Tune Up Your Air Conditioner
February 13, 2007
Summer is almost upon us and and as we all know, that means hot weather. To help keep your cool this summer, it might not be a bad idea to consider servicing the old 'swamp cooler' or air conditioner, depending on which system you have. In addition to avoiding heat prostration, a properly maintained system operating in an efficient manner can help you save on those always unwelcome electric utility bills. This month we outline basic service and maintenance procedures that you can do yourself.
The predominant cooling machine in New Mexico is the evaporative cooler, or "swamp cooler." The energy expended to provide adequate cooling by this means is much lower than the energy used by refrigerant based air conditioners because a small water pump is used instead of a refrigerant compressor. The evaporative cooler works well in the dry New Mexico climate.
To get the most from your cooler, it must have through and regular servicing and maintenance. This can be a do-it -yourself job for most of us. Just follow these simple steps:
1. Inspect the blower fan belt. If it is worn, replace it with a belt that has the same number stamped on it as the one being replaced. Adjust the belt by loosening the screw that fixes the motor position. The tension should allow 1/2" to 3/4" deflection of the belt when you push on the center of the span with your thumb.
2. If the cooler pads are dirty, or have mineral deposits caked on them, replace them. They could be cleaned, but replacement cost is so low that new pads are recommended. Measure the opening in the frame and get that size. A pad that is a little oversized is okay, if the store is out of the correct size. You can squeeze it into the frame. Do not get a pad that is too small or the cooler won't work well.
3. Clean the water pan, which is the bottom of the cooler housing. Dirt in this area will eventually go through the pump, plug the water passages, and cake on the pads. In addition, the pump should be protected with a screen to minimize this problem.
4. Adjust the water level to be at least an inch above the pump inlet. Loosen the set screw and adjust the float arm, Bending the metal arm can also do the job.
5. Check the water supply piping and overflow piping for breaks or leaks due to winter freezing. Water must flow freely through these tubes. Turn on the "pump only" switch and clean debris from clogged lines with a wire. You can also disconnect the tube from the pump and blow out debris by attaching it to a small diameter garden hose. If this tubing is cracked or permanently clogged, inexpensive replacement parts are readily available.
6. If the pump is not putting out a strong flow, you must replace this inexpensive part. Connect the wires with wire nuts and electrical tape. Be certain that no wiring is in contact with water. When doing any electrical repairs, always remove the fuse, turn of the house power, or turn off the circuit breaker for the cooler.
7. Oil the fan bearings at the oil cups with 5 to 10 drops of lightweight machine oil. Rotate the shaft to assure even distribution. Be sure the rotation is smooth. If hard rough spots exists, the bearings need replacing. If the motor has oil cups, oil it also.
8. A large amount of air moves through the cooler, and any wind-blown debris, such as cottonwood tree cotton, will be sucked into the pads. You may have to hose this debris out of the pads during the summer to keep your cooler in top form.
9. Inspect the bottom of the cooler for signs of rust. There are several types of rust preventative available at minimal cost which can greatly extend the life of a cooler.
Your cooler will now be working as well as it can. Most evaporative coolers are operated by a manual switch. We usually turn on the unit when heat buildup becomes noticeable, typically in the early afternoon. Once overheating occurs it is difficult to cool down the mass of the house and its contents. You can install a thermostat or timer to activate cooling as required. This will help keep the building from overheating and keep you cool during the hot summer months.
REFRIGERATED AIR CONDITIONING
Refrigerated Air Conditioning is most common in areas that are humid. Although control of indoor temperature is more precise and introduction of outside air with associated pollen is minimized, evaporative cooling can produce the same amount of cooling for one-seventh the cost of electricity than refrigerated air-conditioning.
You will be able to achieve a reduction in energy usage by proper maintenance and servicing of your system. The following actions are recommended:
1. Examine the fan belts that drive fans on the condenser and house air mover. If they are frayed or worn, replace them. Adjust the tension to allow 1/2" to 3/4" depression with moderate force. Do not over tighten, as that would injure the shaft bearings. If your installation has an adjustable pulley on the air mover, be sure the belt is on the smallest diameter to mover the maximum amount of air.
2. Clean or replace the house fan filter at least monthly. A plugged filter will retard the flow of cold air.
3. Clean the coils with a commercial coil cleaner. This product is available at refrigeration supply houses and can be applied with a garden insecticide sprayer. Follow the suppliers instructions.
4. Straighten all of the evaporator and condenser coil fins with a small pointed stick or a special plastic fin comb. Bent fins do not allow proper air distribution.
5. Oil all motor and shaft bearings with 5 to 10 drops of lightweight machine oil applied in the oil holes near the shaft supports. Rotate the shaft to assure that the oil is distributed over the shaft. Be sure the rotation is smooth. If hard rough spots exist, the bearings need replacement.
6. If the condenser is at ground level, be sure no vegetation or foreign material is restricting the air flow path. If possible, shade the condenser with trees or bushes, which will improve the cooling efficiency by elimination of direct sunshine.
7. Be sure the suction or cool line from the condenser to the compressor is insulated with snap-on urethane or other high R-value insulation.
8. Measure the temperature difference between the warm return air entering the evaporator coil and the coil discharge air into the house with two thermometers. The temperature difference should be a minimum of 12 F to 16 F for satisfactory efficiency, with even higher temperatures preferred. If this test shows a low temperature difference, have a serviceman check the refrigerant. The system may need recharging, or perhaps the compressor is malfunctioning.
If have performed all of these checks, there is little more than you can do. Your only hope now to reduce your energy bills is try to reduce the heat load on the building and raise the thermostat as high as comfort allows. Keep your windows closed. This is the reverse of the evaporative cooler requirement. Open the windows at night to let the cool night air do the job.
Finally, don't cool the house when no one is home. If your schedule is predictable, a timer can activate the air conditioning just before you arrive. Turn up the thermostat if you are planning to be home.
Special thanks to the New Mexico Energy and Natural Resources Department for the information contained in this article.