Question from user MeatballMarine at hvacadvice at reddit.com.

Answer:

It’s low voltage so it’s technically “safe” but I think you know a thermostat shouldn’t work that way.

Answer from user SiiiiilverSurrrfffer at hvacadvice at reddit.com.

neighbor says he’s hvac certified changed out my thermostat and said to pull this wire out if i want cold air when the wire was in even on cold it was blowing hot