In the cooling mode, if there is not enough air over the indoor coil, the coil temperature drops. When it drops below the freezing point, ice forms on the coil, which further reduces the airflow which in turn reduces the coil temperature. The compressor within the unit is a pump, which is designed to pump a vapor. As the airflow through the indoor coil drops, there isn’t enough heat being removed from the air passing over the coil to vaporize the liquid refrigerant inside the coil. Thus, instead of receiving a vapor, the compressor receives liquid refrigerant. This is called “liquid slugging”. The effect of “liquid slugging” is similar to the effect of pouring liquid into the cylinders of a gas engine. As liquids are not compressible, cylinder pressure exceeds the design limits, of the cylinder, and the valves, connecting rods, pistons, or other internal components are destroyed. The air conditioning unit starts out requiring that its filters be replaced. Now it needs a new compressor. Preventive maintenance or a new compressor, the better choice is clear.
In the heating mode, low airflow causes the heat exchanger to overheat. Heat exchangers are designed to operate at temperature between 120°F and 200°F. At higher temperatures, the heat exchanger oxidizes, its life-span is reduced, or it cracks and breaks. In either case, it makes far more sense to replace air filters on a regular basis.
A unit, designed to operate at ambient temperatures of 115°F or more, may stop operating at an outdoor temperature of 90°F. Due to the reduced heat transfer capability, the operating temperatures and pressures within the unit exceed the manufacturer’s safe limit and the unit shuts down. If the unit does not exceed the manufacturer’s limits by enough to shut down, it will continue to run at reduced capacity and efficiency, and at an increased rate of wear and energy consumption due to the increased work load. Condenser coil cleaning is included in our preventive maintenance programs.
Once again, if we exceed the design limitations of the device, or its anticipated life span, additional damage is caused. Much more cost effective to replace a relay or contactor during a preventive maintenance when compared with a motor or compressor replacement.
The second type of failure is when there is an insufficient refrigerant charge to cool the motor windings in the compressor. If the refrigerant charge is not sufficient, the motor within the compressor will overheat and burn up. A preventive maintenance program would spot this condition before it becomes a costly repair.
Low humidity can damage wooden objects like furniture, hardwood floors, musical instruments, as the dry air sucks out the moisture contained within them.
One of the most annoying effects of dry indoor air is static shock. As you walk across a carpet or slide off upholstered furniture, a static charge builds up in your body and results in a sudden, uncomfortable “zap” of electricity when you touch a piece of metal or other conductor.