Your car's air conditioning starts out nice and cool, but it gets warmer and warmer until you're left with nothing but hot air. So, what gives? Automotive A/C systems are complex, and there's rarely a straight answer for an ailing A/C system.
Think of the fuses in your vehicle as akin to the circuit breakers in your home. Each fuse is designed to sever the electrical link between specific systems and components if something goes wrong. Anytime your vehicle's electric system sends too much current to a particular component, the fuses break the connection by shorting out, thus preventing any damage from occurring.
An electrical problem caused by an A/C system component can cause a related fuse to short out, causing you to lose your A/C. Simply replacing the fuses will only cause the problem to return later on. You're better off having an experienced technician track down the underlying cause and make the appropriate repairs.
Compressor Clutch Problems
In some cases, your car's A/C system might not work because the compressor's electromagnetic clutch isn't engaging properly. The compressor clutch allows the compressor pulley to disengage and freewheel during times when cooling isn't needed so the compressor isn't forced to run endlessly.
A faulty compressor clutch may work at times, but if it fails in the middle of an air conditioning cycle, you'll quickly end up with warm air instead of the cool air you wanted from your A/C system.
Expansion Valve Problems
Most automotive A/C systems have a thermal expansion valve located somewhere between the evaporator and condenser. The expansion valve's primary job is to carefully meter the amount of refrigerant entering the evaporator.
If the expansion valve becomes clogged with debris, usually from metal particles created by an ailing compressor, the resulting blockage prevents the refrigerant from entering the evaporator. The blockage also causes the rest of the A/C system to deadlock, resulting in hot air.
Refrigerant leaks are a common cause of most automotive A/C issues. Any number of issues can lead to a leaky A/C system, including physical damage caused by a previous accident, aging O-rings and seals and corrosion caused by moisture contamination within the A/C system itself. Most refrigerant leaks are gradual enough for the average car owner to not notice until it's too late.
If you suspect your lack of cool air is due to a refrigerant leak, you can have your technician test the A/C system for leaks. Many refrigerants contain a special dye that's visible under UV light, making it easier for technicians to quickly pinpoint leaks.
Contact a company like Modern Auto Air for more information.