RV t-stats work differently from home-type units, and it sounds like the previous owner of your unit may have replaced the t-stat with a digital unit, then removed it prior to selling the unit.
I just changed my factory t-stat to a digital unit last night so the wiring is fresh in my mind. The factory unit was a Dometic Duo-Therm that controlled both the a/c and the furnace:
I find that digital t-stats just work better and also display the ambient temp as well as giving you a better read of the set temp.
Mine had 6 wires:
Red 12v+
White furnace
Yellow a/c
Blue hi-fan
Brown lo-fan
Green ground.
You colors may vary but you will have these functions.
The digital home-type t-stat only doesn't have a provision for a 2-speed fan, so a separate SPDT switch is needed to enable both hi and lo fan.
I found a non-programmable heat and a/c t-stat on Amazon, along with an RV-style SPDT switch to control the fan. Here's the install:
For the wiring, you don't use the red 12v+ wire at all, it gets terminated unused. The W furnace and Y a/c wires get connect as normal to those terminals on the new stat. The ground wire goes to the RC and RH terminals....this is not a typo. This stat uses a pair of AAA batteries, so no 12v+ is needed.
The blue hi fan and brown lo-fan wires go to the outside terminals on the SPDT switch and a new wire from the center terminal on the switch goes to the fan terminal on the t-stat.
Hope this helps.
I just changed my factory t-stat to a digital unit last night so the wiring is fresh in my mind. The factory unit was a Dometic Duo-Therm that controlled both the a/c and the furnace:
I find that digital t-stats just work better and also display the ambient temp as well as giving you a better read of the set temp.
Mine had 6 wires:
Red 12v+
White furnace
Yellow a/c
Blue hi-fan
Brown lo-fan
Green ground.
You colors may vary but you will have these functions.
The digital home-type t-stat only doesn't have a provision for a 2-speed fan, so a separate SPDT switch is needed to enable both hi and lo fan.
I found a non-programmable heat and a/c t-stat on Amazon, along with an RV-style SPDT switch to control the fan. Here's the install:
For the wiring, you don't use the red 12v+ wire at all, it gets terminated unused. The W furnace and Y a/c wires get connect as normal to those terminals on the new stat. The ground wire goes to the RC and RH terminals....this is not a typo. This stat uses a pair of AAA batteries, so no 12v+ is needed.
The blue hi fan and brown lo-fan wires go to the outside terminals on the SPDT switch and a new wire from the center terminal on the switch goes to the fan terminal on the t-stat.
Hope this helps.
