This is my first post to ScampCamper so patience with me please. I'm not yet sure about photos. But...
(Updated 4/17/2014 w/first photos and some notes. I'll continue to update as I work through my documentation)
...I'd like to report that I now have my overhead Polar Cub A/C and my furnace operating fully via a household type digital thermostat - a Hunter to be exact. (That's the water pump switch to the left, not fan switch.)
Yup, FULLY operational via the thermostat. (update 4/25/2014): I should clarify that this setup DOES NOT allow for independent operation of the propane gas furnace blower without the heater kicking in. This was mostly for digital operation of the AC, or the Furnace WITH heat. That's because most RV furnaces run two blowers off the same motor shaft. You can't run one without the other. This mod DOES run the furnace normally, however.) No more fiddling with the fan & thermostat knobs up at the ceiling, nor the heater controls via the manual Suburban thermostat! In fact, I've completely removed the overhead knobs and their related components. I inserted short carriage bolts with square heads into the holes left by removal of the original control knobs. (Some things in the pic may look a little askew due to the angle of the camera. Sorry.)
The Polar Cub on my 2010 Scamp, and its fan, now comes on when the Hunter digital thermostat tells it to, and shuts down, fan included, when the Hunter tells it to. I can also run the fan without the compressor if I so desire - all from the digital thermostat. And, I can also run my furnace from the same thermostat. Just like at home in the house!
The complete conversion cost a C note, doing all the work myself. There are three main components to the conversion: (1) a new control box/circuit board - about $70, (2) a digital thermostat - $18 for mine, cost is variable depending on whether you go new or used, (3) four or five wire Thermostat wire - $6 at my local hardware store, then a couple $ for an optional fan switch, and a $ or two for some female push-on terminals.
This optional switch is only needed if you want independent control of the Hi/Lo speed function. If all you want is single speed, no switch is needed - just hard wire Hi or Lo into the "G" terminal on the thermostat. You can then turn just the fan On/Off (no compressor) from the fan switch built into the thermostat.
Note: It seems most RV air conditioning techs will suggest that whenever running the AC, you should be on Hi speed. Apparently, the Lo setting with the compressor running often contributes to freeze-ups. So, for some folks, perhaps Hi speed is all they want/need and they won't need the optional switch I mention.
The entire install can be done from inside the Scamp. The only thing I needed to go outside for was access to my Fridge compartment because I chose to run thermo wire partly through there. There is NO fiddling with anything topside on the roof unless you just want to go up for a look-see or cleaning.
Here's a link to the all important control box I bought: http://www.rvproductsshop.com/catalogsearch/result/?q=Coleman+Cool-Only+Control+Package+8330-752.
It was $62.99 plus shipping. It is virtually Plug-n-Play with the top unit. For power all you need do is hard wire in the 110v with wire nuts, similar to any household junction box, and hook up the thermostat wires to the labelled connectors.
The Control Box mounts up in here on those two screws you see sticking out up inside:
The green web jacketed wires are those from the rooftop unit. They just plug right into the new control box in the center socket. It's Plug-n-Play. No rewiring or changes to make. I rerouted my 110v around to the left of the unit and inserted into that round opening into the boxed off section for wire nutting to the control box wiring. The white wire is the FREEZE sensor. The sensor is inserted into the condenser coils you can't see in the photo.
Some dealers/retailers will suggest that you need to buy a new "plenum" as well (your ceiling unit). You don't. "Recycle" the one you have. Works perfectly. That's what I posted up above in the first two pics.
I'm still updating this write-up with pics and such, but with Spring here I'm not sure how soon I'll get it done. I thought perhaps there are some members on here that might be interested in this since Summer is coming, so I'm at least posting this for now. It is DEFINITELY do-able and not all that difficult!