Look for soot accumulation around the blower flange

such as 15-52 psi

and unit heater series

Mounting Versatility: Dual hub and foot-mount options for quick installation in field junctions or equipment panels

which is a primary cause of short circuits in HVACR refrigeration systems

Ecobee EB-PS-01 Power Supply Look for soot accumulation aroundThe Ecobee EB PS 01 Power Supply is a dedicated external 24VAC transformer designed to provide reliable common wire (C wire) power for smart thermostats in systems lacking a built in 24V supply. Engineered to eliminate thermostat power cycling and connectivity issues caused by insufficient voltage, this power adapter ensures a stable 24V AC, 40VA output suitable for the entire Ecobee lineup, including the SmartThermostat with voice control, Ecobee4,