how does the heater work.

[djmac]

i have an 82 j-10. the previous owner installed a ford 460 with holley fuel injection. after i bought it i noticed i could not control the temperature coming out of the heater and defroster (hot and it was 92 degrees outside) the slide lever is frozen. also i could not get any response from the heat defrost off control. it seems that some of this is vacumn controlled. i am not sure but i think the fuel injection can screw up you vacumn source????????? any rate it would help if i understood what makes the heat controls tick. vacumn???? mechanical????? both???
thanks for any help
dan

[Bob Barry]

Heater-controls are vacuum-operated. No vacuum and they don't open or close. Make sure it's hooked up to full-time manifold vacuum (EFI shouldn't affect this at all).

The Ford 460 could also have a heater shutoff valve in the inlet to the engine from the heater-hose; those usually need vacuum as well.

[J10Mike]

i'm not sure about that bob. i have an 82 j10 as well and i believe my hot:cold lever is cable controlled and that cable goes to the heater core housing under the hood. i was having a similar problem with heat always on. my lever was real loose, i checked the heater core housing and saw that the cable was broken. i just took a plastic tie and tied it back so it would stop putting out heat. when it gets cold, i'll tie it down the other way.

mike

[Crazy_Jeepman]

Temp is Cable controled, be a cable to the heater box on the firewall, all other functions of the heater are Vac controlled

[djmac]

thanks
i found the cable to heat control. i have no vacumn at the vacumn line so i will have to check that one out.