SENDING OUT A S.O.S DIGITAL THERMOSTAT MOD PROBLEM

[TOYOURRESQ]

Hey all I need a little insight as I am pulling my hair out. I have a 1997 sunline solaris t2970 and i am trying to install a hunter thermostat 42995b with no luck. the color wires i have coming from the as is as follows:

1-white
1-green
1-blue
1-either tan or a dirty white wire
2-red wires one thick and one thin

i have a duo therm a/c unit, and the thermostat is vertical if that helps. i tried switching the wires exactly as it was on the duo therm to the hunter with the exception of the blue wire witch i put to the spst switch and did not use the 7.5v thin red wire, but i still have the other wires but its not working,i think the thick red wire may be throwing me off. i have tried to research the wire layout from the earlier post but no luck. if anyone has had the same wire layout and could help me it would be greatly appreciated.

thanks
eric

[Steve Collins]

Eric,

Did you make note of which color wire went to which terminal on the old trailer thermostat before removing it? If you did, it should be easy to cross reference those connections to the new thermostat.

And did you put batteries in the new digital thermostat? It won't work without them.

And you are correct, the +7.5vdc line should be taped off and not used. Use a multimeter to verify which wire is the +7.5vdc line, but it is usually red.

Was the thick red wire connected to anything, and what is the voltage on it? Unless there is something else connected to your thermostat, I don't think that there is any need for +12vdc here at all.

On my '99 T-2453, this was the wiring:

Function Color Hunter Terminal
--------------------------------------
+7.5.......RED......not used
Cool.......YEL........Y
Furnace...WHT.....W
Hi Fan......BLU......Thru spst switch to G
Fan..........BRN.....G
Ground.....GRN.....RC

May I also suggest that you ignore BLU (High Fan), and concentrate on getting the basic set up working first, and then add the High Fan capability after you know that everything else is OK.

[TOYOURRESQ]

IF I REMEMBER THE THICK RED WIRE HAD LIKE 3 VOLTS AND WAS CONNECTED TO EITHER THE RC OR RH, ONE OF THE TWO!!

[TOYOURRESQ]

yes i did put in new batteries, i have propane... even th furnace did not kick on its wierd , thank you for your help

[TOYOURRESQ]

Did anyone happen to come up with anything else??

thank you
eric

[Trailblazer]

I have not seen a wire set up with one thick an one thin red wire before. I suspect one of the red wires, possibly the thick one has been spliced in to fix a previously broken wire. Is there any wire slack in the wall that you can pull the wires out further to see if the thick red wire has been connected to another colored wired. It appears to me you are missing the yellow wire for cooling. If you can't pull out the wires any further from the wall, is there an access panel nearby you can open up that would give you a better view of the wires. Also did you make sure you added a jumper wire between the RC and RH terminals.

[TOYOURRESQ]

ok after a little research i found out that trailblazer you are 100% correct. sunline or someone else spliced the wires in. i took the digital thermostat off and put the analog one back on. i re-connected everything like it was before and it works perfectly with the analog ac/heat etc. my new question is this, when i re-change it over back to the digital one, how come i dont use the 7.5v wire, the analog one has a wire to rc, one to rh and then the rest w,y,g? thank you for all your input.

eric

[Steve Collins]

The digital thermostat gets all the power it needs from its own AA batteries.

The old DuoTherm needed the +7.5v to operate. Tape off the +7.5v and don't use it.

Because of whatever splicing was done, the colors may be different, but your connections should be (DuoTherm terminal labels on the left, Hunter on the right):

Cool.......Y
Furnace...W
Hi Fan......Thru spst switch to G
Fan..........G
Ground.....RC

And RC needs to be jumpered to RH.