Operation CHARM: Car repair manuals for everyone.

Exercising the A/C System

A/C units must be used periodically. Manufacturers caution that when the air conditioner is not used regularly, particularly during cold months, it should be turned on for a few minutes once every two or three weeks while the engine is running. This keeps the system in good operating condition.

Inspecting the system for effects of infrequent usage before the onset of summer is one of the most important aspects of A/C servicing.

First, clean out the condenser core, in all cases in front of the radiator. All obstructions, such as leaves, bugs and dirt, must be removed, as they will reduce heat transfer and impair the efficiency of the system. Make sure the space between the condenser and the radiator is also free of foreign matter.

Ensure evaporator water drain is open. The evaporator cools and dehumidifies the air before it enters the passenger compartment; there, the refrigerant is changed from a liquid to a vapor. As the core cools the air, moisture condenses on it but is prevented from collecting in the evaporator by the water drain.