Troubleshoot the air conditioning system in your 1994 Chevy before summer hits. Whether it is a problem with the magnetic clutch or AC compressor, the issues are relatively simple to diagnose. Before taking your Chevy to a mechanic for what could turn out to be an expensive repair, you can run through a few troubleshooting steps on your own.
Turn on the electric blower fan and AC (with the engine running) to check the controls for any damage. If the controls are resistant or loose, have them replaced. If the fan does not turn on, this could indicate a blown fuse, or the fan itself could have malfunctioned.
Check the fuse box for any blown fuses. Consult the owner's manual to locate the fuse box for your particular model of '94 Chevy. Read the instructions on the fuse box to identify the fuse connected to the AC system. If the thin metal fuse wire is broken, replace the fuse with another of the exact same rating.
Start the vehicle, and check the two heater hoses under the hood that protrude from the firewall. The hoses are roughly the thickness of a regular garden hose. The firewall is the metal partition dividing the engine compartment and passenger compartment. It runs from just beneath the windshield to the underside of the engine. Place your hand on the two heater hoses. They should both be warm to the touch. However, one should be noticeably cooler than the other. If it is not, the valve control may need to be replaced.
Turn the AC up to the highest setting with the engine running. Check under the hood to see if the magnetic clutch connected to the AC compressor turns on. If the clutch does not engage, the system could be low on refrigerant. Have a mechanic refill the system. A noisy compressor could mean that it is close to failing.
Inspect all the AC hoses for any leaks. If you notice a green, oily residue on the hoses, they may need to be replaced.
Use the AC pressure test gauge with the engine off to check for adequate pressure. Remove the black caps from the service ports on the '94 Chevy's AC unit. Screw the blue hose to the low-side service port and the red hose to the high-side port. Check the readings on the red and blue pressure monitors. A normal pressure reading should be between 50 and 80 psi. If the reading is not in this range, there may be a leak in the system.
