Thermostat mod

[LeMond]

Hi I hope someone out there has the solution to my problem. We are redoing our bus and want to hook up a battery operated thermostat to our Coleman air unit. We purchased the circuit board with relays that will convert the ceiling air to a ducted unit. The 120v power supply is installed, however we cannot figure out how to wire the thermostat to the relay box. Please see photos. The thermostat is a Hunter model # 44155C. I intend to put spade connectors on the wires for the relay box, I was just trying to see if this wiring configuration worked. All ideas are welcome. HELP!!!!!  I checked with search and did not find what I was looking for.    Thanks, Chell

 

[Ernie Ekberg]

do you have ducts in your coach? I wouldn't have a clue how to wire this.

 

[Ken & Sheila]

Several issues.
How was the original T-Stat wired?

Newer T-Stat home systems are designed for 24 volts, not 12 volts.

I also don't understand what a relay has to do with converting to ducted air>

I would think the relay box would have come with instructions for 2,3,4, and 5 wire systems, but that wouldn't solve the issue that your coleman will not be supplying 24 volts.

ken

 

[LeMond]

RE: The thermostat is battery operated so we may be able to use it (hope, guess, pray). We are putting ducts in the wiring chase that has been built down the center of the bus. Bruce at Register RV (in Brooksville, FL) called Coleman and they said this is what we needed to convert our Mach 3 into a ducted system. Of course they want us to use the $75.00 thermostat that they sell, but I know others have used battery operated thermostats in their coaches and it worked. ***Sigh***  We do not have the 12 volt wiring run as we have 120v up and running. That is why I wanted to go with a battery operated thermostat for now. We can add 12v after we're in the bus.

 

[Jeff]

Our battery operated Hunter will accept 12 or 24 volts but I couldn't find one with the outputs for our Coleman to switch over from heat pump to propane when the temperature differential exceeded 3 degrees.

 

[LeMond]

We only intend to use ours with the AC. Still....no luck figuring out how to wire this thing.

 

[Icemaker]

We only intend to use ours with the AC. Still....no luck figuring out how to wire this thing.

If the A/C unit does not have a 24/12 volt power supply to control the operation of the unit than you will need to supply one...
The 120 volt is only to operate the fan and compressor...how it is "switched on/off" is because there has to be a relay is used to supply the power to the fan/compressor & electric heat strips too.
The battery in those t'stats is only for the memory of the same and to run the logic...the internal relays switch the unit on and off...they care less if it is 24 or 12 volt and not even if it is AC or DC voltage...as long as it doesn't exceed the rating for the contact loads ...
they do make t'stats that switch line voltage [120/240 volts] but are almost never used in a "residential" application, exception is in electric heating units.
So to cut to the chase you need a "control" voltage and it is probably going to be supplied from an external source as I believe that the roof top A/C units don't...I could of course be wrong on that point.
I hope this helps and if I'm adding mud to the troubled waters i am sorry.

George

 

[Ernie Ekberg]

Enlighten me- your 89 Bluebird has a wiring chase down the center of the coach? Did you have to lower the ceiling to do this?

 

[Jammer]

Most 24 volt ac thermostats work acceptably well for RV use on 12 volt DC.  You will need a battery, but you've done that.

The Rc and Y terminals are the ones you want to use to control the air conditioner compressor and the Rc and G will control the fan.

Wiring will depend on what model of Coleman air conditioner you have.  If yours is wired like this:

http://www.rvcomfort.com/pdf_documents/1976147.pdf

.. then you will want to connect as follows:

A/C Blue:          coach 12v ground
Thermostat Rc: coach 12v fused hot
Thermostat Y:  A/C yellow
Thermostat G:  A/C green

The Coleman thermostat would have a high/low fan switch.  The way I've described the wiring you will have high fan only.

If your A/C is different than the one in the link then you might need to wire things differently.

 

[LeMond]

Ok here's the update on the t-stat....I purchased a universal adjustable voltage adapter from Wally World for $18. I cut off the end and wired this into the Coleman $75 t-stat and the AC power and neg wires. I made sure the polarity was correctly set, set it to 12volt, and plugged it into a regular 120v receptacle. It works beautifully. I have high and low fan speed, the condenser kicks on and off within a 2 degree call for air, and it was a cheap and easy fix until I get the 12volt run. Thanks for all your help, I appreciate the time and effort  .  Earnie - We are building this from scratch. We decided to build a chase down the center (3 inches deep) in order to have a place to run our wiring and duct work. We are shorter than the lowered center area so....why not run it all in there. With removable panels it is so easy to get to. I am putting a video together for youtube. I will keep you'all posted. Thanks again.........chell

 

[LeMond]

Here are some pics to go along with my last post. I had to get them off the phone before I could upload them. Not as easy as it sounds...LOL Pic #1 is the chase that drops down 3 inches and runs down the center of the bus. Pic #2 is the adapter I used to convert 120v to 12v so I could run my AC.