a lack of refrigerant. The compressor may indeed run but there is no way for it to cool the cab as the required gas for the refrigeration process to work is absent. In the case of my truck, any fault in the system will result in a warning light flashing on the dash alerting me to a problem.

I had traced the problem down to a bad compressor. Some internal flaw had rendered it inoperative and I would need to replace it. A visit to a salvage yard yielded a fine looking replacement and I gathered the required tools and equipment to finish the job.

The compressor is driven by the serpentine belt so that was the first thing I had to remove to gain access. There are also two hoses attached to the unit. One is output and the other is input. A note of caution here. This is somewhat highly pressurized gas I was dealing with here. To be safe, I wear protective eye wear when releasing these hoses. And even then, I just crack the connection a little bit and allow the gas to escape instead of removing the connector immediately. And I avoid breathing the gas as it seeps out as well.

Once the hoses are off I remove any electrical connections and locate the proper sockets and remove the bolts holding the unit in place. Installation is straightforward. Put the bolts back in and torque to specification. Reattach the hoses, the electrical connections and the serpentine belt.

Re-charging the system is something you will want to let a competent shop do for you and here is why. The system has been open to the outside air. This means that moisture has gotten in. The system has to be connected to a vacuum pump and drawn down to a required degree of vacuum. The vacuum is a needed part of the way the system works and this pump action also serves to remove moisture. And then the refrigerant can be injected into the system to bring it up to it’s pre-break down capacity.

That said, if you simply wanted to re-charge the system because it was just low on refrigerant, this is something you can do yourself. Your auto parts dealer will have cans of pressurized refrigerant on hand and they have complete instructions on how to go about it. Again, wear eye protection. On you can easily purchase and compare all the material that you need in order to repair your air conditioner.