You can’t do everything; only a pro can check the coolant level. But you can easily handle most of the routine cleaning chores and save the extra $120 that it would cost to have a pro do them.
In this article, we’ll show you how to clean the outdoor unit (called the condenser) and the accessible parts of the indoor unit (called the evaporator). All the steps are simple and straightforward and will take you only a few hours total. You don’t need any special skills, tools or experience. If you aren’t familiar with air conditioners and furnaces/blowers, don’t worry. We’ll walk you through the basics. See “Parts of a CentralAir Conditioner,” below, to become familiar with how an air conditioner works and the parts of the system.
You may have a different type of central air conditioner than we show here—a heat pump system, for example, or a unit mounted horizontally in the attic. However, you can still carry out most maintenance procedures we show here, because each system will have a condenser outside and an evaporator inside. Use the owner’s manual for your particular model to help navigate around any differences from the one we show in our photos. And call in a pro every two or three years to check electrical parts and the coolant level.
Tip: Call for service before the first heat wave, when the pros become swamped with repair calls!
Figure A: Parts of a central air conditioner
The outside unit, called the condenser, contains a compressor, cooling fins and tubes and a fan. The fan sucks air through the fins and cools a special coolant, which the compressor then pumps into the house to the evaporator through a copper tube. The coolant chills the fins and tubes of the evaporator. Warm air drawn from the house by the blower passes through the evaporator and is cooled and blown through ducts to the rooms in the house. The evaporator dehumidifies the air as it cools it, and the resulting condensation drains off to a floor drain through a tube. The blower unit and ducting system vary considerably depending on whether you have a furnace (shown), a heat pump or some other arrangement. It may be located in the basement, garage, furnace room or attic.
Typical central air conditioner system
Your primary job here is to clean the condenser fins, which are fine metallic blades that surround the unit. They get dirty because a central fan sucks air through them, pulling in dust, dead leaves, dead grass and the worst culprit— floating “cotton” from cottonwood trees and dandelions. The debris blocks the airflow and reduces the unit’s cooling ability.
Always begin by shutting off the electrical power to the unit. Normally you’ll find a shutoff nearby. It may be a switch in a box, a pull lever or a fuse block that you pull out (Photo 1). Look for the “on-off” markings.
Vacuum the fins clean with a soft brush (Photo 2); they’re fragile and easily bent or crushed. On many units you’ll have to unscrew and lift off a metal box to get at them. Check your owner’s manual for directions and lift off the box carefully to avoid bumping the fins. Occasionally you’ll find fins that have been bent. You can buy a special set of fin combs (from an appliance parts store) to straighten them. Minor straightening can be done with a blunt dinner knife (Photo 3). If large areas of fins are crushed, have a pro straighten them during a routine service call.
Then unscrew the fan to gain access to the interior of the condenser. You can’t completely remove it because its wiring is connected to the unit. Depending on how much play the wires give you, you might need a helper to hold it while you vacuum debris from the inside. (Sometimes mice like to over-winter there!)
After you hose off the fins (Photo 5), check the fan motor for lubrication ports. Most newer motors have sealed bearings (ours did) and can’t be lubricated. Check your owner’s manual to be sure. If you find ports, add five drops of electric motor oil (from hardware stores or appliance parts stores). Don’t use penetrating oil or all-purpose oil. They’re not designed for long-term lubrication and can actually harm the bearings.
If you have an old air conditioner, you might have a belt-driven compressor in the bottom of the unit. Look for lubrication ports on this as well. The compressors on newer air conditioners are completely enclosed and won’t need lubrication.
1. If the power to your unit has been off for more than four hours:
- Move the switch from “cool” to “off” at your inside thermostat.
- Turn the power back on and let the unit sit for 24 hours. (The compressor has a heating element that warms the internal lubricant.)
- Switch the thermostat back to “cool.”
2. If you switched the unit off while the compressor was running:
- Wait at least five minutes before switching it back on. (The compressor needs to decompress before restarting.) With the air conditioner running, make sure it’s actually working by touching the coolant tubes (Photo 6). This is a crude test. Only a pro with proper instruments can tell if the coolant is at the level for peak efficiency. But keep a sharp eye out for dark drip marks on the bottom of the case and beneath the tube joints. This indicates an oil leak and a potential coolant leak as well. Call in a pro if you spot this problem. Don’t tighten a joint to try to stop a leak yourself. Overtightening can make the problem worse.
Begin by turning off the power to the furnace or blower. Usually you’ll find a simple toggle switch nearby in a metal box (Photo 7); otherwise turn the power off at the main panel. If you have trouble opening the blower unit or finding the filter, check your owner’s manual for help. The manual will also list the filter type, but if it’s your first time, take the old one with you when buying a new one to make sure you get the right size. Be sure to keep the power to the blower off whenever you remove the filter. Otherwise you’ll blow dust into the evaporator fins.
The manual will also tell you where to find the oil ports on the blower, if it has any. The blower compartments on newer furnaces and heat pumps are so tight that you often can’t lubricate the blower without removing it. If that’s the case, have a pro do it during a routine maintenance checkup.
The evaporator fins dehumidify the air as they cool it, so you’ll find a tube to drain the condensation. The water collects in a pan and drains out the side (Figure A). Most tubes are flexible plastic and are easy to pull off and clean (Photos 9 and 10). But if they’re rigid plastic, you’ll probably have to unscrew or cut off with a saw to check. Reglue rigid tubes using a coupling, or replace them with flexible plastic tubes.
Thank you for taking time to read some important and great knowledge and information.
Scott Myers, GRI
Century 21 Scott Myers, Realtors
11830 Wurzbach Rd. (The Elms)
San Antonio, Tx. 78230
Phone # 210-479-1222
Fax # 210-479-1981
Toll free Phone # 1-888-868-1222
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