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How to repair an air conditioning compressor

How to repair an air conditioning compressor

Keeping an air conditioner compressor well maintained and fixing any issues in it increases the efficiency of the unit and prolongs its life. An air conditioner compressor functions using a motor with ignition and operating coils. The motor spins a piston that compresses the system's refrigerant. Due to the high-pressure load that the piston creates during ignition, the engine uses the ignition coil to reach maximum speed. The amperage load that an air conditioning compressor uses through its ignition phase burns the terminals of the loose wires. A faulty capacitor increases amperage consumption during the compressor start-up and operation phases.

One of the most common problems homeowner’s report are for malfunctioning air conditioners. While there are numerous reasons behind this problem, one of the most common problems that an air conditioning unit faces is a faulty compressor. In this article, we have prepared for you a step by step approach to help you understand how you can fix some basic problems with an air conditioning compressor.

Tips to Repair Basic Air Conditioning Compressor Issues

  • Turn off the condensing unit and switch of the air conditioner system. It is normally located on the electrical panel, next to the house’s electricity meter, and is labeled "Air Conditioner," "A / C" or "Heat Pump."
  • With the right screwdriver, open the electrical panel of the condensing unit and the compressor cover. The panel is located on the side of the condensing unit, where the cables enter the unit. If the unit's fan is mounted on the compressor cover, remove the screws securing the cover and turn it to the side of the unit. The fan uses long cables that allow access to the compressor without disconnecting the cables from the fan relay.
  • Inspect the compressor’s capacitor located on the electrical board of the capacitor. The capacitor is like an oval or round metal cylinder with cable lugs coming out of its cover. If the capacitor has an enlarged lid or if it is leaking, replace it with exactly the same model. The replacement capacitor must have the same capacitance and voltage. Else it can cause serious damages as soon as you turn on the system.
  • Pull the wires from the compressor’s capacitor cable terminals, using a pair of pliers to grip the cable connectors. Observe the capacitor contactor cable that is connected to the capacitor terminal with the "Com" label and the compressor cable that connects to the "Herm" terminal of the capacitor.
  • Place the multi-meter to measure capacitance. Hold a multimeter lead in each capacitor terminal and compare its reading with the capacitance of the capacitor, as indicated on the capacitor’s identification tag. The multimeter reading should remain within 10 percent of the capacitor's reading. If not, you must replace it. Replace the capacitor cables in their respective slots in the capacitor.
  • Insert a screwdriver into the small slot on the side of the compressor cable terminal cover. Remove the compressor cover with the screwdriver.
  • Inspect the cable connectors connected to the terminals of the compressor cables. If the latter look burned or are not properly tied to the terminals, replace the connectors with a compressor terminal repair kit. Follow the instructions in the kit, paying special attention to cable splices. Replace the compressor terminal cover.
  • Replace the condenser compressor cover. Tighten the cover fixing screws with the appropriate screwdriver.
  • Place the multi-meter to measure amperage. Fix the multimeter's amperage probe with a clamp to the black wire that leads to the common terminal of the compressor.
  • Look for the "LRA" and "RLA" ratings on the condenser on the identification tag. The LRA (Locked Rotor Amperage) gives the maximum capacitor ignition amperage. The RLA (Rated Load Amperage) indicates the operating amperage of the condenser equipment.
  • Turn on the condenser switch and observe the reading of the multimeter. This reading should approximate the LRA of the capacitor. Once the compressor reaches the maximum speed, the multimeter reading should fall to the RLA of the capacitor. Turn off the condenser switch. If the initial reading of the multi-meter exceeds the LRA of the condenser, follow the instructions to install a capacitor for strong starts through the terminals of the compressor operation capacitor. If the latter does not solve the high value of the LRA, it replaces the compressor. If the compressor gives a high RLA reading, check the system's refrigerant level to see if it is high. If it gives a low reading, check the system's refrigerant level to see if it is low.


Above are just a few problems and solutions for the failure of an air conditioner compressor. Professionals in high-voltage air conditioning systems in your locality will perform multiple tests to determine the exact cause of the failure. If the root cause of the problem is not addressed, it is likely that the old system will fail even when you install a new compressor. Replacing a compressor in an old system is rarely profitable. The cost of replacing a compressor is 50% or more of the cost of installing a new one. If you have no warranty, replace the entire unit, not just the compressor.

If the problem seems more severe than it is recommended not to try a DIY. You can end up damaging your air conditioning unit beyond repair. It is better to look for the services of a professional HVAC repair and maintenance service near you. While sometimes it might just be a basic issue other times the system might have some serious issues. You can end up exposing yourself to refrigerants, which can be hazardous for your health. So, instead of experimenting and risking both your health and money, just give Comfy Climate a call and let us handle all your HVAC related issues at the most reasonable rates offering the best quality of services!


In the United States, only technicians certified by the Environmental Protection Agency (EPA) can legally check refrigerant pressures.

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