HOW TO DIAGNOSE YOUR CAR’S AC PROBLEMS
If the air conditioning is set to max cool and fans on high, but is only blowing moderately cool air:
- Check to see that the cooling fans on the condenser or radiator are running when the air conditioning is on.
- Look for any restrictions like leaves, bugs or dirt that would keep air from passing over the condenser.
- Check the cabin air filter to ensure that it is not clogged.
Check the pressures in the system using a manifold gauge set. The recommended high-side and low-side pressures can be found in the repair manual.
2-START WITH THE AC COMPRESSOR
When diagnosing an air conditioning issue, it's easiest to begin at the compressor:
- With the engine running turn the A/C on max cool, set fans high, and make sure that the clutch is engaging on the compressor.Note: this is not the pulley, but the center piece that engages the pulley to the compressor shaft. If the clutch is engaging and disengaging rapidly, the refrigerant may be low.
- If the clutch is not engaging, use a voltmeter to check for voltage getting to the compressor.
- If there is voltage - the clutch may be bad.
If there is no voltage - a cycling switch may be bad, a fuse may be blown, and the system may not have enough refrigerant pressure to trip the low pressure cutoff switch that cycles the compressor.
3-MOST PROBLEMS ARE CAUSED BY LEAKS
Leaks are the most common problem associated with the air conditioning system.
If pressure is low, then there may be a leak:
- Using a UV A/C leak detection kit is the easiest way to find a leak. Follow the instructions on the packaging to introduce UV dye to the system and UV light to find the leak.
- Check around all fittings to verify that they are all secure.
- Check hose manifolds on the compressor.
- Check the front seal and the o-rings sealing the pressure switches on the back of some compressors.
- Check where the hoses are crimped onto the fittings.
- Check the Schrader Valves.
- Check for pin holes in the condenser.
- Check where the evaporator drains condensation with UV light. Sometimes oil or dye can be seen.
Note: The dye check will not work if the system is too low and the compressor is not cycling.