tkcas01
Roaming Fulltimer
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Joined: 10/11/2005
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I have two ducted Duo-therms with a single thermostat and remote sensors. The rear one seems hard to control. Sometimes I have to set it to 72 to be cool enough, but sometimes it gets too cold, but I keep bumping it up as high as 78 and it keeps pumping cold air - and this can be at night, with no radiant heat from the walls.
Just wondering if perhaps the thermostat is flakey, or maybe even something wrong with the remote sensor. Has anyone needed to replace either, if so what were the reasons?
Also, it sometimes freezes up because it keeps running with fan on low. Is there ANY way to disable the low fan speed when in AUTO? I don't want to just run it on high all the time.
Working out of my roaming home office... (currently here)
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jtfcons
Washington State (The dry side)
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Joined: 06/02/2004
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I had a similar issue with the two units on my bus. I read in the booklet that came with them that the remote was supposed to be mounted in the room where the second unit is installed. Well, I found that mine was coiled up inside the housing of the unit. I removed it, tested the thermistor in a cup of ice water to see that it was functional. It was, but it still bothered me that it was inside the housing, not mounted in a wall location which would reflect the real air temperature better. I removed the remote thermistor and about 15 feet of coiled up wire completely from the circuit board inside the unit and have never had a problem since. Both units respond to the thermostat when the set point requires, and both turn off when set temperature is reached, usually not at the same instant, but within a short time of each other.
These are the low profile (penguin version) of the duo-therm heat pump units. I'm not sure whether these are 13.5 or 15K units. Maybe your thermostat is different, but on mine the fan speed can be manually selected as well as automatic. I typically keep it in manual and selected for high speed.
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tkcas01
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Thanks for the reply. I also have the low profile units with heat pump, but my thermostat has TWO remote sensors - one in the front and one in the rear, so I think you had a different issue. Maybe I should take the sensor from the back and "inspect" it. I didn't know you could dunk them in ice water!
And yes, I can set the fans to constant low or high, but what I want is to be on auto, go directly to high, basically disabling low mode - seems that is when it freezes up. Course, maybe if the thermostat is not working right, fixing that would make it work like it is supposed to.
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tkcas01
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Me again. Took the cover off the rear sensor and was surprised to find it is just a small bulb, maybe the size of the striking end of a large wooden match, at the end of the wire. Clearly not mechanical.
It was touching the grill on the cover, so I wonder if that was confusing it. I am going to leave the cover off with the sensor just hanging there and see what happens. Already seems different.
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loedman1
Napa, Ca.
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Joined: 06/12/2006
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The rear unit in my Monaco would cycle off and then cycle back on within 2 minutes. I removed the remote sensor cover and repositioned the "bulb" back a bit more and made sure it was centered in the hole, replaced cover, Problem solved
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dougrainer
Carrolton
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Joined: 06/11/2007
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REMOVE the white clamp that holds the Bulb and just let the bulb sit in the white cover. That clamp can put pressure on the bulb and cause erratic operation. Doug
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tkcas01
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Good grief. Two and a half years of frustrating performance of the rear unit and this is the culprit. Night before last, the thing would not cut off and froze up repeatedly. Last night, removed the cover and just let the wire hang down and it worked like a charm. Thanks for confirming I have found the problem!
I had asked on here over a year ago about this same problem, but then I only reported the unit freezing up. Based on that, the replies typically focused on low freon levels, so here is a new thing for folks to be aware of.
* This post was
edited 08/20/08 06:20am by tkcas01 *
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tkcas01
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Just to confirm. Indeed the apparent binding of the thermistor the way it was originally installed resulted in bad info to the controller and thus improper operation of the AC unit.
As suggested above, I removed the white plastic wire clamp, but to keep the wire from disappearing into the hole and the thermistor from touching the cover that goes over it, used silicon to hold the wire in place.
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