Upon arrival the thermostat was displaying a memory error message. Tech removed the thermostat face plate from the sub-base on the wall, allowed the thermostat to power down briefly and reinstalled. Thermostat booted back up and had to be reconfigured for proper system operation. System cycled on and heated with no challenge. Customer experienced a power outage over night due to storms, this could have caused the thermostat to malfunction due power blinking on and off. Tech replaced 20x30 air filter, dated 5/17/22 with customer supplied filter. System is working correctly at this time. Recommend having system on a regular service plan.