4 button thermostat repair / upgrade

[Fratto]

I am getting frustrated with the 4 button thermostat. Any input on repairing the buttons vs upgrading to 5 button or are there additional options?

[Gil_J]

The button switches and LCD display can be repaired. There was a person on eBay that had an exchange program.

I would not go with the 5 button. If I was changing control cards, which I did, I'd go to the current thermostat.

[Gil_J]

I just thought if something you'll have to verify. Some heating or air conditioning functions run through the ECC. I think they are only heating functions, but I wanted to make you aware of this.

[craiglenz]

I am getting frustrated with the 4 button thermostat. Any input on repairing the buttons vs upgrading to 5 button or are there additional options?

i have had this fellow rebuild my 4 button. He is good. Here is a link to him on ebay. Im sure this is who Gil is referring to.
https://www.ebay.ca/itm/Repair-of-YOUR-Duo-Therm-4-Button-Thermostat-Dometic-Part-3106463007/263152491868?hash=item3d451c5d5c:g:IbgAAMXQJ3xRfKT t&vxp=mtr

[Fratto]

Gil, are you saying that the newest t-stat can't talk to the ECC or that there are other work arounds required?

If that is the case, what is the draw back to the 5 button?

[Gil_J]

I just check the ECC card and it's specific to heat. So, any of the Dometic thermostats will work.

I would not recommend the 5 button thermostat because it requires you to replace the control card. If you have to change the control card, why not change it to the latest?

[Fratto]

I decide to go the cheap route and rebuild the switches. There are several internet posts that talk about this but none of them had pictures. In addition, some say to order "...H1..." switches (17.5mm in height) and some say to order "...H2..." switches (23mm in height). Maybe the thermostats have changed over time, but mine were 17.5mm.

I ordered PVA1-OA-H1 switches (DPST) ... but unfortunately received mis-packaged PVA2 switches (DPDT). Fortunately, the contacts inside are the same for both switches. Only the plunger is different. You can see in picture 12a that the bottom of the DPDT plunger has a different shape to create the different switching. The white plunger is DPST and the red one is DPDT.

The thermostat is snapped to the base at the bottom and hinges off at the top. I took the new switches apart and replaced the springs and contacts in the original switches. This worked great for all of the buttons but the temperature up button. That one was still erratic. I finally received the right DPST switches and I used the new plunger from one of those in the temperature up button. Now that one works great too. Apparently, both the contacts and the ridges on the bottom of the plunger wear a fair amount over time.

So in the end, I would replace the contacts, springs and the plunger on all four buttons. Push the button on to the plunger before you install the plunger in the switch to prevent damage to the contacts. The first time around it might take you an hour. The second time it will only take you 10 or 15 minutes. It is not hard at all and only costs a few dollars.

The etchings on my circuit board are not that close together in the switch area. I think that if push came to shove, you could easily remove and replace the whole switch with a small soldering iron and some solder removal tape. Although I think the need to do this would be very rare.

[Gil_J]

Mark, great info!

[Joe Camper]

Please take 1 more photo of it completely assembled on the wall. Thanks

What is Date 97164 do u know?

[Fratto]

Joe, I will get a pic. I have not looked up the date code so not sure. Bus is a 98.

[PrevostNewbie]

Getting ready for our summer trip in June, I just installed two of these Micro-Air Easy Touch units, so far so good.

https://www.rvupgradestore.com/Micro-Air-ASY-350-X01-EasyTouch-RV-350-p/asy-350-x01.htm

[Norman Martin]

Fratto, I upgrades to a 5 button. Had to replace all 3 boards in the roof airs. A friend of mine told me about a company that repairs the 4 button. I will check with him in the morning to see if true. I'll keep you posted.

Norman Martin
2000 CC 60408

[Norman Martin]

A friend of mine bought a rebuilt 4 button thermostat from Eric @ 303-718-6624. He has you return your old thermostat core. If I had known about him I wouldn't have had to change mine to a new 5 button thermostat. I had to change the boards out in my roof air units. Hopes this helps someone.

Norman Martin
2000 CC 60408