Specifications

Heartland Owners Forum http://manuals.heartlandowners.org
Heating and Cooling Guide V1.pdf Page | 12 Version: 1, March 15, 2013
Short-Cycling
When the air conditioner is shut off by any means (loss of power, thermostat cycled to OFF, or the
thermostat reaching the set point and turning it off) it should not be restarted for several minutes. This
is to allow the refrigerant gas to equalize and the compressor motor to cool down. (That is the hissing
sound you hear when the A/C shuts off).
If the motor tries to restart too soon, it can cause an over temperature condition. The motor has
internal thermal protection that will protect it and you may hear it try to start several times before it
succeeds. Most RV power protection systems will delay restoring power to your coach for two minutes,
specifically to protect you’re A/C motors. Some thermostats also have built-in short cycle protection.
Fan Operation
There are two motors in each air conditioner. One motor drives both the inside fan (evaporator) and the
outside fan (condenser). The other motor is inside the compressor and moves the refrigerant. The fan
motors are two or three-speed while the compressor motor is single-speed.
To minimize noise and drafts, we may set the thermostat FAN to LOW to run the air conditioner fans at
the low fan speed setting. This somewhat reduces the efficiency and capacity of the air conditioner, but
should only
be done during cooler and less humid weather. If you try to run the air conditioner during
warmer, more humid weather with the fan on low speed, the inside coil (evaporator) is more prone to
freezing.
Coil Freeze-Up
If the condensation that forms on the fins of the coil freezes, this will eventually block the all airflow at
the coil. The compressor, if not equipped with a defrost sensor, will continue to run and may be
damaged. Coil freeze-up can also happen as a result of restricted airflow from a severely dirty filter or
blocked vents.
Coil freeze-up can also happen when the A/C runs for a very long period without “catching up.” This can
happen when your coach has been allowed to get very warm and you try to cool it down all at once. If
you leave for the day consider leaving the air conditioner on, setting the thermostat a couple degrees
higher. When you return and reset the thermostat, the air conditioner won’t have to work as long to
recover.
Some owners have found air leaks allowing the discharge air from the main air dump to be pulled back
into the return air plenum. This causes the coil to get abnormally cold and freeze up. This can be
checked by turning the air conditioner on and removing the return air grille and filter. Place your hand
into the return air plenum. If you feel cold air blowing back into the return plenum, you should
investigate further and attempt to seal any leaks with aluminum tape.
If you hear the A/C compressor and fan running but do not feel any cold air flow, the coil may be frozen.
If you suspect this, the coil must be thawed. To thaw a frozen coil, cycle the thermostat to OFF, and the
fan setting to HIGH. This will melt the ice off of the coil. This may take some time depending on the