Ah good more info
Originally Posted by merlin5150
It doesn't do this while on "Hi" setting.
If the unit runs fine on hi during the day, that really helps on the info. Please confirm as that eliminates a lot of things.
Do you by chance ever notice wetness or water under the unit when you get up in the morning?
The thought I'm thinking of is coil freeze up on the evaporator running on low and at the outside temps of I think it is around ~73 ish. I would have to look it up but there is a point where inside and outside temps can affect the AC unit. The evaporator is the coil inside the camper above the plastic grate where you clean the foam filter.
Your 2001 ducted air unit should be close to mine, just about a 13,500 BTU unit rather than a 15,000 on the longer campers
This post you can see what it looks like up there.
There is a defrost control sensor in this too and they changed over the years where it is located. Mine is the round puck on the left of this pic with 2 black wires coming out of it. This view point is looking down from the roof. The foam filter you take out and clean inside the camper is on the bottom middle of this pic. You can see the foam filter under the control box with the yellow cable heading to it.
If you get a good qty of ice up on the evaporator it makes the unit cycle on and off a lot as the efficiency just went down hill big time from the ice up. And not work right either. The compressor try's to help but it can't and extra vibration may come from this. Our big cold storage (fruit farm) units had this issue when iced up.
I have foggy memory of my dealer telling me not to use lo on the AC unit when we bought our new T2499 in 2003. Later after researching this more I found out more of the reasons on ice up.
I'm not declaring this is your issue, but the more you describe what it does and does not do helps us hone in on this.
An AC unit that runs hi all day long and has no issues, then at night running on low starts having issues, well this leads us into this area of ice up as the blower is running slower and can't keep the evaporator cleaned off fast enough.
Keep telling us more, Do you remember the outside night time temps?
The click and noise, was this like a, click then a long hummmmm then a click and it stop? And about how long was the hummmmm?
I'm not an refrigeration expert but have worked with them in cold storage units. And then researched out and had to fix my own RV AC unit.
We use to have a SOC member who was a refrigeration service guy and knew this stuff inside and out. I have not seen him post in many years now unfortunately.
I'll see if I can dig up the temperature area where these things will cycle themselves hard. I has something to do with the dew point, the temp inside and outside all at the same time. Running the blower on lo aggravates this.
Hope this helps