Asked Aug 19, 2006, 06:02 PM
1. Ensure outdoor condenser unit is level in both directions.
2. Pour 8 parts water to 1 part bleach down the evaporator coil drain pipe 4 times per year, to prevent mold from developing.
3. Replace air filter monthly. This prevents dust buildup on the evaporator coils, which interferes with proper airflow and can cause icing problems.
4. Clean outdoor condenser coils in early April of each year with a garden hose. Remove front and side condenser coil covers and gently hose away dirt, grass, and debris. Straighten any bent fins with a fin comb. Don’t cut the grass around the condenser unit, while it is running.
5. Remove high voltage cover plate and clean area of dirt, fire ants, and spiders each year. Fire ants and spider webs are dielectric and can prevent the contactor from working. Examine wiring for burning and capacitors (on single phase current units) for leakage and swelling. In order to check condenser capacitance, all wires must be removed first. Spread fire ant chemicals around condenser unit to keep ants from globulating on the contactor. They are attracted to 60 Hz current. Spray connectors with WD-40, making sure not to get any on the contacts to the contactor.
6. Oil both condenser fan motor ports with 15 drops of ISO 32 (10 wt.) turbine oil each year. A 4 oz. Zoomspout Oiler from ACE Hardware costs $1.65. The finest synthetic lubricants, which I use, are Mobil SHC 624 and Amsoil RCH05.
7. Replace contactors (relay) proactively every 6 years. This is at the heart of properly maintaining an air conditioner and is the most overlooked preventive maintenance step. Some HVAC technicians will recommend replacing the whole outside condenser unit ($1,500), when only the contactor ($15) needs replacing. When contactor points open and close, they become pitted. As the cross-sectional area of the points gets cut in half, the resistance goes up by a square function (four fold). [Remember the formula for calculating the area of a circle = pi x r (squared)] This results in the compressor motor becoming starved for electricity, which causes it to work less efficiently and can burn it up. Method:
While the old contactor is still mounted, "crack loose" the four 5/16" hex-head bolts securing the main "line" and "load" wires. Using a 5/16" nut driver, remove the two hex-head mounting bolts to the old contactor, mount the new contactor, and then replace wire-for-wire from the old contactor to the new contactor. Use a pair of needle nose pliers and a small screwdriver to assist you in removing and replacing wires. Sit on a chair and take your time, while you perform this task.
In some areas of the country, HVAC supply houses won't sell to you, unless you work in the industry. It's a different story online. Here's what contactors look like: http://www.famousparts.com/cutham12pold.html
Click the contactor you are interested in; then, click the small picture you see to the right for the contactor's specifications.
Here is a very useful contactor cross-reference chart: http://www.white-rodgers.com/wrdhom/...pg_112_113.pdf
8. Replace digital thermostat alkaline batteries every 2 years. Low batteries can play havoc with the thermostat and cause dangerous inadvertent Locked Rotor Amperage that can damage contactors and compressor motors. Ensure your thermostat has an anti-short cycle feature, which can save your unit when the power goes off and then slams back on.
9. Obtain documentation on your air conditioner, while you can. Wiring diagrams and functional unit part lists are often in a plastic bag behind the high voltage cover to the condenser unit. It's invaluable data that will be destroyed by weather, if you don't get to it first. Keep the original in the house and replace a copy in the condenser unit. Record the data on the metal tag on the condenser unit--a lot of valuable data is even embedded in the model number;e.g. TTP036C100A2. Since there are 12,000 BTUs per ton, digits 5 and 6 tell us that this is a 3-ton unit.
10. Check system cooling. As long as the temperature differential between the air coming out of the air duct closest to the furnace and the air return duct is at least 15 degrees Fahrenheit, then the freon level is probably fine. An additional check is to feel the large, low pressure, insulated return line to the compressor--it should feel cool and have condensation on it.
11. Obtain a Fluke Model 16 HVAC digital multi-meter to check capacitors, temperatures, and other items. It also happens to be about the best DMM for diagnosing automotive electrical systems. A properly maintained air conditioner should last 25 to 30 years.
12. Wax your condenser unit, when you wax your car.
Turn the thermostat OFF, pull AC disconnect to condenser unit, and turn off furnace breaker (power to contactor coil) before performing any work. Use non-contact voltage meter to verify power is off. Finally, use a large plastic handle screwdriver between contactor and ground to confirm power is off.