Very often it's good to leave the repair of your car's air conditioning to the professionals, as adding refrigerant or replacing certain hoses is best done with the right tools and expertise. However, you can often at least diagnose some problems you might be having with your car's air conditioning; even if you can't fix them yourself, you can help the technician pinpoint the problem so that he or she knows where to start looking. Consider a few quick tips on how to diagnose your own car air conditioning problems.
1. Low refrigerant
Refrigerant in a car's air conditioning does often leak out through tiny holes in the hoses and connectors, and this can be more common in older cars as those connectors pull away and come loose and as hoses tend to break down and develop larger gaps and breaks. You might be able to see drops of refrigerant on your garage floor after your car has been sitting for some time, but a good way to test for a leak is to add a special dye to the car's air conditioner system. You can buy this dye at any auto parts store and add it to the condenser of the air conditioner. If the dye should drip out under your car, then you know that the refrigerant is dripping as well.
2. Cool but not cold air
If your car gets cool but not quite cold enough when the air conditioner comes on, it may be the condenser that is not working. Turn on the car and then turn on the air conditioner to full blast and note if the condenser comes on. This is the part that runs air over the refrigerant coils so that it gets cold before it's pushed into the cabin of the car, and you should hear it humming or making a slight pumping sound.
If you only notice that the fan to the air conditioning unit comes on, then the unit is not getting cool air to push through to the cab of the car and is just working as a fan alone. You can look for any blockage in the condenser such as leaves, bugs, and the like and give it a good cleaning. If this doesn't cause it to start working, a technician can see if it needs replacing or if there is too much pressure in the system that is causing it to switch off.