Maintain the air conditioning system in your Toyota Corolla All-Trac, to prevent small problems from turning into expensive repairs. Fortunately, diagnosing problems is a relatively simple process, whether you have an issue with leaking refrigerant or a blown fuse. Before taking your vehicle to a mechanic, run through a few basic troubleshooting steps on your own.
Start the engine and check the air conditioner dashboard controls for any looseness or resistance. Replace the dials, if necessary. Ensure that both the electric blower fan and the air conditioner are turned on.
Check all the air conditioner hoses for any damage or kinks. If you notice kinks in a hose, squeeze the hose between your thumb and forefinger until the kink is diminished. Look for any oily residue on the hoses or air conditioner components. If you notice oil or coolant, replace the hoses, as needed.
Set the air conditioner control to the coldest setting (with the engine running) and open the bonnet to check that the magnetic clutch (attached to the compressor) turns over. If it does not engage, the system may be low on refrigerant. Have a mechanic check the system for any leaks and refill it with refrigerant, as needed. Ensure that the drive belt is securely connected to the compressor. If the compressor is excessively noisy, you may need to replace it.
Inspect the fuse box (located on the left of the steering wheel) for any blown fuses. Check the schematic on the inside of the fuse panel for instructions on how to locate the fuse connected to the air conditioner system. If the metal strip inside the glass tube is broken in two, replace it with another fuse of the exact same amperage rating.
Open the bonnet (with the engine running) and locate the two hoses near the firewall. The hoses are roughly the thickness of a garden hose. They should both be warm to the touch. However, one hose should be noticeably cooler than the other. If it is not, the valve control may be defective. Have a qualified mechanic investigate this further for you.
Attach an air conditioner compression gauge test (with the engine turned off) to check for adequate pressure in the air conditioner system. Normally, the reading should be between 22.7 Kilogram Per Square Inch (PSI) and 80 PSI. If it is lower than this, have a mechanic investigate this for you because there may be a leak in the system. To connect the air conditioner gauge, attach the blue hose to the low-side service port, and the red hose to the high-side service port.