Question: I've searched a lot and can't quite find what how to solve this one. I installed an ecobee smart thermostat, which didn't work with 5 wire connection so I switched to their PEK module with only 4 wires. With this wiring the heat is working fine, but the cooling doesn't (the compressor doesn't kick in, and the fan is blowing ambient air). Anyhow, I tried to map my wiring and this is what I have. Looks wired to me that the Rc is jumped with the common. Any ideas how to fix it? [![enter image description here](https://i.stack.imgur.com/98bdj.jpg)](https://i.stack.imgur.com/98bdj.jpg)

Answer: 
I think it is the thermostat switch. They fail when they age and can be replaced. They have a bimetal plate in there and sense the temperature with a long tiny pipe which transfers the temperature from the cooling elements. Normally there are two for each area of the fridge.
A few things to check:

* Does the outlet always have power? If connected to a light switch, that could be a problem.
* Is the refrigerator level?
* Does it have an ice-maker or water cooler, that could be causing an issue (e.g. overflowing and/or freezing)?
* Are there separate temperature controls for freezer and refrigerator that need to be set?
* Is there airflow around the condenser coils?