Duotherm Control Center

Hi To all.
First thanks to everyone who replied. I did buy some contact cleaner and cleaned the contacts just as suggested. We are presently on a trip and I have used both A/C's separately since we only have 30 Amp service. We have also had the heat going. Everything works great. Amazing what happens when buttons do as they were designed to.
Thanks to all and happy traveling.
Keld

retiredtravelers2013 wrote:
Thanks again for all the help guys.
Keld

Your ONLY choice is to fix yourself (not advised), or send it out to the rebuilders that offer to repair and fix. The 4 button has NOT been available for over 10 years and new ones are not available. IF you decide to upgrade, then you will have to replace BOTH the roof top AC control boards as well as the wall Tstat to the NEW 12 button programmable from Dometic. Cost is about $500 to $600 if you pay someone to do the work. Parts cost are about $250 for both boards($125 each) and about $110 for the Wall tstat. Doug

Thanks again for all the help guys.
Keld

One of the big problems with the 4 button has reportedly been bad solder joints. The switches have also been known to go bad. When they are rebuilt it is my under standing that all the joints are resoldered. Can't verify as I got rid of my trailer before I ran across that problem. Cleaning the switches definitely helped though. Got a 5 button now and so far so good.
Good luck and safe travels!

I cleaned the contacts on my 4 button thermostat today, and shot a few pictures of the process. To get the unit off the wall bracket, use a knife or small screwdriver to pry down the tab on the bottom, then pull the bottom away from the wall. When the bottom is loose, lift off the top catch. Then you can unplug the phone type cord from the thermostat. The picture below shows the bottom locking tab that must be pulled down to release the thermostat.



Remove the 4 screws from the back of the thermostat.



Place a small amount of contact cleaner on each switch assembly, apply so that it runs down the shaft of the push button (where the screwdriver is pointing).



After applying the contact cleaner, work each switch assembly several times to insure the contact cleaner gets to all the contacts. Allow to dry for a few minutes before reassembly.

If cleaning the contacts does not cure the flaky operation, try straightening the contact legs. The contact legs are inside the blue part of the assembly. To remove them, carefully pry the small white lock (on each side of the blue box) away so the white part can be pulled up. Be very careful as the spring inside can be easily lost.

The contacts may also be turned around so the other side becomes the working set. This will become obvious after disassembly.



I've been keeping this thermostat working for many years by following these steps. Of course, if the circuit board dies, all bets are off.

Fred

Guy that repairs the 4 button units is:

William Hendrix
1737 Holman Dr
Erie, Co, 80516
whendrix@aol.com

Last I read he charged $85 + $10 shipping for exchange units. Comments I have read were positive on his work.

Good luck and safe travels!

Thanks for the replies.
I do in fact have the 4 button model. Dirty contacts make sense since sometimes the up/down works other times not. Same for the zone1/2.
Fortunally I do have the manual. Once we get home from this trip I'll get some contact cleaner.
Again, thank you guys. The members here have helped this newbie several times. You guys rule.
Keld

If your thermostat looks like figure b4 on page 18 of the document referenced above (4 button model), they are prone to dirty connections inside the unit. If that is not your thermostat, then the rest of this post is worthless to you.

I have the same 4 button thermostat like figure b4. I've had fairly good success removing the thermostat from the wall and spraying with contact cleaner and then working the buttons several times. Eventually, the small metal contacts inside the buttons will bend and not make good contact. You can disassemble the button assembly and attempt to bend the contact back into position, or you can reverse the contacts since only 1/2 of it is used when you push the button. CAUTION: DISASSEMBLE CAREFULLY. If that little spring goes flying about your coach, you'll spend a lot of time on on the floor looking for it. (BTDT). :)

Try the contact cleaner approach first. I generally have to clean mine once per year. I use spray contact cleaner purchased from Radio Shack.

Last year, there was a vendor on ebay that rebuilt these thermostats, so that is a possibility. I don't know if the vendor is still on ebay, but worth a look if your thermostat is defective. The 4 button model is obsolete, so the manufacturer's solution is to upgrade to a 5 button model but that option is much more expensive than fixing the old 4 button model.

Regarding your questions

1. How do I get it to change zones? Seems to be hit or miss!
2. Can I shut off one zone completely? And if so how?

Depressing the top 2 buttons will let you select the zone. You can run one or both zones in the heat pump or a/c mode. It will become intuitive once your thermostat is working correctly.


Fred

look on page 16. If this your unit save it .

http://bryantrv.com/docs2/docs/acservice.pdf