Listed below are some of the more common items that need repair in an air conditioning system. Please review each item to learn more about the causes and effects of each potential malfunction.
Fuses The Fuses and circuit breakers in the electrical supply to your air conditioning system have large demands. Their purpose is to prevent excessive load on the supply circuit, which could overload the entire system.
Fuses can fail from age, a loose connection, an electrical storm, a faulty electrical component in the unit, or from simply being loose in their holder. Typically, a faulty fuse will result in no operation at all or only the indoor circulating fan working.
Relays are electrically controlled switches that turn the motors, or other components of the system, on and off. There are a variety of relays in any given system and the thermostat operates most of them. The largest relay is called the contactor, and it controls the power to the compressor. These devices can fail when the contact surfaces stop making contact, become stuck in the on position, or they turn on the wrong component. Also, each time one of these switches turns on and off, the contact surfaces pit from electrical arching, eventually causing wear and tear.
A Capacitor helps your air conditioning systems’ motor start from a stand still and run efficiently. Capacitors are filled with an oil-like fluid that acts like an insulator. Capacitors can weaken over time decreasing the motors efficiency. Heat can also cause them to swell, leak and fail. On occasion, a capacitor’s circuitry will open, and will need to be replaced. A weakening capacitor usually has no noticeable effect on your system’s operation, however it could be causing the motor to run warmer than normal, shortening its life expectancy. Once a capacitor has failed, the motor will not run.
A Defrost Control limits the amount of ice that can form on you air conditioning system. An electric heat pump heats the home by extracting heat from the outdoor air. To do this, the system must operate at very cold temperatures. By operating at these temperatures, the outdoor unit can build up ice, decreasing its ability to heat. A defrost control will turn off the outdoor fan and place the system into a type of cooling mode to melt the ice. A faulty defrost control in the heating mode can prevent the system from going into the heat mode or allow excessive ice to build upon the unit, resulting in poor performance. A failure in the cooling mode can prevent the outdoor fan from running, resulting in a loss of cooling.
A Gas Valve is found in a gas furnace. When a signal is received from the thermostat, the gas valve controls the amount of gas needed for heating. A gas valve can fail from electrical or mechanical reasons. Debris or moisture in the gas piping can cause a valve to stick in the on or off position. A gas valve can fail at any time, but most fail after sitting idle over the summer. Normally a gas valve failure will result in no heat.
Furnace Circuit Board
A Furnace Circuit Board performs a variety of functions, from normal operation of the furnace, to the monitoring of the furnace’s safety circuits. The furnace circuit board can fail for a variety of reasons. The normal vibration of the system can weaken the solder joints in its circuitry, causing a failure. A short, or electrical failure, of the components connected to the module can damage the internal circuitry. Also, if it becomes exposed to moisture or excessive dirt, the circuitry can become damaged.
The failure of a furnace circuit board can have multiple effects, ranging from the indoor fan not turning on in the cooling mode, or a complete loss of heat.
Outdoor Fan Motor
The Outdoor Fan Motor, also referred to as the Condenser Fan, draws air through the air conditioning unit to cool it off. Often, this motor can be viewed from the top of the outdoor unit and has a propeller type fan blade and discharges air out of the top of the unit. Due to their location, these motors are subject to year round weather conditions, in addition to all of the indoor heat removed while cooling a home.
An outdoor fan can fail from wear and tear. Because they are running every time the outdoor unit is in operation, these motors can accumulate between one and two thousand hours of operation a year. Also, the harsh desert conditions subject the motors to extreme heat, weakening its electrical components.
In the early stages of failure an outdoor fan motor in the cooling mode may work through the night and morning hours but overheat and stop in the afternoon heat. This can result in the rest of the system overheating and stopping for several hours. Once the motor fails completely, the unit will no longer function. Continued running with a faulty outdoor fan motor can stress the system and eventually cause a compressor failure, and a much more costly repair.
Indoor Fan Motor
The Indoor Fan Motor, or Blower Motor, circulates the air from the home through the heating and cooling system. These motors run constantly when the unit is heating or cooling, but can also be set to run even when the air conditioning unit is off.
An indoor fan motor can fail from normal wear and tear, or from electrical problems. If dust collects in the motor, it can cause hot spots on the electrical windings and damage them. If dust forms on the fan wheel, it may cause the wheel to spin out of balance. The more out of balance a blower wheel is, the more stress it places on the motor bearings. Early signs of motor failure due to the bearings will be increased operating sound. Total failure of the motor will result in no heating or cooling. The system may try and work, but it will not be able to circulate air from the home. If left to run in this state for too long, other heating and cooling components can be strained or compromised.
The Compressor acts as a pump to circulate refrigerant through the air conditioning system. It resides in the outdoor unit, and like the engine of a car, has an audible sound when in use. Compressors can fail for a variety of reasons, including the motor bearings simply wearing out. Most times, a compressor will be strained by the failure of another component, such as a fan motor or the capacitor. Electrical storms can cause problems for a compressor, and almost always produce a noticeable increase in compressor replacements. Early signs of compressor failure may be a decrease in performance or an increase in operating sound. Total failure will result in no cooling, or no heating from a heat pump.
Refrigerant Metering Device
The Refrigerant Metering Device controls the flow of refrigerant through the air conditioning system much like a traffic light controls the flow of traffic down a street. All air conditioning systems will have at least one refrigerant metering device, and heat pumps will have two. Much of a system’s efficiency is derived from the proper operation of this device. Too little refrigerant flow will cause the system to have reduced performance, and could cause the compressor to overheat. Too much refrigerant circulating though the system could overwhelm the compressor, causing damage. Often, a total failure of this component will result in the system not cooling or heating at all.
Reversing Valves are only found on electric heat pumps and are used to reverse the flow of refrigerant from the cooling mode to the heating mode and back again. They reside in the outdoor unit, and all of the system’s refrigerant flows through them.
The failure of a reversing valve can cause the system to stick in the heating or cooling mode. At times, the valve may fail in an intermediate position resulting in the system not working.
Any debris in the system can cause the reversing valve to fail. Also, normal wear of other components in the refrigerant system, or the failure of a compressor or other device, can cause the reversing valve to fail.
A Restriction, or blockage, in the refrigerant system of a air conditioning unit can come in varying degrees. Screens, strainers or filters in the refrigerant system are installed in an effort to trap debris and prevent the failure of various components. However, large amounts of debris can result in a restriction, reducing the refrigerant flow through the system. A slight restriction may result in decreased performance. A larger restriction can result in the system not cooling or heating at all.
An Indoor Coil is a heat transfer device. The indoor coil absorbs the heat from the home’s indoor air, and passes it to the system’s refrigerant, which is then pumped outside. As the air passes across the coil, any airborne dust or lint that collects on the coil reduces its ability to perform. Also, to provide the highest level of heat transfer, the metal used is extremely thin. Airborne chemicals, detergents and cleaners can start corrosion, resulting in leaks. A coil in need of cleaning may have lower performance, or can ice up from the low airflow. A leaking indoor coil may operate for weeks, or even months, depending on the leak rate, but should be repaired or replaced to prevent further, more costly, damage. Leaks can occur in such locations that an attempted repair is not practical, and the entire unit may need to be replaced.
An Outdoor Coil is a heat transfer device. The outdoor coil draws the outdoor air across the coil to absorb the heat from the refrigerant. An outdoor coil should be cleaned periodically. Any dirt and dust in the air can be trapped on the coil and restrict its airflow and reduce its performance. They can also develop leaks from the constant vibration of the compressor, weakening the solder joints and tubing. The refrigerant is under very high pressures in the outdoor coil and even the smallest leak can result in a complete loss of the refrigerant charge. Any dirt and debris in the coil can increase these pressures straining the coil’s integrity.
Drain Lines allow your air conditioning system to drain off the water it has condensed from the air. Over time the drain line can become blocked and cause the drain pan in the unit to overflow. Dust and dirt from the indoor coil can be washed into the drain line, where it settles and causes blockage. Unlike the failure of most other items in the system, a drain line failure can result in expensive water damage repairs.