During the hot summer months, your car's AC system has to work harder than ever to keep you cool. If the air conditioning system is having problems on a hundred degree day, then it can even threaten your health. This is why you should be prepared to be able to know how to diagnose certain problems with your car air conditioning system. Car air conditioning system problems come many different variations. These problems can be classified in any combination of 4 basic problems. The fan can either blow hard enough, or not. The fan can even be stuck in one speed or missing a speed. Another problem can be that the air does not come out of the right vents. Finally, there is the temperature of the air that comes out of the vents either being cold or not. Being able to identify the part of the system that is causing the problem is the first step on the way to fixing it. Here are a few troubleshooting tips for your vehicle's air conditioning system.
Fan problems
Since it is the fan’s job to move the air, the ducting part of the system that directs the air to the right vents is also crucial to air movement. One of the most common problems is that the fan works right, but there is hardly any air coming out of the vents. If this happens there is an obstruction in the system, check the cabin air filter that is in the back of the glove box on most cars.
If the fan is just not spinning fast enough to get proper air movement in the system, then there can be a problem with the fan motor resistor, or the fan speed switch, itself. Usually it is the resistor, which is normally in the dash behind the air conditioning control panel. You might notice it being a little bit melted in severe cases. If not, then you will need to consult the repair manual for your vehicle. If the fan is not blowing at all, you need to check it for power, and then trace back to where power is lost. Usually it is going to be the motor, if it does not spin at all.
Vent Problems
There is nothing more frustrating than the vents not working right. On some vehicles the vent systems have popular issues. There is an air mixing system that is used to regulate the air temperature, and there is a delivery system that determines the vents the air comes out of. If the air is not cold enough, but everything else is working properly, then you would look into the mixing system. There is a door in the air conditioning housing that moves back and forth between the heating and air conditioning coils that is used to mix the air.
At the same time, there are also different motors and doors for the different venting systems. These actuators wear out, and sometimes the door that they open can break. So if you are missing air from only a particular set of vents, look into where the mode door actuator is for the vent you are having problems with.
Refrigerant Problems
If your air conditioning system freezes up or stinks like mildew, then you have a refrigerant leak. Any leaks that happen must be fixed immediately, because if the system is continued to run, it can damage the compressor. One sign of a system that is low on refrigerant is the compressor will continually kick on and off every few seconds. If the compressor does not come on, and there is enough refrigerant in it, then check the low pressure switch that is usually screwed into a big fat silver air conditioning line. You can simply unplug it, and put a paper clip jumper between the terminals in the wiring harness, and the compressor will start, if that is the problem.
Things you need
It is always a good idea to have the repair manual for your vehicle handy simply because they are all different. Some air conditioning systems even have self diagnostic capabilities. Granted, usually these kind of vehicles have to be diagnosed at a repair shop, but there is almost always a way to pull diagnostic codes from the air conditioning system without the dealership style scan tool. Another good tool to have handy is a multi-meter, which you can get at almost any auto parts store for about twenty dollars. You should also have a small socket set with all of the tiny sizes, if you plan on having to go into the dash for anything. The final tool that you will need to accurately diagnose refrigerant system problems is a set of air conditioning manifold gauges. Sure, the universal bottle that you use comes with one that you can monitor “low side” pressure you still need to be able to monitor the “high side” pressures, in order to know if the compressor is doing its job properly.
You now have a general outline of directions you can go with almost any kind of air conditioning system problem that comes your way. If you need to know how to perform any of the skills needed to do any testing, you can get that out of a high quality repair manual for your vehicle, and it will be specific for your car. Besides that, the only other thing you need to have in your tool bag is good luck!
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