Originally Posted by GIJOHN
Hello. I have a 2017 Thor Hurricane with a Coleman-Mach Heating and AC. While prepping for travel I found the coach heater is blowing only cool air, not warm/heated while connected to shore power. Research online says maybe the Sail Switch but that seems ok. TIA, I appreciate any ideas.
Just to be clear:
You are talking about the propane FURNACE which has it's own fan and ducting.
You are not talking about an A/C unit with heat strip or heat pump capabilities.
You do not have the "Fan" switch on the thermostat set to ON/LOW/HIGH. It is set to AUTO. So you are NOT talking about air coming out of the ceiling vents.
If those statements are true there are dozens of threads here that discuss propane furnace issues and troubleshooting as well as multiple good YouTube videos (RV Furnace Troubleshooting).
I recommend you review these and then return here with more specific symptoms and questions. Otherwise all you get are WAGS.