Duo-Therm Control Center Reset
After setting the dip switches in the electronic control kit, do a system reset.
1. Turn the ON/OFF switch to the “OFF” position.
2. Simultaneously depress and hold the MODE and ZONE push-buttons while turning the ON/OFF switch to “ON”. FF should appear in LCD display until the mode and zone push-buttons are released.
3. When a dip switch is turned on after the initial configuration, a system reset will need to be done before the Comfort Control Center will recognize the updated selection.
Duo-Therm Control Center Repair
My RV is equipped with a Duo-Therm Comfort Control Center that controls two roof air conditioners with heat strips. After it became progressively more difficult to change the climate settings using the panel’s buttons, I decided to purchase a new unit. Lo and behold, I discovered that the four-button control had been discontinued several years ago. I was told that I would have to buy a five-button control center, plus a new circuit board for each air conditioner. While the price varied by source, the cost would come to more than $400 plus installation. So, I decided to examine the switches and discovered that my problem would actually be simple to fix.
Here’s what was causing the problem. After many years of use, the brass contact switches had bent, and some of them were no longer making contact to create a good circuit, resulting in difficulty in selecting the desired setting. The following solution corrected this problem.
First, turn off the air conditioner switch. Remove the control from the wall plate using a tool to spring the retainer at the bottom rear. Unplug the telephone line. Remove the four screws holding the cover on the circuit board. Carefully release the clip on each side of a button, holding the button so it won’t pop off. (Longer clip toward the on-off switch; spring goes onto the peg.) Carefully lift the button from the base. There are two brass pieces inside each switch that you must individually remove. Observe carefully so you know how to replace them when ready. Lay the brass piece on its solid side with the three legs up. Notice the small elbow bend in each of the arms. The problem is that over time, the bend in the arm has straightened just enough so that it does not make contact with the solid back when the button is depressed. To correct this problem, push in on one end of each arm to make a sharper kink in the arm, thus shortening it enough so that it will make contact with the switch when the button is depressed after the unit has been reassembled.
Only the outside arms on the right side are in the circuit. Before bending, try switching the two brass contactors, one switch at a time. Roger Kittelson, F88803, Whitney, Texas
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For those with thermostats that still work but don’t respond to buttons well, here’s the fix, no soldering required.
It would take multiple buttons pushes to get my thermostat to switch mode, and it got frustrating. I’ve heard of disassembling the switches to clean them periodically but wanted a better fix. So…
An order to Mouser Electronics for new switches, I bought five @ $1.22 each. They are exact replacements.
Mouser number PVA10AH2
Mfg. PN: PVA10AH2
These are DPST momentary 23mm pushbutton switches.
Turn the thermostat off. Remove the cover from the thermostat, it snaps on.
Remove the screws that hold the circuit board, unplug the cable from it. This is an electronics board so treat it gently and ground your body (touch something substantial and metal), don’t shuffle over the floor in wool socks holding it, etc. to eliminate any static charge before touching it.
Set it on a padded surface on the table and look at the switches. Break out the reading glasses. Using a small screwdriver or knife tip, you can release the retaining clips that hold the components of a switch together. Release clips, withdraw the top, spring, and contacts, noting how they are inserted. They will only go in one way.
Now, take one of your new switches and do the same. Use the new parts in the old switch housing and snap the switch back together. They have pins on them for soldering into a circuit board but you won’t be using them. You’ve just rebuilt the switch.
Five minutes max. It sounds far more complex than it is. There is a spring in the switch that can pop out, it really doesn’t matter though as you use the new spring. Repeat as necessary for any other hinky switches and carefully reassemble the thermostat.
I didn’t take pictures of the procedure and it’s pretty self-explanatory once you look at it but can and will post pix if necessary. I enjoy this fix on a daily basis and hope you do also. Chuck Pearson 1996 U295 36′
On the A/C board I test all thermostats on (#3106482.015, which probably was used for many years with the four-button Comfort Control Center) the output colors labeled on the board for the fan are: (not related to wire colors)
low – red
med- yellow
high – black
auto – violet
You should check for continuity from the incoming neutral to the fan neutral – all power off for safety. Obviously an open 120 volt neutral to the fan would stop normal fan operation. Wouldn’t it be simple if this is your problem?
With the120 VAC on logically, the start “capacitor” would be engaged for starting all three fan speeds. Placing one of your AC voltmeter probes on the incoming neutral and then the other probe progressively on each fan speed output pin should show each of the 120 VAC outputs to the fan. If the fan rotates slowly and doesn’t come up to speed or just hums, it may be just the start relay that is bad. No rotation or hum, it might be a bad motor. No voltage on the board’s fan pins may be bad relays coils or their contacts.
The middle position large relay (K1) is for the compressor and the outside position large relay (K2) is for heat strips.
If your board is the same number, I have some replacement AC boards so upgrading to a 5 button system should not be necessary. Should your thermostat be the problem (doubtful if the display shows all the fan speeds when selected), I have those also. If Dometic does not support these air conditioners with parts any longer (give them a call), a motor shop should be able to find a replacement motor or capacitor for you.
Jim 2002 U320 5/24/13