The easiest and most important preventive maintenance for your A/C system is to be sure that it is used on a regular basis. Running the system for five minutes each month (no matter what the season) will help ensure that the seals and all internal components remain lubricated.
Some newer vehicles automatically operate the A/C system compressor whenever the windshield defroster is activated. When running, the compressor lubricates the A/C system components; therefore, the A/C system would not need to be operated each month.
In order to prevent heater core freeze-up during A/C operation, it is necessary to maintain proper antifreeze protection. Use a hand-held coolant tester (hydrometer) to periodically check the condition of the antifreeze in your engine's cooling system.
Fig. A coolant tester can be used to determine the freezing and boiling levels of the coolant in your vehicle
Antifreeze should not be used longer than the manufacturer specifies.
For efficient operation of an air-conditioned vehicle's cooling system, the radiator cap should have a holding pressure that meets manufacturer's specifications. A cap that fails to hold these pressures should be replaced.
Fig. To ensure efficient cooling system operation, inspect the radiator cap gasket and seal
Any obstruction of or damage to the condenser configuration will restrict airflow that is essential to its efficient operation. It is, therefore, a good rule to keep this unit clean and in proper physical shape.
Bug screens that are mounted in front of the condenser (unless original equipment) are regarded as obstructions.
The condensation drain tube expels any water that accumulates on the bottom of the evaporator housing into the engine compartment. If this tube is obstructed, the air conditioning performance can be restricted and condensation buildup can spill over onto the floor of the vehicle.