QuestionQUESTION: My 2000 Hyundai Sonata AC was working fine. I parked the car and came back a few minutes later and it no longer blew cold air. What could have happened?
ANSWER: Hi Kim, sorry it took so long to get back with you. When you start driving, does your A/C sometimes get back cold or doesnt blow cold air at all?
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QUESTION: Not at all.
AnswerOk Kim, well lets see. Realize that auto AC is basically a refrigerator in a weird layout. It's designed to move heat from one place (the inside of your car) to some other place (the outdoors). This should give you a start on figuring out what the problem might be and either fixing it yourself or talking intelligently to someone you can pay to fix it.
Become familiar with the major components to auto air conditioning:
1.The compressor, which compresses and circulates the refrigerant in the system
2.The refrigerant, (on modern cars, usually a substance called R-134a older cars have r-12 freon which is becoming increasingly more expensive and hard to find, and also requires a license to handle) which carries the heat
3.The condenser, which changes the phase of the refrigerant and expels heat removed from the car
4.The expansion valve (or orifice tube in some vehicles), which is somewhat of a nozzle and functions to similtaneously drop the pressure of the refrigerant liquid, meter its flow, and atomize it
5.The evaporator, which transfers heat to the refrigerant from the air blown across it, cooling your car
6.The receiver/dryer, which functions as a filter for the refrigerant/oil, removing moisture and other contaminants
Check to see if all the R-134a leaks out (meaning there's nothing in the loop to carry away heat). Leaks are easy to spot but not easy to fix without pulling things apart. Most auto-supply stores carry a fluorescent dye that can be added to the system to check for leaks, and it will have instructions for use on the can. If there's a bad enough leak, the system will have no pressure in it at all. Find one of the valve-stem-looking things and CAREFULLY (eye protection recommended) poke a pen in there to try to valve off pressure, and if there IS none, that's the problem.
Make sure the compressor is turning. Start the car, turn on the AC and look under the hood. The AC compressor is generally a pumplike thing off to one side with large rubber and steel hoses going to it. It will not have a filler cap on it, but will often have one or two things that look like the valve stems on a bike tire. The pulley on the front of the compressor exists as an outer pulley and an inner hub which turns when an electric clutch is engaged. If the AC is on and the blower is on, but the center of the pulley is not turning, then the compressor's clutch is not engaging. This could be a bad fuse, a wiring problem, a broken AC switch in your dash, or the system could be low on refrigerant (most systems have a low-pressure safety cutout that will disable the compressor if there isn't enough refrigerant in the system).
