heater box question

[zetabird]

quick question did some looking dindt find anything, is the heater box temperature door vacuum or cable actuated. with the heater control valve bypassed I'm still not getting very good heat and was wondering if i had a bad actuator 

[gogmorgo]

It's a cable, yes. I've never had it happen myself, but I've seen more than a few people say their cable has slipped off at one end or the other.

The vent selection door is vacuum-controlled. If it looses vacuum, it defaults to the defrost vents.

 

My first advice on poor heat is making sure the cooling system's in good shape. Good thermostat, good flow through the heater core, etc.

[zetabird]

i kinda doubt it even has a thermostat in it, was gonna try to go overt the cooling system saturday when i can get in the shop but i got pulled ito doing some other stuff. ill take a look at the cable thanks

[cruiser54]

Here it is.

[zetabird]

wow thanks cruiser, as always on point ill look at that

[teamsmith]

If you're not getting much heat, a quick flush of the heater core valve made a big difference for me. I took some CLR, water, and an air compressor to blow it out from the small tube on thermostat and the tube that comes out of the water pump; I went backwards and forwards through the HC and got a lot of gunk out. My heat works pretty great now. 

 

here's a good video

[zetabird]

yup i work at a gm garage, one of the techs is gonna hook it up and show me how to use the power flusher when we have some free time

[cruiser54]

yup i work at a gm garage, one of the techs is gonna hook it up and show me how to use the power flusher when we have some free time

Get rid of the heater valve while you're at it. 

[zetabird]

i zip tied it open a few days ago and now its kinda getting heat, but its prolly pretty gunked up i know the one on the cherokee i had was. that was a Saturday plan. its nice to be able to bring it into the shop and work on it without being bothered. but looks like i have to work and then maybe a junk yard run 

[cruiser54]

Junkyard run for what? Not a heater control valve I hope. Eliminate it. 

[yxmj]

Like the Cruise Master says.....get rid of it.....there are a couple of good posts on here showing how to re-run the hoses nicely....and for the flush you will also get great results with just everyday household vinegar..I take the hose off at the water pump end elevate it and fill the heater core then let it sit for a bit....then just flush with the garden hose....repeat until you have a strong stream of clear water... . :MJ 1: .

[zetabird]

no lol it will be gone when i get a chance, i want to pick up a full cluster, a trans power switch, and see if the comanche i was told they had is still there

[cruiser54]

no lol it will be gone when i get a chance, i want to pick up a full cluster, a trans power switch, and see if the comanche i was told they had is still there

Why a trans Power switch? Ever seen this?

 

Bypassing the Power/Comfort Switch on a Renix Jeep

 

Remove and unplug the switch. In the harness are 3 wires One has a stripe, one is tan, and the other black. Make a 4" jumper wire with a male spade at each end. Plug one end in the cavity for the tan wire and the other in the cavity for the striped wire and you'll be in permanent Power mode. Stuff the harness back in and reinstall the switch for looks.

 

If you happen to have a 91 or 92 XJ/MJ and it has the Power/Comfort switch, just jumper the Tan and Blue wires in the harness plug.

 

NEVER include the black wire when jumpering!!!