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

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!

by in Huntington, WV on October 02, 2012
1 answer 3 comments
ANSWER by on October 03, 2012
INSTALL NEW ENGINE THERMOSTAT.
COMMENT by on October 06, 2012
I figured I needed a new thermostat, but would this cause the clicking under the dashboard as well?
COMMENT by on October 06, 2012
POSSIBILITY, CHANGE STAT TO SEE IF CLICKING STOPS.
COMMENT by on October 06, 2012
Thank you!