no heat

[jeepcomj]

you seem to be leaking vacuum from inside the heaterbox then...or it's got a bad seal and the air is coming out there. tell me, does alot of air come out there when it's on low or off?

you probably should take out the heaterbox and put a new seal or w/e is there...but if you have bad vacuum there's a internal problem

this fix may help, but it's not your whole problem

 

[Jayposer2000]

I put my finger over the vacuum line going to the watermixer, and can feel almost no vacuum. I follow it to the firewall, and feel a ton of suction there. But i cant seem to locate exactly where its coming from. I follow the line into the insulation, but cant reach in very far... In other posts ive read about a blending door that controls the vacuum. Is this the cable the slides in and out when i slide the heat selector on the hvac dash control? Cause i can see this cable moving under the dash.

 

[jeepcomj]

no clue. you should start a new thread for it so more people can help

 

[tow2topgun]

The blending door on my 85 XJ is located in the passenger side floorboard/firewall area. There is a orange Vac line hooked to it and it opens when in AC mode and I'm not sure but I think in Vent mode.

 

[jeepcomj]

nope, the only time that's open is in AC. in any other position it sucks air from outside

 

[jmeti000]

i JUST fixed that same problem...my heater core was totally clogged. drain you cooing system and see if you can blow water with a hose through your radiator core. if you cant, or you barely get any flowing, close the system back up and fill it with 2 gallons of white vinegar and top it off with a little water. start the jeep and let it flow around the system. then just let it sit in there for a while and work at whatever is blocking stuff. i let mine sit all day sat., overnight till sunday morn... then drained and flushed the core and system again. flow was amazing!! refill with rad. fluid/water and off you go... and my heater blows so hot i cant hardly stand it.

 

[jeepcomj]

i JUST fixed that same problem...my heater core was totally clogged. drain you cooing system and see if you can blow water with a hose through your radiator core. if you cant, or you barely get any flowing, close the system back up and fill it with 2 gallons of white vinegar and top it off with a little water. start the jeep and let it flow around the system. then just let it sit in there for a while and work at whatever is blocking stuff. i let mine sit all day sat., overnight till sunday morn... then drained and flushed the core and system again. flow was amazing!! refill with rad. fluid/water and off you go... and my heater blows so hot i cant hardly stand it.

but remember, if you live in cold weather do this INSIDE and in a HEATED garage. you don't want your sh*t cracking because you put something other than coolant in there.