Any automotive air conditioning repair system employs four basic parts-a mechanical compressor, driven by the vehicle's engine; an expansion valve, which is a restriction the compressor pumps against; and two heat exchangers, the evaporator and the condenser. In addition, there is the refrigerant that flows through this system. If the system is low on the refrigerant ( R134a for automotive use) than the system will blow hot air. In most cases the vehicles system can be recharged. Check for leaks before recharging.
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