I have just bought another 98 cherokee. I thought it to be in better shape than it is. I did get it started and warmed up, but no heat at all.
I drained the cooling system and back flushed the heater core. Flow was good and the lines did get hot when running.
I'm aware that the selector may be bad as I can hear it changing the way the air moves, but it does not shift to the correct vent.
But my concern is mostly with the heat as winter is approaching. It seems that the heat should be coming from on vent or another.
Where is the heater control valve on this jeep? I read somewhere that it is operated by a vacuum switch. What info I have gleaned from the web thus far was based on a 98 grand cherokee.

 

Its between the heater core pipes and the water pump/t-stat pipes, sort of behind the battery.

If the heater pipes go straight from the WP/T-stat to the heater core then it's already been eliminated.

I can't remember if it was attached to the body or just sat in the rubber hoses. I've already eliminated mine, but if you want a picture of where the vacuum tube comes out of and what it looks like, let me know.

I'm going to guess it's already been eliminated on that Jeep. You couldn't have back-flushed the heater core and missed it.. It's pretty obvious, right on top and about 8" away from the heater core inlet/outlet. If your hoses going in and out of the heater core were hot, I'm going to guess you have a problem with the blend door/HVAC dash unit/vacuum.

 

I sere nothing inline from the tstat to the firewall. I'm still lost as to why no heat is anywhere.

 

The HCV has been eliminated then. The 97+ pre-moulded hoses fit so nicely that it really does look like it came that way from the factory.

You have to just start the diagnostic process and go a step at a time.

Do you get any fan output from the vents? I typically run "Vent" which should come out the upper vents by the door and the vent in the center of the dash. "Heat" should direct some air flow down to the foot-wells. Defrost should obviously direct air to the windshield.

The default position (the one if there's a major vacuum leak) is "Defrost". If you get some air when you run the fan, where does it seem to be coming from most strongly?

 

Thanks. I was just trying to eliminate one thing at a time.
Still,if you don't mind sending that picture I would appreciate it.
Thanks again.

 

I'll need to go back and look at it some more. I will be back after I look for vacuum leaks and more info on where the air is actually coming from.
Thanks again.

 

Ok, why did I think you had a 95... the 98 never had a HCV so there's no vacuum line.

I took pictures, but they're not relevant in your case.

The vacuum stuff and blend door however IS. There is a vacuum line that comes out of the firewall on the passenger side that taps into the vacuum line running to the reservoir (along the firewall and fender). The 98 controls should be the picture controls showing the air direction. Default is still "defrost". If you can't hear any shifting of stuff when you change the setting, it's vacuum related. If it's just the air temp (meaning flow is ok, but no heat) it's blend door related.

 

Ok, heat problem solved. I had it air locked.
Now I guess to find why the air is not directed correctly. The blend doors maybe.
I did watch a youtube video once showing someone digging through the plastic wall beside the glove box to get to them.
Has anyone here tried that?
Taking the entire dash off seems a really daunting task.

 

I have not pulled the dash apart.

If the air direction (meaning only WHERE it is routed to - upper vents, lower vents, windshield, etc) is incorrect, then it's a problem in the vacuum controlled system, usually a vacuum leak.
If the mix between heated and not-heated air is incorrect, it's an issue with the blend door. Typically this is either a problem with the blend door motor or the seals have disintegrated.

Pulling the dash is time consuming, but reportedly not difficult. Folks generally advise carefully photographing stuff before disassembly and carefully labeling parts as you remove them.
I'd also caution to be careful around the passenger side airbag - make sure you disconnect the battery prior to work and follow all safety rules and you'll be fine.

 

There! I fixed it for ya!

 

Why thank you sir!

 

Yes indeed.Thank you. I was out of town yesterday and missed the chance.