well i currently have the digital thermostat controlling my roof air...
i originally used 30 amp bosch relays and after several camping trips it seems that the compressor was a little too much for them. (i wanted a year of testing with no issues before i posted diagrams etc)
i then put 50 amp bosch style relays in and have had no issues with it at all.. it regulates the temp very nicely, i have the option of running the fan only, or fan on with compressor only, or fan on all the time and compressor cycling..
so first the parts list....
i ordered extras of the molex stuff only because i like having spares and for the cost, it doesn't make sense to not have extra..
i ordered:
4-
https://www.mouser.com/ProductDetail/538-36644-0003
4-
https://www.mouser.com/ProductDetail/538-36644-0005
100-
https://www.mouser.com/ProductDetail/538-02-08-1002
100-
https://www.mouser.com/ProductDetail/538-02-08-2004
1-
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
1-
https://www.amazon.com/Honeywell-TH5...8-d89d95c82244
the thermostat uses AA batteries for power (they last about a year and a half)
you will also need to either get a 12 volt 1 amp dc power supply (wall wart style will work fine) to power the relay coils.
attached are the pinouts my unit had. the box in red is the actual thermostat you will mount on the wall. if you want variable speed fan, you will need to connect the wires through a switch like pictured. personally i haven't used anything other than high speed since i put the unit in. the only reason i can see to use a slower speed is if you put in a heat strip and wanted lower airflow to allow the strip to heat the air more.
as always, your mileage may vary, and i am not responsible if you damage your unit, or your camper.
if you choose to use 30 amp relays, i suggest using 2 of them wired in parallel to control the compressor. this will allow you to find replacements pretty much anywhere auto parts are sold.
if you use 50 amp relays then you shouldnt have any issue. i have been running the 50 amp relays for about a year now (1.5 months of actual usage)
btw the great thing about this setup is that it should be plug and play so that if it malfunctions, you can simply unplug it and plug the original controls back in if needed.
before wiring this up, i strongly suggest checking the function of the wires on your unit with a meter(what wire is hot when the fan is on, which is hot when the compressor turns on etc) and comparing them to the diagram in the pdf.