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towpro's avatar
towpro
Explorer
Jul 21, 2015

AC and humidity problems.

I have the Coleman Mach 8 in my wolf creek. This weekend is the first I have played with the AC.

The AC definitely works for the small space, I can cool temps from 100 down to the lower 70's in an hour or so.
Humidity drops right along with temps.

This Coleman has the controls on the unit.
Once the compressor shuts off the fan continues to run inside, the humidity will rise fast. I mean from 50% to 90% in 10 minutes.
As soon as the compressor comes back on the humidity lowers again.
High or low fan has the same problem.

I feel that as the fan blows over the coil it must be evaporating any moisture remaining on the cooling coil which raises the humidify inside the camper.

Everything is new, purchased this spring. I pulled AC cover and coil cover, yes the water is running out through the foam that they put in the tray. (and it has the REV B fan for those of you following the cracked fan thread)

Is this just how these units with the overhead controls work?

I am ready to install a 20amp relay that is controlled by a low voltage circuit and a wall thermostat that will turn Electric off to the AC instead of leaving the fan running when not calling for heat.
NOTE: Thermostat will have 5 min delay so it can't turn AC back on until delay expires. than you control the fan speed on the overhead unit.

I did this to my last truck camper but it was because the temp swing using the AC overhead controls was driving me crazy.

29 Replies

  • I'm looking at a delay myself and find its easier to get a timer that will carry the smaller load of the fan than it is a heavier duty one
  • Thanks Popeyemth.
    Yes that is what I am doing.
    but I still want to be able to use the Honda 2000. So after I am done this mod I will take startup load measurements and see if I need to add a startup delay to the compressor (2 second should work).
    This way the inside fan starts first, than the compressor starts :)
  • its the 9200. I am heading to an area of PA where I will probably net even need the AC this weekend, but I think I will build the AC mod before we start heading down to the coast in August - November.
    I will document what I did in case others have the same need.

    Thanks for the replies.
  • I have the same problem humidity goes up and down with the cycle of the compressor. The moisture is evaporating back in the air. Only fix is to cycle the fan on and off with the compressor. I have plans to set it up to do it but just haven't done it yet.
  • You WANT that water to run off the roof away from your AC. If it's running water off with high humidity outside it's working. If the drain becomes clogged water will back up into the camper thru the unit itself. If is humid outside and no water is running inside or outside then the unit is freezing up. It's not running fast enough to stay thawed. Run on high fan for a while to circulate enough warm air to thaw it out then set it on high cool. My AC tech told me a long time ago when we had this problem in a 5er to always run the AC on high in high humidity, just turn the cold control to warmer if it's too cold in the camper. Only run on low fan when the humidity outside is low. Since I've followed that rule we've had no further problems in any camper we've owned. I always check the drain for bug obstructions frequently if there's no water running and after each long term storage time. Keeping the filters really clean on your inside part of the unit makes a difference as well. At least that's our experience with 13,500s and now the 9200s and 16 years with camper ACs.
  • I am dumber than a boot when it comes to A/C. If it is of any value to you, I have the Polar Cub 9200 btu. It definitely has water coming off the roof.

    Wayne
  • Now that you mention it I think I am experiencing the same thing. I guess I need to check mine as I don't think I've even seen any water come off the roof. I rarely use the a/c so I haven't got around to it... also hate heights :(