Air Conditioning Repair Guide

Air Conditioning Repair Tools

When it’s hot and your Air Conditioner stops pumping out cold air you can be scrambling to find the first available AC repair company to fix your AC system.  You have to sweat it out for hours or sometimes days before they arrive.  When they do get there you are hit with an expensive repair bill.  The good news is that most repairs are easy.  If you are mechanically inclined then most air conditioning repairs are easily done.

Common Air Conditioner Problems

When your AC stops blowing cold air you can usually get a good idea what is wrong by turning on your system and observing the unit while it is running.  You will need to assess what part of the system is causing the problem.  Below is a list of common failure points for a given symptom.

Air Conditioner Will Not Turn On

  • Power Failure
  • Defective Contacts
  • Bad Capacitor
  • Loose Terminals
  • Compressor Overloaded
  • Refrigerant Low
  • Thermostat

Compressor Runs But Condenser Fan Will Not Start

  • Loose Terminals
  • Bad Capacitor – Run Cap
  • Bad Condenser Fan Motor

Compressor Runs Continuously – No Cooling

  • Refrigerant Low
  • Bad Compressor Valve
  • Restricted Evaporator Coils
  • Dirty Air Filter
  • Restriction in Duct work
  • Thermostat

Compressor Runs Continuously – Cooling

  • Thermostat
  • Excessive Load
  • Defective Contacts

Compressor Is Noisy

  • Bad Run Capacitor
  • Loose Bolts
  • Bad Compressor

Water Leaking From AC Unit

  • Bad Drain Pan
  • Blocked Drain Pipe

Air Conditioning Repair List

Once you have an idea of what part of the AC system is failing you can checkout common issues to see if they are the cause.

Power To Your Air Conditioner

Air Conditioner Power BoxBefore you start any type of air conditioning repair you should first remove power from the A/C system.  First open the gray box that is usually next to the air conditioner and pull the black handle out to cut the power.  Don’t for get to reinstall this when  you finished or your air conditioner may not turn on.  It is possible to install it upside down, so make sure to note how it was installed before you remove it.  If your A/C will not turn on and this piece is in correctly then check the circuit breaker panel going to the unit.  Power surges, faulty equipment, and loose wires can cause the AC circuit breaker to trip.

Contacts / Relay

Air Conditioner Electrical ContactorWhen the contacts close high power is applied to the air conditioner’s electrical system to start the compressor and condenser fan motor.  The high current that flows through them will cause the relay’s contacts to arc every time they open and close.  As the contacts age this arcing can cause the contacts to fail.  They can weld together causing the system to not shut off.  They can also fail to close due to shorts in the relay’s coil or loose wires.  If this happens your air conditioner will not turn on.  A lot of AC relays have a piece that can be pushed with a screwdriver that will force the contacts to close.  If they are closed manually the system should run.

Start and Run Capacitors

Start CapacitorThere are 2 different kinds of capacitors in your air conditioner.  First there are start capacitors.  These capacitors increase torque to the motor to get it to begin turning and come up to speed.  Second there are run capacitors which help with efficient operation of the motor when it is running at normal speed.  The capacitors will have markings on them that indicate their values.  When you replace one you should make sure that the replacement part has the same voltage and mF (micro Farad) rating as the original.  It is usually a good idea to short across the terminals of the capacitor with a metal object before handling it but only after power is removed.

Loose Terminals

Wiring At AC Control BoardElectrical connections can come loose over time.  Your air conditioning system has many different types of connections.  After removing power check to make sure they are not corroded and are firmly tightened.

Refrigerant Low

Refrigerant GaugesRefrigerant is responsible for transferring heat through the evaporator and condenser coils inside the system.  It also lubricates moving parts in the compressor.  Your air conditioner should never loose it’s refrigerant.  If it does than there is a leak in the system.  You can check your air conditioner’s charge with a set of A/C gauges like the ones in the picture.  Most air conditioners will have a chart inside the main panel which may need to be removed first.  The chart will say what the high and low side pressures should read.  The high and low side service ports are before and after the compressor.  They are different sized connections and only the blue hose will connect to the low side, and only the red hose will connect to the high side.  If you determine that your system is low on refrigerant it is best to call a qualified air conditioning repair company to service your unit and repair the leak.

Condenser Fan Motor

Condenser Fan MotorThis motor turns the condenser fan which removes heat from the refrigerant after it comes out of the compressor.  Once the refrigerant is cooled it goes through an expansion valve and is routed through the evaporator coil to provide cool air to your home.  If the motor doesn’t spin then the air conditioner will not be able to cool and may eventually overheat.

Compressor Bad Or Overloaded

Air Conditioning Units CompressorThe compressor is responsible for pressurizing and circulating refrigerant throughout the A/C system.  Most manufactures provide a 10 year warranty on the compressor and you should make sure that your compressor isn’t under warranty before doing any type of work to it.  The most common type of compressor is hermetically sealed with all of the operating components inside.  If your compressor is bad it is best to have a licensed air conditioning repair company replace or repair it.  The compressor may become noisy when the capacitor is marginal or bad or when it’s mounting bolts are loose.

Drain Issues

Air Conditioner DrainThe cold temperatures produced by your air conditioner during operation will cause moisture in the air to condense on the cold parts of the system.  The evaporator coil and lines drip water which is caught in the drain pan.  As the drain pan fills, a drain pipe routes the water away from your house.  When the drain becomes clogged water can flow into your house or other areas where it could cause damage.  In most cases the blockage can be cleared with a shop-vac or by disconnecting the drain line and flushing it with a garden hose.