QuestionI have a 2004 27' Komfort Travel Trailer with a Dometic roof
mounted AC unit with ceiling mounted output vents. It is
operated by a wall mounted thermostat/control pad that
controls both the AC and the furnace. The thermostat as a
auto/on switch for fan control.
We have only used the AC unit four or five times since we
bought the trailer new. (We live the the northwest.) When we
tried to use the unit last weekend the unit's compressor kicked
on but we could not get the fan to operate on either the on or
auto position. After two days of the fan switch in the on-
position (I forgot to switch it back to auto) the fan switched on
and the unit worked just fine.
Obviously not very reliable. Do I most likely have a AC unit
problem or a control problem?
Thanks for your help.
Terry Peterson
AnswerHi Terry:
Thanks for the detailed question Terry. Since you have not used the hvac unit in a while, I strongly feel the fan motor bearings are getting dried out from lack of lubrication. When you accidently forgot to turn the fan back off, the fan continued trying to start. when a motor is locked up, the motor pulls higher than normal current (refered to as Locked rotor). This condition continues until the internal overload switch eventually opens up, cutting of the electrical supply. When the motor cools down, it again tries to start, repeating this senario. Evidently, the heat from the motor did something to help loosen the stuck bearings. Some motors do have oil ports on them, so add a few drop of 20 weight sae engine oil. If no ports you may try some way to put some oil to the front and rear bearing. You can spin the blade, to find out if it spins freely or if it seems a little hard to turn. If it continues to lock up, you will have to replace the motor. If it works ok, every few months, it would be a good idea to start the fan and let it run for a few minutes.
Terry, I hope this helps answer your questions. If I can be of further assistance, please contact me. Regards, Larry
