Why is my thermostat stuck on hold?
The most likely cause of the problem is a burned-out heating element or a malfunctioning thermostat.
A permanent hold on your thermostat means you can keep it at one of its temperature settings until you change it manually. A temporary hold allows you to keep the thermostat in a temperature setting until its next scheduled period (Awake, Leave, Return or Sleep).
Beside this, Why does my thermostat say hold?