For anyone needing to use their furnace or AC while awaiting to get into service or parts. It actually does not have anything to do with the actual air temp, but appears to be more about the sensor reading.
I have a Fuzion 357 and have the AC issue when sensors read over 100 degrees. Assuming this same work around is effective for Furnace issues when reading under 40 degrees.
Locate the sensor for the room you wish to activate, then hold an ice pack to it to cool down the sensor. Once you get a reading 99 degrees or lower, you will be able to activate the AC unit. I used the above method yesterday to get all 3 units running on generator power.
Keystone was not any help and simply deferred to contact a service center. No matter how much detail I gave them. I needed the above work around as the soonest I can get into a service center is October