How to Decide whether to Repair or Replace a Compressor

November 15, 2014

Commercial HVAC Unit, Graves Heating and Air, Rosa Media Productions

Commercial HVAC Unit Main Switch

Generally compressors are not the point of failure in a system. Many times the failure point is the electrical power and controls supporting the compressor. A compressor may not run, but doesn’t mean it is bad. It could also be burnt wires or a capacitor. These repairs are fairly inexpensive from the part point of view. The labor will be the expensive part of those repairs.

A compressor can be bad in 3 ways:

  1. The motor could be grounded or have open windings. It pops the circuit breaker instantly. The tech will need to check this with an ohmmeter.
  2. It could also be internal overload. This is a device that shuts down the compressor when it is running at high a temperature. This could indicate a low level of Freon or a dirty condenser. Not enough oil in the system can cause more friction, this could also result in an overheated compressor.
  3. A compressor could be a non-pumper – high suction, low discharge.

If a technician is telling you that your compressor is bad, you want to know exactly why. They need to do a pressure test. For instance:

If it is running 250/125 psi, that shows that something is mechanically broken inside the compressor.

If it is 300/20 psi, any tech should know that that is an expansion valve not a compressor.

Compressors get changed out all the time when the problem is not the compressor. It is some other aspect of the unit. Technicians really need to write down pressures if they are saying it’s a bad compressor, either not pumping or worn out.

If the compressor is still running, then you need a solid and specific diagnosis of the problem. If it is not running, then it has to be an open winding, its grounded, has a locked rotor, or it’s simply not bad. If it is not one of the above, it is probably a burnt wire or a capacitor, again, a much cheaper repair. A compressor not running has distinct causes, and the technician should be able to specify the problem in writing.

If your AC needs repair or service, please call us at 562-944-2118 to set up an appointment.

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Important Reason NOT to Close AC Ducts for more Efficiency

June 15, 2014 1 Comment

AC vent

Closing too many AC vents can damage your compressor

Closing registers or supply vents is recommended by some as a way to save on energy costs. Unfortunately, this idea can actually backfire on homeowners if they close down too many vents.

AC systems are designed with a certain amount of air flow in mind. When a user closes vents, it reduces the amount of air flowing through the system. If too little air flows through the ducts and over the evaporator coil, the refrigerant fails to heat up and evaporate into its gas state properly. The amount of airflow is critical to boil the refrigerant from a liquid to a gas. It has to absorb enough heat out of the house in order to change into a gas.

If the refrigerant stays in liquid form and gets into the compressor, it can cause serious damage to the compressor. Replacing a compressor is usually an expensive repair.

Poor airflow can also result from a dirty filter. See our tip on changing your filter here.

If your AC needs repair or service, please call us at 562-944-2118 to set up an appointment.

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