heatercontrol

Vacuum leak and/or broken vacuum line to heater control

where do i find that line is it something i have to take the dash apart on? thx for the fast return. will that also make my ac not work?

Check the #10 fuse, it controls the HVAC system.

Shooter, Broken vacuum lines wont cause the A/c or Heater to not come on, but they will keep the doors from changing the vents (ie floor, dash, or defrost). I recommend you get a new climate control dash system out of a used truck. Hopefully this will fix your issues. It sounds like the whole dash system has went out. To change out everything, and to check your vacuum lines, and electrical connections, you will have to pull the controls out of the dash. Everything is right behind there. And in your truck the vacuum hoses are hooked up in sort of a cylinder type of arrangement. There is a circular hub with about 6 or 7 hoses hooked into it. That is your vacuum control. The electrical part only has 1 connector back there if I remember right. Then there is a temp control cable that hooks up back there as well. It should be fairly easy to replace. But it does sound like everything is shot to hell in there. Pk

dave thx i checked the # 10 fuse its good even replaced it plus checked all the other i forgot to say i have heat but no control over where it goes and no ac and t no temp control either

Does the a/c compressor cycle ???

A/C and heater are 2 different systems and its very unlikely they both break down @ the same time

If you have a electrical or leaking a/c problem heater would still work If you have a heater control problem(vacuum) ac would still work but airflow would default on defrost

johan airflow does go to defrost with hot air coming ou the windsheild vents so i take it this means a vacuum hose leaking? mmm , soon as it warms up here in mass ill check that out too,,,thx

Leave the AC out of the problem. It will not engage in cold temps. Ambient air temp needs to be something like 55°F more/less.

So, that leaves the heater control system. You will have warm air if the temp control cable is actuating the blend door at the heater core. The core will always have hot coolant running through it, so the blend-door in the plenum is how the cabin air temp is controlled. The door is located cabin-side of the heater core and the temp control cable actuates it.

Now where the warm air is directed to, is where the vacuum system comes into the system picture. There are 3 vacuum motors in the system. One of them controls whether/not you want to recirculate the cabin air or want to introduce fresh air. No vacuum to that motor will bring in outside air.

Another vac mtr controls air direction to/not to the panel registers. This vac line is blue.

The third vac mtr controls air flow to the floor/defrost/partial(to both) outlets. This is a two-stage motor. It has a red line and a yellow line to it. Red is for full floor, yellow is for partial to floor&defrost. No vacuum to this motor will default to defrost only. These vac lines are controlled by the function switch. That switch gets a vac supply from a black line that comes from the check-valve in the engine compartment.

So, what all that boils-down to is: ya prolly got a vac leak/faulty vac motor. Best way to check is with a hand vac pump. Cheap investment and a good tool to have because of its many uses. Mity-Vac is one brand.

Check the vac lines for cracks/leaks/bad connections. Check the vac motors for proper function. Usually the problem is in the lines and not the motors. Occasionally the function switch will be the problem source, but not usually.

Hope this helps

Dave S(Texas)

outside air.

forgot to put: this vac line is white

Dave S(Texas)

thanks guys for all thr hep... sure nuff was the vacuum line from the controls. seems like they are leaking .will pick up new ones next week and let you all know how i made out...shooter