Heat pump comes on with furnace

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Our 2017 Cardinal has a switch which cycles through the fan, AC, furnace and heat pump. On shore power the heat pump comes on when the switch is toggled to Furnace. The furnace shut off after a few minutes while on shore power and the heat pump remained on. The furnace stopped working while on shore power. I checked fuses, breakers (all tight) and GFI and all working.
Back home, same issue but now the furnace is working on shore power. I disconnected from shore power and the furnace is working and the heat pump is not coming on. When I toggled the switch from the furnace to the heat pump the furnace continued to run, I assume the furnace should shut off but I don’t know.
I am thinking the switch is faulty, how would I check that out?
Any other ideas?
Thank you in advance

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After I posted this thread, a 2015 thread with the same problem popped up. I went through the thread and found the answer. The fan was set on low, and sounds like the heat pump. I put the fan in auto as suggested and only the furnace comes on. I thank all of you for your help, this is a great forum.
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