How to Troubleshoot a Car Air Conditioner

If your car's air conditioner isn't properly working, you don't have to drive off to a mechanic. Follow these steps first to see if you can troubleshoot the problem and fix it.

Difficulty: Challenging

Instructions

1. Look for leaks in the system. You may have lost refrigerant in the air conditioner due to a leaky compressor or O-ring seal. There may be a leak in the air conditioner hose. Before you recharge the refrigerant, identify the leak and repair it.

2. Attach air conditioner service gauges to determine if the cooling system has adequate pressure. Even if there is adequate refrigerant in the system, low pressure causes problems.

3. Determine if the compressor's magnetic clutch is engaging. This may be a mechanical problem with the clutch, or it may not work because the refrigerant is low. If the clutch works but doesn't turn the compressor, the air conditioner compressor needs replacement.

4. Check for blown fuses. Also, check the wiring. Fixing a blown fuse may only be a temporary fix if you can't resolve the underlying problem.

5. Measure the temperature of the air in the car. If the air conditioner blows cold air for just a little bit, the system has moisture in it and is freezing up.

6. Listen for excessive noise. It's usually the compressor, but it could also be a hose or belt that needs replacement.

[g8trgrl2002]

on 5/9/2009 the advice is great but what if the ac worked just fine one day and the next day it started blowing out burning hot air.....

[Mark6221]

on 8/22/2008 All good advise, but what if the AC works just fine at highway speeds but won't cool at all at lower rpms? Compressor is working fine, belts are good, no leaks in the system, cools good on rainy days.....how do you determine if its a faulty pressure regulator?

[WOODY20012]

on 3/30/2008 THESE ANSWERS ARE ALL GOOD BUT
CHECKING THE SYSTEN FOR LEAKS . YOU WILL NEED A BLACK LIGHT OR A ELECTRONIC LEAK FINDER UNLESS YOU SEE WET OIL AT A JOINT OR BLOWN HOSES (IN 29 YEARS OF AUTH SERVICE NOT A VERY COMMON THING)
ATTACH A/C GAUGES THE MANIFOLDS ARE NOT CHEAP AND YOU WILL NEED TO KNOW WHAT THEY MEAN AND THE RELATIONSHIP WITH THE OUTSIDE TEMP
THE A.C COMPRESSOR NOT A CHAP GUESS AND IF YOU REPLACE IT YOU WILL STILL NEED TO TAKE IT TO A SHOP TO HAVE A EVACUATION AND RECHARGE (CAN'T JUST RECHARGE )YES CHECK THE A/C OR HVAC FUSE IF BLOWN FIND OUT WHY . NEWER VEHICLES HAVE HVAC COMPUTER MODULES . IF A SYSTEM HAS MOISTURE IN IT YOU WILL NEED TO FIND OUT WHY R HAVE A EVACUATION DONE AND A RECIEVER DRYER (ACCUMULATOR ) REPLACED.
A KNOCK NOISE MAY MEAN THE COMPRESSOR IS COMING APART AND YOU WILL HEV METAL I THE SYSTEM . THEN A COMPRESSOR WITH CLUTCH (YOU MAY NOT HAVE THE TOOLS TO RE