A/C problems

I assume you have a wall mounted T-Stat.. And the installer mis-wired it.

My Coleman A/C has "Internal" Controls (Ceiling mount) so no such issues.

I rather like those units.. they SUCK (Meaning draw air IN via the condenser coils) so cleaning is much, much, much easier... Less to take apart.

My other air conditioner now has a Coleman fan so it sucks too.

You just joined. You need to post a LOT more info for us to help you.
1. You do NOT have an AC? But a Heat Pump? A Heat Pump will only put out warm/hot air and an AC will not.
2. Actual complete Model number of AC unit
3. Type Thermostat control
4. Did YOU diagnosis the old unit and also install the new unit?
5. It has been 8 months, did the new unit blow cold all summer long and it just started to malfunction?
6. If not a Heat Pump, do you have the optional Heat Strip which will put out warm air.
7. Year/Make/Model of RV
8. There IS a optional wire that is used from the Wall tstat to activate the Heat Pump coil.
9. Did you have a Heat Pump originally and if NOT, did you upgrade to a Heat Pump on the new 48,000 model? If so, you have to install a NEW wall Tstat. You cannot use a Non Heat Pump tstat to run a Heat Pump. Doug

Sounds like two wires reversed.
I would look at the connections at the working AC and compare wire colors to the defective unit.