How to Test an AC Compressor?

An air conditioner produces and circulates cool air (via a compressor and refrigerant). Your AC is critical for your comfort and health! When an air conditioner is not working effectively, it’s likely a problem with the compressor. Without a properly functioning compressor, your system will be inefficient and won’t cool your space effectively. So, how do you test an air conditioner’s compressor? How do you know if your AC’s compressor is working?

Signs Your AC’s Compressor Is Not Working

Some symptoms point to a poorly functioning compressor. 

• Reduced cooling: If your air conditioner takes longer than usual to cool your space or you notice it isn’t blowing cold air, there is likely something wrong with the compressor. 
• Unusual noises: If your AC emits strange noises (rattling, grinding, etc.), you probably have a compressor problem. 
• Water/oil leakage: Leakage around your AC indicates a faulty compressor. 
• How Do You Test An Air Conditioner Compressor?
• Purchase a multimeter (available at hardware stores). Set the dial to continuity.
• Turn off the power to the AC unit using the switch on the AC or the circuit breaker. 
• Let the unit cool down. Place your palm on the top of the AC to ensure it’s cooled. 
• Use a screwdriver to remove the unit’s faceplate (the part with ventilation holes).
• If your unit has an electric access panel, remove it to reveal the wiring. 
• Look for damage to the compressor (burnt or damaged terminals) or fraying wires.
• Find terminals R, C, and S (stands for run, common, and start).
• Place the pins of the multimeter onto the terminals of your AC. Place the red pin on the letter C and the black pin on the letter S. The device should read less than 30 ohms. A reading above this indicates a broken compressor. 
• Place the black pin on R and the red pin on C. This reading should also be under 30 ohms.
• Put the black pin on S and the red pin on R. The reading between these terminals should be under 30 ohms. If your readings are above 30, your compressor motor is likely faulty.

What To Do If Your Air Conditioner Compressor Is Damaged?

If you note damage to your compressor terminals, discover frayed wires or your multimeter readings are below 30 ohms, call a professional for service or maintenance. Repairing an AC compressor is complicated and best left to trained technicians. 

Is your air conditioner operating at less than peak efficiency? Having trouble with your AC compressor? Call McMillin Air.  We service all models/makes of air conditioners for a reasonable cost. Trust our licensed and insured technicians to help keep you cool!