Residential Preventive Maintenace

Residential AC Maintenace
Basic maintenace for a household
AC should be done every 3 months that the AC unit is being used. This includes replacing the air filter, checking the fans and belts, clearing the drain line and making sure the area around the condenser is clear.

AC Maintenace Details

Air Filter
Turn the power off to the furnace, and look for the filter access panel. The air filter can be internal or external to the furnace. Look at where the return air duct meets the furnace and look for a long narrow opening or access. If the filter is internal, than remove the fan access door, normally below the burner access panel.

Throwaway filters should be changed every three months or more often if required. When you change the filter, if it appears to be very dirty, or the dust and dirt are falling off like a rain shower then change the filter more often. If you do not maintain your filter your evaporator coil will begin to look like this one to the left, which is completely plugged.

Because the coil is located inside the ducting it is very difficult and expensive to clean properly, keeping it clean in the first place is much easier.

Plugged Evaporator Coil

Evaporator Drain
The evaporator drain should have a trap big enough to stop water from being sucked into the unit and the trap should be removable for cleaning. Remove the trap and clean it at least once a year. This will prevent water from overflowing onto the furnace and fan. The picture to the left shows an evaporator drain that has not worked properly for years. Causing damage to the structure, and reduces the air quality. The mould and the slim that are growing here and being blown through out the building by the furnace fan. The damage to the coil and casing cannot be properly repaired and the unit needs to be replaced.

Electrical
Turn the power off to the outdoor condensing unit- There should be a service disconnect switch directly beside the equipment. Remove the access cover to the electrical compartment and have a look at the components. There should be at a minimum, a compressor contactor and a capacitor inside. Check for any signs of overheating on the wires, contactors or terminal. Overheated or lose connections will shorten the life of the compressor. Some pitting on the contactor is acceptable, but if they point appear charred or burnt right off or if the brass on the contactor discoloured. Replace the contactor if necessary, a faulty contactor can easily damage compressor, which would have to be replaced.

Burnt Compressor Contactor

Fan
Fan The fan compartment is the lowest panel on an up-flow furnace and the highest panel behind the vent connector on a down-flow. Turn the power of to the furnace at the service switch, if you cannot locate a service switch, turn the breaker off or remove the fuses before removing the panel. If the fan is belt driven, then check the pulley and belt for wear. Feel the inside groove of the motor pulley for ridges. The walls of the pulley should feel smooth, without raised ridges. If the fan belt is has been slipping, if will quickly wear down the pulley and reduce the fan speed. This can cause the coil to freeze and damage the compressor. Remove the fan belt, and check the bearings on the motor and blower. They should rotate freely, and quietly If it has a grinding sound to it or feels tight then new bearing or motor will be need. On direct drive motors the bearing wear can be heard when the fan is running. Replace any dried or cracked fan belts. When adjusting the fan belt do not over tighten the belt. It should be just tight enough not to slip, if it is too tight, it will damage the bearing. Too loose and it will slip and squeal. If you are replacing the belt, recheck the tension after 24 hours. New belts can loosen after the first few hours of operation.

On both belt drive and direct drive fans, check the condition of the fan blades. The fan on the right has been running without a proper filter. This will sharply reduce the airflow. Remove the fan to from the furnace for proper cleaning. If it can't be removed, then clean the fan in place by using a vacuum and a small brush. Be careful not to damage the balancing clips on the fan blades else you will need to buy a new fan wheel. After the airflow as been return to normal, there will likely be loose dirt blown out of the ductwork when you turn the fan back on. The increased airflow will pick up dirt from the supply air ductwork and discharge it out the supply grills. A good ducting cleaning company can help prevent this and they should be able to clean the evaporator and the fan as well.