2001 Mazda B2300 Q&A

2001 Mazda B2300 Question: Why do I not have heat but I have air conditioning?

My truck currently does not have heat, but the air conditioner works just fine. My thermostat will rise in the summer time with the air conditioner running, but when it is switched to hot air, the thermostat does not rise at all. I occasionally hear a clicking coming from my glove box area, but it is not a constant. My coolant levels seem to be just fine. Help! -
Answer 1
INSTALL NEW ENGINE THERMOSTAT. -
Comment 1
I figured I needed a new thermostat, but would this cause the clicking under the dashboard as well? -
Comment 2
POSSIBILITY, CHANGE STAT TO SEE IF CLICKING STOPS. -