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Quick Heater Question

jeepintexas

NAXJA Forum User
Location
Texas
Hey guys, I searched through about 20 pages of posts for an answer but I couldn't find exactly what I was looking for. My heater when on the heat position blows at my feet instead of through the vents. When it's on defrost, it does it's job.

From everything i've read, i'm thinking it's a vacuum leak somewhere on the hardline right?

What else should I inspect? It's not a real big deal, since it doesn't get too cold down here. I just want to try and fix this Jeep to a perfect running condition.

The H.O. Vac Can is kinda weird to me. it only has on line running to it. It also has another canister looking thing mounted right next to the battery. I'm used to the Renix with four connections.

Anyone have any good links to FSM type diagrams for a '91?

'91 XJ
4.0 AX15 NP231
 
ahh...okay.

that "canister" looking thing appears to be a cruise control "servo". it looks exactly like the part off my '87.

has anyone eliminated their cruise control on a 91' or similar h.o. jeep?

i don't think I think cruise control, since it's a standard.

now it's got me thinking to eliminate it all together.
 
I was just looking at my fsm for my renix, about the heater problem. It doesn't mention anything about heat not coming through the vents, only about heat not coming through the floor outlets and little or no air from the defroster vents.
 
Not sure where you are going here.

Your 91 w/NP231 probably has a D30 CAD front axle with a vacuum motor. If you do, and you eliminate the vacuum reservoir, then forget 4x4.

If you have a vacuum problem, and say you have the air blowing on your feet, then under acceleration or pulling a load the engine vacuum drops and then the air will default to the defrost position. No or poor vacuum then the system defaults to defrost.

Now, you should have a vacuum reservoir behind the front bumper, passenger's side. The line running to it likes to break in the area of the battery, but anytime you work in the engine bay you risk breaking the hard vacuum lines, they are fragile and get worse with age.

Many like to relocate the vacuum reservoir into the engine bay, eliminating a lot of the problematic vacuum line.

Cruise control can be had with standards, just requires an extra switch for the clutch pedal. I don't know if any XJ with a manual transmission came OEM with cruise, but other vehicles do and there are aftermarket kits.
 
You know, unless you have the symptom of air switching to the dash vents on acceleration like Joe suggests, this sounds normal. HEAT blows at your feet. DEFROST blows on the windshield and somewhat out the dash vents. BI-LEVEL will come out the dash vents. I agree with Joe that relocating the vac res is a good idea. And yes, you can eliminate the cruise control quite easily if you want to. I did it on my 88 XJ.
 
Thanks, I figured my problem out. When the thermostat is turned up and the setting is on vent it blows air through the front vents. I feel like an idiot, but I did learn something.
 
I just learned this too :dunce: - vent position will heat if you have the temp knob set to heat, and it'll blow out all the vents and whatnot.

Also, a standard can have cruise, don't eliminate that solenoid just yet. If there is a button on the end of the turn signal stalk that is your cruise enable button, and the instrument cluster has a light on it somewhere that will tell you you need to upshift.
 
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