# Heat/AC **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [December 22, 2008, 11:47pm UTC](https://community.cartalk.com/t/heat-ac/23776 "2008-12-22T23:47:51Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![diyguy](https://avatars.discourse-cdn.com/v4/letter/d/f19dbf/32.png) [@diyguy](https://community.cartalk.com/u/diyguy)\ **Post date:** [December 22, 2008, 11:47pm UTC](https://community.cartalk.com/t/heat-ac/23776/1 "2008-12-22T23:47:51Z")
I have a 2002 Ford Explorer (V6) and the temperature control for the heat/AC is malfunctioning. When you try to change temperature or vent settings (not fan speed) you hear a thunking sound coming from behind the dash, and you either get very hot or not at all hot temperatures. I think the culprit might be a vacuum hose, but I’m not sure. Any help narrowing down at what and where to look would be appreciated. ---
**Author:** ![Beadsandbeads](https://avatars.discourse-cdn.com/v4/letter/b/c57346/32.png) [@Beadsandbeads](https://community.cartalk.com/u/Beadsandbeads)\ **Post date:** [December 23, 2008, 1:00am UTC](https://community.cartalk.com/t/heat-ac/23776/2 "2008-12-23T01:00:08Z")
Does this have electronic controls (thermostat) or manual (knobs)? The blend door is probably electrically-controlled. It sounds like the door is getting jammed and then freeing itself. If probably will get stuck soon. They can be hard to get to (pull the dash back), but I don’t know for the Exploder. ---
**Author:** ![diyguy](https://avatars.discourse-cdn.com/v4/letter/d/f19dbf/32.png) [@diyguy](https://community.cartalk.com/u/diyguy)\ **Post date:** [December 24, 2008, 7:13pm UTC](https://community.cartalk.com/t/heat-ac/23776/3 "2008-12-24T19:13:25Z")
I have manual knobs. Also, the thunking sound is repetitive until you run the fan at full blast. ---
**Author:** ![tardis](https://avatars.discourse-cdn.com/v4/letter/t/f0a364/32.png) [@tardis](https://community.cartalk.com/u/tardis)\ **Post date:** [December 24, 2008, 9:07pm UTC](https://community.cartalk.com/t/heat-ac/23776/4 "2008-12-24T21:07:04Z")
A common problem for those is for the plastic blend air-door to break where it connects to the motor. This sounds like your problem. The blend air door is electric, even with the manual climate control. It’s a cheap part, but a lot of labor is involved in changing it out. There are some work-arounds that might work. Search the web for them.