Heat pump question

[dsisemore1]

I have a coleman mach a/c with heat pump. My coach is a 2016 Tiffin 36LA. According to the owners manual the heat pump will automatically switch over to the gas furnace mode if the outside temperature gets between 35-38 degrees. Mine does not do that I have to monitor it because once it gets below around 40 degrees not only does it not automatically switch to gas it starts making a loud clicking noise. Almost sounds like the plastic squirrel cage is hitting something. I turned it off and turned it on the next night and it works fine. This happened a couple of times, now I just monitor it and manually switch it over when temps get 40 degrees and no problem. Any ideas what is causing it not to automatically switch over and number 2 what is making the "clicking" noise?

[dougrainer]

dsisemore1 wrote:
Thanks Doug, The HP system is on and functioning properly but once the outside temp goes below 40 (according to a temperature gauge I have set up outside the coach) the unit will run continuously doesn't get the room warm enough to reach the set temperature to shut down the HP. Then after maybe an hour or so of continuous running will eventually start making the noise.

I would suspect the Outside ambient temp sensor is bad. Doug

[dsisemore1]

Thanks Doug, The HP system is on and functioning properly but once the outside temp goes below 40 (according to a temperature gauge I have set up outside the coach) the unit will run continuously doesn't get the room warm enough to reach the set temperature to shut down the HP. Then after maybe an hour or so of continuous running will eventually start making the noise.

[dougrainer]

Don't take the switchover temp too literal. It all depends on the outside ACTUAL temp below the shroud of the Heat Pump. On Tiffin's, the clicking noise could be just as simple as the foil tape in the ductwork is peeling up on an edge. That will make a clicking sound. Now, are you stating you have the HP ON and heating, and when you notice the outside is about 40, the HP shuts OFF and then makes the clicking sound and the Floor furnace does NOT come on? Remember, the furnace will only come ON if the inside temp calls for heat. Another clicking noise may be the defrost cycle and you hear the ice dropping off the condensor onto the HP mount pan. Another cause may be a defective reversing solenoid. Some HP units will still function all the way down to outside 32 to 34 degrees. Because the HP shroud insulates partially the outside ambient temp. You can force the furnace to come ON in HP mode. This will cause the HP to shut down and the furnace mode activate just like in outside 35 degree ambient. Lets say the interior temp is 60 degrees. Set the HP at 64 degrees. Once the HP comes on, after a few minutes, manually raise the tstat temp display to 75 degrees. That will trigger an automatic shut down of the HP and start the furnace. See if you have the same sounds or if the system functions normally. Doug

[dsisemore1]

I have two units but only the front unit has the heat pump. Sorry should have explained that in original post.

[DancinCampers]

Is this your only rooftop unit? I have 2 and the gas is controlled by the front unit only. The noise may be ice coming off the exterior fins.