Car Parts and Accessories

Your car’s air conditioner consists of four basic parts: a belt- driven compressor powered by the car’s engine; an expansion valve; the evaporator; and the condenser. The entire system is sealed and contains pressurized refrigerant. Because the system is sealed, any repair work should be left to a professional. Do not, for example, even attempt to tighten or loosen any fittings. The refrigerant is extremely cold. When exposed to air, it instantly freezes anything it contacts, including your skin or eyes. Although refrigerant is normally nontoxic, the gas becomes very poisonous, even fatal, if ignited. You can, however, take steps to make sure your air conditioner is working properly or determine when to have it serviced. Operate the air conditioner about once a week (even in the winter) to keep the internal parts lubricated.

Step 8-1. Checking the refrigerant level on a system with a sight glass.

Locate the receiver/drier. It is a metal cylinder, something like a small fire extinguisher, usually located in the front near the condenser.

Step 8-2. Locating the sight glass.

The sight glass should be on top of the receiver/drier, but it might be in one of the metal lines going from the receiver/drier. The sight glass could have a protective cover made of heavy paper. If so, remove the cover. If not, wipe the sight clean with a rag or paper towel.

Step 8-3. Checking the air-conditioner clutch.

Start the engine, put the transmission in PARK, and set the parking brake. Listen to the engine and turn on the air conditioner. You should hear the clutch on the compressor engage and the engine speed change. If the clutch doesn‘t pull in and start the compressor, take the car for service.

Step 8-4. Reading the sight glass.

With the air conditioner running, look through the sight glass. If it is clear and cold air is coming from the vents inside the car, the system is fully charged. If the sight glass is clear but the air from the vents is not cold, the system is empty. Take the car for service. If you see bubbles (be sure the clutch is still engaged), the system is low on refrigerant. If the sight glass is foamy, the system is very low and should be checked by a professional.

Step 8-5. Checking the level on a system without a sight glass.

With the engine running and the air conditioner on, locate the receiver/drier. You should see two metal lines coming from the top of the receiver/drier; one going toward the front to the condenser, and the other line going toward the back to the expansion valve. Place one hand on each line and compare the temperatures. If both lines are about the same temperature, the system is probably fully charged. If the line going toward the front and the condenser is much colder than the other line, the system is probably low on refrigerant. Have the system checked.

Step 8-6. Checking the compressor belt.

Examine the compressor belt for any cracks, fraying, or glazing caused by the belt slipping. If the belt has any damage, install a new one. Now start the engine and run the air conditioner for a few minutes to warm up the belt. Turn off the air conditioner and shut off the engine.

Step 8-7. Checking belt tension.

Check the tension of the belt by applying pressure with your thumb midway between the two pulleys. The belt should deflect no more than 1/2 inch, less if the belt is new.

Step 8-8. Adjusting the compressor belt.

Examine the pulleys driven by the compressor belt. You should find one that has an adjustable slot. It could be the alternator pulley, an idler pulley, or the compressor pulley itself. If it is the compressor pulley, for example, use a wrench to loosen the mounting bolts. Place a pry bar (a hammer handle works fine) where you can use the leverage to shift the compressor out until the belt has the proper tension. Tighten the bolts while maintaining the tension on the belt. Remove the pry bar and recheck the belt’s tension. Check the tension again after driving the car with the air conditioner running.

Step 8-9. Cleaning the condenser.

Because the condenser is in front of the radiator, it tends to collect bugs, leaves, and other debris. If you have enough room between the condenser and the radiator, use a garden hose to run a soft stream of water through the back of the condenser toward the front. If you have enough room between the grill and the front of the condenser, use a soft-bristled brush to remove any debris from the front of the condenser. Be careful not to bend any of the soft cooling fins. Carefully straighten any bent fins with needle-nose pliers.

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