Need help with Coleman TSR unit

[Natedog1971]

Hi all,
I am so glad I found this site. Recently purchased a 1983 1750 and this is my first travel trailer. My question today is: the air conditioner thermostat has been replaced as of today. The a/c runs and then shuts off and then runs again a few minutes later. Maybe it's down to temp, but shouldn't the fan still run if the switch is on to fan?

Thanks all!

Nathan

[JohnB]

Hi Nathan,

Congrats on your camper and welcome to Sunline Owners Forum.

On the AC unit, I do not know the model number of the one in your 83 camper, but I do know some on ones from the 90's and forward.

I'm not exactly sure what you are saying,

The a/c runs and then shuts off and then runs again a few minutes later. Maybe it's down to temp, but shouldn't the fan still run if the switch is on to fan?

Assuming you have an "older" AC unit and this is a Dometic AC unit, meaning at least year 2010 ish and older, (the brand news ones are different) The AC unit runs to satisfy the T Stat. The fan and compressor run together for a time period that satisfies the T stat. Once the T stat is satisfied, then both the compressor and the fan shut off. There may be a delay on the fan to run but once the T stat is happy, it shuts off.

As time passes and the T stat warms up, then both fan and compressor run again. This is how they worked.

If you want the fan to run, some had a fan switch that allowed just the fan to run, but if the fan was in "auto" mode, then the fan would cycle with the compressor.

Now knowing this, what is your unit doing? If you say it runs and shuts off, how long is it running for? 5 to 10 minutes or trying to cycle every 30 seconds which is a problem. If the T stat is satisfied, it could be doing what it is supposed too. Unless it has issues. The new digital T stats are good to control within +/- 1 deg F. The older analog ones, they could be up to +/- 3 to 4 deg F.

If you crank down the temp a large amount, say 5 to 10 degrees from ambient, it should run close to non stop trying to get to the setpoint and once at setpoint, (or what it thinks is setpoint) fan and compressor shut off. Does this work?

The brand new units are different. On those, the fan runs non stop period. And just the compressor cycles on and off. There are many of us who actually do not like this new feature. We are camping and the lack of noise is pleasing. I bought new upper unit last year and on purpose used my old control box so the system would shut down. But again, that is personnel preference.

If we need to dig in deeper on this, we are going to need a model number of the AC unit so we can look up exactly what you have. And the brand in case someone changed out the original Dometic unit. If it is a Coleman Mach, it may have been changed. I do not know for sure, but I think Sunline only used the Dometic.

Hope this helps

John

[Natedog1971]

Thanks John for the quick response. This one has a fan selector switch. I turn the fan selector on to low or high AC and reaches a level it shuts off. If I turn the fan selector to fan only it doesn't do anything. Once it warms up inside and the compressor turns back on then I can switch over to fan only then it works.
Hope this explains it better.
Thanks,
Nathan

[JohnB]

Hi Nathan,

OK, something sounds a little mixed up in the wiring. The good news is, the fan works and the compressor works, and they sort of both run to cool but something does not sound right with the wiring of the thermostat or at the AC control board. The fan only switch circuit is fairly straight forward.

In order to help better, we need to find a wiring diagram of the AC unit control board and the new thermostat you just installed.

Your post name said Coleman TSR unit, can you please find the model number of the AC unit and confirm what series Colemen it is, and what brand/model thermostat did you install?

Pictures if at all possible help too. A pic of the T stat with the cover off showing the terminals and any wiring schematic it has and if possible, the AC unit control board. We need to see what you are up against. I can do it through on line manuals but I need the model and brands.

A question, did the AC unit ever work right since you owned it? Trying to figure out if you inherited this issue from a prior owner, or it worked right for a while then broke.

Hope this helps

John

[Natedog1971]

Hi John,
Couldn't find the model number but I found the wiring schematics for upper and lower unit. This unit is a much newer unit than the original. Whoever replaced it and wired it didn't know how to read schematics. The upper unit was wired correctly however the lower was all messed up. The thermostat was wired to have a hot wire and a common going to the same terminal. The other terminal had a common going to it. I corrected that by putting both commons on the same terminal which is how it had it in the schematics. The fan selector switch was wired all wrong as well. I corrected that and now it works as designed. The thermostat turns off the compressor but leaves the fan running like it is designed. Thank you so for pointing me in the right direction.
One happy camper now,
Nathan

[JohnB]

Nathan,

Outstanding!!!

Glad it came out this straight forward once someone can read the road map correctly... Good for You!!!

Happy camping

John

[Sunline Fan]

Great job Nathan! Sounds like a great fix, and for the right price!

[Natedog1971]

Yes Fan it seems to be. We took it out to the local campground and we are enjoying it no issues to report....
Nathan

[sep]

I read the first post and thought. "it's wired wrong." Then I read further and saw that you already figured that out and fixed it. Very Nice!