Duo Therm 5 Button thermostat is blank

[gremlin]

So I went into my coach yesterday (2004 Windsor) to get her ready for summer, and the 5 button thermostat has no display. I've found the troubleshooting guides but am a little unclear on what to do next here's what I've done

1) Checked every 12 volt fues in the house control panel, all good
2) Checked the 3amp fuse in the front rooftop A/C it seems intact from visual inspection.
3) Checked the cable to the thermostat there is 12volts between the red and black cables.
4) Checked all 110 fuses, although I'm not sure what this would do since it works without any shore power to control the furnace.
5) tried resetting the thermostat by holding top and bottom buttons
6) Repleace the thermostat with a brand new one, it also shows blank


When I pulled the cold air return down I found there were three RJ11 (Telephone jack) Style connections just hanging out in there, can't tell which one might be the one to the thermostat vs rear AC vs Furnace, so I'm not sure where to connect a new temproary cable to the t-stat to see if that is the problem. Any guidance?


Any thoughts?

thank you!

[Arch Hoagland]

Is this coach new to you?

Did the thermostat ever work for you?

What was the last type of maintenance work done on the coach where something could have been damaged?

I assume you know know there is an on/off switch on the bottom of the housing.

[gremlin]

Originally Posted by Arch Hoagland

Is this coach new to you?

Did the thermostat ever work for you?

What was the last type of maintenance work done on the coach where something could have been damaged?

I assume you know know there is an on/off switch on the bottom of the housing.

It last worked last year when we last used the coach before we winterised it. The coach is not new to me, I've owned it since 2006. Yes, I needed the switch to do the reset procedure so I'm aware of it. Nothing has been done to the coach.

[Dupdyke]

Try some tuner cleaner on the black switch on the bottom. If it does not function no lights on stat....

["007"]

Welcome to irv2.
Do you have the trouble shooting guide.
I would just unplug fuses, connecting cords, than reconnect and check 12v wiring coming off fuse panel wires will become loose from road vibration and just setting wires can become oxidize.

[calhyatt]

Cycle the switch on the bottom of the thermostat like you are mad at it. Might just be a dirty slide switch. Can you use a bright light and shine it up next to the return air duct and see any connectors up there?

[Jimooo]

Do you have control voltage going to your t-stat to power it up?

If not check your 24 volt transformer.

Good luck, James

[calhyatt]

Do you have a salesman switch that might be in the wrong position. Are all the other 12v devices working?

[calhyatt]

Originally Posted by Jimooo

Do you have control voltage going to your t-stat to power it up?

If not check your 24 volt transformer.

Good luck, James

My 5 button stat is 12 volts. I didn't know there was a transformer involved. Something new to me.

[MSHappyCampers]

My 2002 Windsor uses telephone cable from the thermostat up to the A/C on the roof. The power is provided up there, not at the thermostat.

It's really strange that it used to work and now is suddenly dead and you have the loose telephone wires hanging out in the A/C unit!

One thing you might want to check. I just moved my thermostat which was located in the BR slide. The wire went under the bed and up inside the engine compartment to the A/C. There was a RJ11 telephone cable coupler in the line under the bed. If yours has one it could have gotten unplugged or maybe the two plugs are not getting good connection. I had to remove the front access cover under the bed to see the wires.

Sorry I can't be of more help on this one, but good luck!

[gremlin]

Thanks for the ideas...

A few responses

1) I haven't tried cleaning the switch on the TStat, but I did replace it with a brand new one and the behaviour is the same, so that's not the issue

2) I measured the phone connector (RJ11) at the TStat on the black and red and I get 12 volts there.

3) All other 12volt power int he coach works (lights etc) and I've pulled and replace every fuse in the coach 12 volt panel (the ones that have the thermostat multiple times)

4) The connectors I was refering to were inside the AC when you pull the cold inlet panel down, you can get the black foam out, there's a wiring box in there and next to it are three RJ11 connectors. Just hanging out there, I don't know which of these is the thermostat and which one is the furnace, and which is the rear AC (I have two furnaces and two AC's in my rig)

[Pusherpilot]

Originally Posted by gremlin

Thanks for the ideas...

A few responses

1) I haven't tried cleaning the switch on the TStat, but I did replace it with a brand new one and the behaviour is the same, so that's not the issue

2) I measured the phone connector (RJ11) at the TStat on the black and red and I get 12 volts there.

3) All other 12volt power int he coach works (lights etc) and I've pulled and replace every fuse in the coach 12 volt panel (the ones that have the thermostat multiple times)

4) The connectors I was refering to were inside the AC when you pull the cold inlet panel down, you can get the black foam out, there's a wiring box in there and next to it are three RJ11 connectors. Just hanging out there, I don't know which of these is the thermostat and which one is the furnace, and which is the rear AC (I have two furnaces and two AC's in my rig)

Gremlin,
On our 04 HR Imperial, which is a virtual twin to yours, those RJ11s plug into the controller box for the AC unit. On mine the controller is in the AC unit under the cover on the roof. I suspect that the connector box you refer to is the AC wiring for the air conditioner. On mine the RJ11s connect to each other via double female inline connectors. The T-stat gets its 12vdc from the DC fuse panel in the BR listed as airconditioner. The difference in mine is that there is a zone 3 since mine has aquahot. I am baffled by why you read the 12vdc at the RJ11 connected to the t-stat but it still isn't lit. Since you're pretty sure you have a good t-stat I suspect that there is something about that RJ11 that isn't right. There is a wiring diag that describes your system that I'll send you the address for as soon as I can find it.
Ron

[Pusherpilot]

Dredging back in memory I remember having trouble with telephone RJ11s contacts being bent and not makiing contact with the jack on the inside.
Here's the address for the wiring diags.
Monaco Coach - wiringdiagrams

Ron

[gremlin]

Thanks I'll check that out.

The female inline connectors are the ones I'm seeing underneath I'm trying to determine which one of those is the right one to try with a new cable to see if there's a cabling problem. I stuck a volt meter into the pins on the RJ11 coming out of the wall and was able to get 12vDC on the meter so I know it has power, but no display, no back light nothing on the panel at all that indicates it's working.

My wife just reported that she pulled the 3amp fuse in the top of the A/C's outside and it looked a little corroded but otherwise fine. She didn't have a 3amp replacement but plugged a 5A in just to give it a shot and still no dice. I'm wondering if the problem is in the rear AC and the fact they're tied together is messing it up. So I wonder now about yanking the rear A/c Control line reconfigure the DIP switches just to get my furnace back functional..