Recommended Mach 8 Plus AC w/ Heat Pump and Components to Replace a Coleman Mach 10
Published 09/07/2026
Products Featured in This Question
Question:
Good morning .... I curently have 3 Mach 10 15K units on my GD 390RK, AC only. They are connected to Coleman Thermostats 9420-381. I would like to replace them with Mach 8 Plus units with Heat strips in 2 of them. Do I need new interior trim panels with the Mach 8 units?
asked by: Thomas T
Expert Reply:
You sure do Thomas and good morning to you as well. The Mach 8 Plus units do indeed require a air distribution box or trim on the interior of your Grand Design. To replace your three Coleman Mach 10 15K AC units, you will need the following parts and the quantity listed next to them:
Qty 3 item # CM74MR in black or item # CM95MR in white - Mach 8 Plus RV AC w/ Heat Pump
Qty 3 item # CM48GR - Coleman-Mach CHILLGrille Ducted Ceiling Assembly or item # CM98GR if your Grand Design has a ductless setup.
Qty 3 item # CM84MR - Coleman-Mach Heat Ready Heat Pump Control Kit
Qty 2 item # CM24MR - Coleman-Mach 120 V Heat Strip Kit
Qty 3 item # CM46MR - Coleman-Mach WiFi Thermostat for RV Air Conditioners and Heat Pumps or item # CM76RR for a standard thermostat.
Please note that, your Coleman Thermostats pn 9420-381 are not compatible with the new R32 Mach 8 Plus AC systems. This is the same for the air distribution boxes. Without knowing what model year your Grand Design is I wasn't able to tell if you have air ducts, which is why I recommended options for both. Each of the AC units will also need a control box. You will be able to reuse all of your existing wiring for powering the system and the thermostat wires controlling them.
What rooms or areas in your Grand Design are going to have the new heat strips in them? Feel free to answer this and throw in any other questions you have, where it says Add Comment.
(click to enlarge)
(click to enlarge)
(click to enlarge)
Product Page this Question was Asked From
Coleman-Mach Heat Ready Heat Pump Control Kit
- Accessories and Parts
- RV Air Conditioners
- Heater Kits
- Coleman-Mach
more information >
Continue Researching
- Q&A: Replacement Screen Frame and Interior Trim for a VD0433 Roof Vent
- Q&A: Recommended SnapPad Jack Pads for a HWH Leveling System on a Motorhome
- Search Results: hitch receiver
- Shop: Trailer Hitch
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Shop: SnapPad HiWay Plus Jack Pads for HWH Leveling Systems w/ 8" Round and 10" Round Jack Feet
- Shop: SnapPad HiWay 8 Jack Pads for HWH Leveling Systems w/ 8" Round Jack Feet - Qty 4
- Shop: Ceiling Garnish for Ventline Roof Vent - 4-1/4" Leg - 14-1/4" x 14-1/4" - Birch White
- Shop: Replacement Screen Frame with Screen, Rocker Switch, and Wire for Ventline Roof Vents - Birch White
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Article: Trailer Wiring Diagrams
- Search Results: trailer hitch
- Shop: Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Shop: etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2"
- Shop: Trailer Wiring
- Video: Curt T-Connector Vehicle Wiring Harness Review C56040
- Search Results: trailer wiring
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: How to Choose the Right Trailer Hitch Class
- Q&A: Lug Nut Torque Chart for Trailer Wheels
- Video: A Look at the Power Mountain Tallboy 6 Ton Off-Road Bottle Jack with a Military Cargo Trailer
- Shop: Suspension Enhancement
- Search Results: trailer tires and wheels
- Video: How to Choose a Trailer Brake Controller
- Search Results: trailer hitch ball mount
- Article: How to Measure for Trailer Hitch Drop
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Shop: Brake Controller
- Video: The Low-Down on the Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Shop: Gooseneck Hitch
on Accessories and Parts
Thomas T.
9/7/2026
Jerred ... Thank you .... it is a 2024 GD 390RK .... Planned Mach 8 Plus units with heat strips in Kitchen and Bedroom .... Mach 8 Plus without heat strip in Living room (using current propane furnace) ... Current wiring is Red, Blue, Yellow, Green, Brown in the Bedroom and Kitchen .... Red, Blue, Yellow, Green, Brown, White, Orange in the Livingroom. +12V DC Power Red 12V Ground (Negative) Blue Cooling Compressor Yellow High Fan Speed Green Low Fan SpeedGray BR Furnace / Heat White (Current Livingroom only) I know that the Orange is for the reversing valve when there is a heat pump. The wire bundle in the kitchen has the White and Orange wires cut back and not connected. Does the new thermostat utilize the same wires plus I will need to connect the White and Orange wires in the Kitchen and Bedroom? It looks like the pictures of the CM76RR use one white wire and one white wire with a black tracer .... I assume the white with black tracer would connect to the orange wire for the reversing valve.