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Durotherm Model 57915.331 - not cooling properly

I have a similar problem - my unit starts to cool then turns to blowing room temp air. I can hear the compressor kick on and run. It doesn't sound like there's any valves flapping or running rough (i.e. low freon). Also, I checked the voltage in the camper - I'm getting a solid 118V at the wall plug.

I also sprayed out the coils on the roof. I didn't take the cover off to clean it, just blew water spray backwards through the coils to flush it out.

After doing this, I still have the same problems.

Should I take the cover off the top and make sure the coils are clean on the back side? I've also been told these units cannot be recharged - is that true?????

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Yes, you should remove the upper cover and check the back side of the condenser as Duo-Therms pull air in from the sides and blow it through the coils from inside the shroud. This usually will cause the compressor to shut down, but only after running for awhile. When you notice that the unit is not cooling as well, or not at all, got up on the roof and remove the shroud, check to see if the compressor is actually running. If the compressor is shut off, the problem lies elsewhere in the system. Check to see if the compressor is cycling on and off or if once it is off it stays off.
If you have a wall thermostat control, check for 12VDC power at the yellow wire when the compressor is off. If power is present, then remove the control box from inside the inner shroud of the unit and check for power at the yellow wire in the there. If it is still present, check for 120VAC power at the compressor relay (black wire with Purple or Blue wire). If the purple or blue wire have 120VAC power, then the problem is upstairs either with start capacitor or the thermal overload (located on top of Compressor). If there is no power at the purple or blue wire, try unplugging the freeze control and jumper the connection on the board (blue connection, white wires) with a small piece of wire, if the compressor comes on and runs, then you have a bad freeze control. If not, then you have a bad control board.
If you have manual controls on the ceiling unit, you could have a bad thermostat. Unplug power from the unit and remove the two wires on the back of the thermostat. With an ohmmeter, check for continuity between the two terminals, if there is, turn the knob and watch the meter. You should not lose connection until the temperature you set is above the temp. inside the unit. If this is ok, then you need to check the selector switch. Also check the components in the upper unit as described in the above paragraph.

Hope this helps,


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Posted on Jul 05, 2009


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SOURCE: how to add freon to my 57915-331 duo therm camper

Normally that would be a closed/sealed system, not rechargeable, from the factory. Don't know what valve your seeing, unless someone has retrofitted it with valves for recharging prior to you purchasing it. I will say that quite often the reason for poor, or less cooling, than when new, is often due to simply needing a good cleaning of evaporator and condenser coils and fins. Has that been done lately?

Posted on Oct 04, 2011

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