My heater is stuck on defroster and the switch won't change it. I freeze my @$$ off every morning

 

It could be lots of things - a vacuum leak, the vacuum reservoir underhood could be bad, or the one I had a problem with, the selector switch in back of the face of the HVAC controls. It looks like a disc with a whole bunch of vacuum lines going into it. I doubt it is any of the actuators if you are stuck on defrost. That is the default setting.

 

what would i need to check on the back of the controls? just make sure everything is hooked up?

 

I am not really sure if you will see anything wrong with it. When I had the problem years ago I remember going through the vacuum lines and checking for leaks. I swapped the vacuum reservoir and it didn't work. The only thing left to try was that control switch on the back of the HVAC controls and that did the trick.

 

The vaccuum lines are what you'll wanna check - they're the multi-color lines, should be 5 or 6 of them grouped together. If those aren't sealing well, there won't be enough vaccuum pressure to open/close the doors to direct the airflow. If i remember correctly, all of those lines go to doors except for the PINK line, which leads out through the firewall and connects to the vaccuum lines in the engine bay. I've found the connections between the pink line and the line in the engine bay are often the problem. If there are any small leaks, a little bit of vaseline can help seal them temporarily.

 

Ok I'll try that

 

Oh also my blower blows more air into the engine bay than in the car and one of my buddies said that was a "factory option" is that true? I obviously doubt it

 

Definitely not an option...

 

Yeah, if "broken" was a factory option... where does it blow air into the engine bay? I *have* heard of a few people re-routing their system so that the blower motor forces air into the intake, but that would require some serious hacking and be pretty obvious.

 

Does your heat cool lever slide like it has a hold.Pull the whole thing out and make sure the screws that hold the vacuum are intact.

 

It has some resistance, but I'll check it out in the morning

 

I took it out but didn't see anything cut or loose, and now the vent selector lever thing just slides back and forth loosely

 

It sound like your cable,check under the dash on the right hand side and see if the cable is attached to the heater box ,if so, try to move the lever on the heater box with your right hand and the hot -cold lever with your left at the same time.Try that 1st then we'll move to the next.

 

Sorry it took so long but yes that lever works

 

are you sure your heater isn't bypassed????you should still get heat from your defrosters.

 

It has heat but the fact its not blowing directly on me and it seems to always be cold in my car

 

oh- just a thought. The heater cores in our cars are somewhat of a pain to fix. Someone could have bypassed your heater core.... In addition to you having issues with your controls.

 

Mine is very sluggish to change. Like if I have it on defrost, and want to change it to VENT, I'll have to switch it all the way to MAX to get the air started out of the front vents, then I can switch it to VENT.

 

the way I checked mine was to use a hand held vacuum pump to make the doors open and close to rule that out then pumped up the pink line and see if it holds vacuum . My line was broken in the engine bay right above the distributor ( it melted somehow ).

 

Thank you for the sugestions on this thread. I had my heater stuck on defrost too and thought maybe it was the dash unit. After reading this I found the two hoses coming out of the firewall - one was attached to the heater bypass and the other one was open to nothing. I went to AutoZone, bought some tubing and vacuum adapters. Hooked the hose that was going no place up to the plenum and low and behold, now the airbox will switch like it should. Thank you for the answers to solve my issue.

 

Both of my hoses are hooked up as far as I could see

Where would I hook a vacuum pump to? As u can tell I'm pretty new to any kind of hvac/heat stuff, buuut I'm slowly learning