Well winter is here and since its been on average 20 degrees the past week, having only my defroster sucks. Fan works on all four speeds and you can switch the fan off as well as the heat and cold switch works, but no matter what selection you choose, its only the defroster. I figure its gotta be a vacuum issue somewhere but where should I start?? BTW, this is in my 1996 Cherokee. Thanks anyone.

 

Check your vacuum lines

 

And the back of the heater panel on the dash it runs on vacuum if it is disconnected or you don't have vacuum it wont work

 

All of the lines are plugged into the back of the control box but i wasnt sure if it might be more with the vacuum ball thing that opens and closes the different heat doors? And where abouts is that located to check? Thanks

 

If you're talking about the vacuum ball, its located on the pass. side of the front bumper.

 

Isn't that ball only for the cruise controlled though???

 

Pretty sure its for everything some are round some are foot ball shaped.

 

X2

 

I found myself with only defrost on my 96 and found that my vacume ball had a hole in it from where the mounts broke off. I wrapped some duct tape over the hole and around the ball and its worked just fine for two years. It controlls the heater selection and the cruse control and maybe more, Im not sure. If you need to get by you can just plug the line.

 

I cracked thay ball when I built my front bumper and taped it up and threw it next to the ac condenser. It holds vacuum enough for the cruise control though so you would think it would have enough to control the vents. I found a really small plastic lime last night that was broke and fixed the section with rubber vacuum hose and zip tied it tight so could there be more lines broke like that too? Or does the vacuum canister need to hold even more vacuum?

 

I have a question along the same lines. My blower motor switch and motor work perfect, and the selector works good too. When you move it to different positions, it sends the air where you tell it.
Only problem I have is that when you put the temp lever to hot, it blows cold and I can go look at the heater valve and it hasn't opened to let the hot coolant through to the heater core. If I move the heater valve myself then it works. Took the vacuum line off and there was no vacuum there.
Do any of you guys have vacuum diagrams on to where the vacuum is routed through the heater system?

 

Many complain about this pos heater valve. They bypass it. Remove it, and run the hoses directly to the heater core. If your vacuum hose has no vacuum, look at the other end of it. Is it connected, or just hangin'? If it's just hangin' then that might be why it wasn't working. Good luck

 

You could just zip tie it for the winter season as a temporary fix. We had to do that to my friends ranger

 

Get another ball. Replace any compromised lines.

 

How do you get to the lines after they break through the fire wall? Do you have to pull the entire dash apart? I must be on the right track cause now I've got at least 30% floor and 70% defroster