1. Replacing TrueAir Thermostat with Ecobee SI
These instructions will help you to replace your original TrueAir thermostat with a new Ecobee SI WiFi enabled fully programable thermostat

2. Reasons for the conversion
Programmable for better comfort
Control heating and cooling via the Ecobee App from anywhere with internet access
Set alerts to let you know of high and low temps
Set the fan to circulate air in your coach on a schedule
Freedom of mind that you can know what the conditions are in your coach and be able to do something about it not just monitor it.

3. From this to that!!
Orignial TrueAir
Ecobee SI

4. Turn off your 12 volt power to the coach with the disconnect switch
Remove the cover on the TrueAir thermostat

5. Take the 2 screws out from each side of the thermostat base plate and pull the plate away from the wall
Pull a little slack on the wires from the wall

6. Remove the screws holding the access panel and loosen the panel from the wall
The TrueAir thermostat has 2 plugs connecting it to the coach wiring. Pull the plugs apart and remove the thermostat

7. Take the TrueAir to a clean work area to start assembly of the new wiring
You will need approximately 6 feet of 8 conductor #18 thermostat wire available from you electrical supply or Lowe’s and Home Depot

8. You will also need male and female disconnects available at NAPA or Ace Hardware for a wire size of 22 to 18 guage
Wiring on the back of the TrueAir
Place a label identifying the 2 grey wires as #1 and #2. These are the only colors duplicated

9. Wiring on the back of the TrueAir
Cut the 2 plugs off the TrueAir about half way on the wire length allowing enough room to crimp on the connectors

10. Crimp on a female connector to each wire on the plug starting with the small 4 wire plug then doing the larger plug
After you get all the ends on the wires it’s good to use a meter and check that each connector is making proper contact and you have continuity from the plug end

11. For 12 volt dc power you need to combine the red white wire from the small plug with the red wire from the large plug and put 1 female connector on them
After you get all the ends on the wires it’s good to use a meter and check that each connector is making proper contact and you have continuity from the plug end

12. Using #16 stranded wire make up a 3 foot section to tap an additional power source for the Ecobee
You will 2 12 volt sources at the end
You can find the second power source by locating a hot terminal on the hot water heater switch or somewhere off the battery voltage indicator on the coach

13. Here we have one female connector with the red/white, red and second power source combined. Use a larger connector for this.
This will then attach to the red wire of the new 18 gauge wire for one combined power source

14. Again be sure to check the continuity of each wire back to the plug with a meter
The finished wiring harness ready to install. The 18 gauge leads are approximately 15 inches to connect to the new Ecobee

15. The wiring was done this way so that in the future if you sell your coach you can always put the original TrueAir back just put male ends on the wires and plug it back in.
This is the mounting plate for the Ecobee, the screw holes match the original TrueAir so just screw it on where the TrueAir was.

16. Find your secondary power source using a multi meter
Find your secondary power source using a multi meter. You want one that is always on not switched
Insert the large and small plug back into there relative components with the new harness on.

17. Put your panel back together securing all the screws having the new wire leads coming out the original hole.
Mount your Ecobee base plate just like the original TrueAir

18. Strip and mount your new harness into the Ecobee base plate following the wiring chart at the end of these instructions
Snap your new Ecobee SI onto the base plate and turn on your disconnect to power up.

19. This is optional: If you want to have 2 speeds for your fan you will need to install a secondary 3 pole switch. The original wiring per the chart is for a high speed fan only.
Make up 3 leads from a 3 pole switch, center lead goes to 12 volt source, then the other 2 go to P2-7 (green) and P2-9 (purple) wires on Ecobee

20. Mount your switch in a good location, have it up turns on the high fan, middle off, down turns on the low fan.
That’s it now you have a fully controllable WiFi thermostat instea of the old style.

21. Follow the installation instructions furnished with the EcoBee on setting it up. BE SURE TO TELL IT YOU HAVE 2 STAGE HEAT AND 2 STAGE COOL (not heat pump)
I hope these instructions helped on your install.
Larry

22. Suggestions:
If you decide to undertake this upgrade on your coach please take your time and be sure to study each step. If at the end you just don’t like the upgrade you can put connectors on the TrueAir again and reinstall it.
I am very happy with the conversion, I have now put a AT&T Netgear Nighthawk LTE hotspot in the coach and where ever I park it I can control the heat and A/C. My coach spends the winters in Florida and I get down every couple of weeks or so. In the meantime I can keep the system running preventing many problems that other people have had.
Hope you enjoy and any questions me at
You can download a PDF of these instructions at
Larry Puchalski
Copyrighted © 2018 Larry Puchalski

24. Wiring Locations on Ecobee SI
New Wire Color
Location on Ecobee Thermostat Wall Plate
White
Terminal W2 Aux
Orange
Terminal Y2
Blue
Terminal C
Red
Terminal RH
Green
Terminal G
Brown
Terminal W O/B
Yellow
Terminal Y
Note: Be sure a jumper is placed between Terminal RH and RC
If you will be installing the fan switch to control the fan speed you will be working with the new green wire and the original purple wire just splice on another color to that and connect to the switch and a 12 volt power source then connect the switched lead to terminal G on the Ecobee