I have a True T-72F 3-Door freezer that cools well normally, but when the defrost timer kicks in (set at 10 minutes for now as a result of this issue) it never stops heating until the entire time is up, even with no frost build up. I tested it with an IR temp gun while sitting inside the unit during the defrost cycle so I could monitor the evap coil temp throughout. It was below what my gun can read at the beginning of the cycle (-5F) and gradually rose until it was 200+F over the entire coil by the end of the 10 minute cycle and 250F in some spots. The inside air was up to about 80F by then and there was steam condensing on the cieling. It felt more like an oven than a freezer. Is this normal? It seems like an awful lot of wasted energy to continue to heat so long (wasted energy in unnecessary heating and the energy to cool that back down after).
There are two wires visible in the clear drain tube coming from the back of the evaporator casing. Are these supposed to be coming from a defrost termination sensor? If so, what temp should the evap coil be getting to before the sensor clicks?
If I need a new sensor/switch is it reasonable to do myself or do I need to have a contractor do it? (I am a mechanical engineer with good electrical experience, but I'm not an experienced HVAC guy really). This is a freezer that my wife used in her smoothie shop that I plan on selling.
Thanks in advance for any help.