It's easy for modern condensers to become internally clogged with debris, reducing cooling performance. Condensers adopted a more efficient design when A/C systems switched from R-12 refrigerant to R134a. These newer condensers are more likely to fail, due to their multi-path configuration. If you have a failed compressor and find metal contamination in your system, it is highly recommended that you also replace your condenser.
If a condenser is found to be defective, replace it along with the expansion valve or orifice tube and the accumulator/dryer. Flushing the A/C system can help clean blockages by dislodging sludge and debris and purging it from the system. After flushing, put the system into a vacuum for approximately 20 minutes to boil out any moisture. Then recharge the system with the factory-specified amount of refrigerant. Any oil that was lost should be re-added during the recharge process. Check the A/C system's operation and performance.
Common A/C Terms and Diagnoses
Inspect the compressor, clutch, and surrounding areas for signs of oil and dirt. The clutch can sling oil onto surrounding areas if there is a leak.
Inspect the hoses for oily spots.
Evaporator drain oily
Look for oil near the evaporator drain.
If your vehicle is equipped with an electric cooling fan, verify that the fan runs continually when the engine is on and the A/C compressor is engaged.
Check the front of the engine-fan clutch for a buildup of grease on the thermostatic coil. This is an indicator that the fan clutch may be defective.
Is the compressor coming on?
Verify that none of the fuses are blown. If the fuses are good, check for 12 volts and a good ground at the compressor. If the proper voltage and ground are present and the compressor still won’t come, on suspect a compressor-coil problem.
All A/C systems have some method to keep the evaporator from freezing up. These include a thermostatic switch (cycles the clutch when the evaporator temperature falls to a set point, usually just below 32 degrees), a pressure-cycling switch (usually mounts on the accumulator/dryer and cycles the compressor when the suction pressure drops to approximately 25 psi), and a variable-displacement compressor (changes its displacement in order to control evaporator temperature).
As you can see, diagnostics are an important first step in A/C-system servicing. Correctly diagnosing your problem early on will save you time and money in the long haul. Good luck, and stay cool.