1997 heater issues

[Gianni]

So trying to figure out my heater issues on my 1997,

I've noticed it's always blowing hot air, even with fan off, when I turn fan on, it won't send cool air only hot, and it will only come out of the demister and side vents even if I change it to say feet for example.

I've read that it all runs off vac lines, has anyone had this issue before, what's the fix?

I'd take dash apart and look myself, but with steering wheel airbag and dash airbag I'm not sure how that's done without it going kaboom :p

[Sifter]

The default setting if one of the vacuum lines comes off is defrost for safety reasons - sounds like that is what yours is doing....

Check your vacuum lines are functioning...

[Gianni]

My vac lines from engine to firewall are fine. But I'm not sure about checking under dash, with the airbag and all

Also would that stop me switching between vents, feet, defrost ect

[wes]

Has it always been like this?

My money is on vacuum lines.
If you stick your head in the drivers footwell and look up under the dash towards the front of the centre console, you will see one end of the heater box.
On the 97s there are 3 round silver 'canisters' at that end - each with colour coded vacuum lines attached.
One has a red line, one has a brown line and the third has 2 lines - blue and yellow attached.
I'd make sure all the vacuum lines are still attached to the nipples on the silver 'canisters' (sorry, dunno what they are called). But the vacuum lines just push on.

You could probably have a look behind your HVAC panel too.
You need to unclip the long vent at the top of the dash - slide a screw driver along the vent and gently lever up - there's only a few clips holding it on.
Once the long vent piece is off, you will see 2 screws holding the middle dash cover in place - undo those.
Then pull out the ashtray - on the early models, there's another screw behind the ashtray - then the middle dash panel will pull straight off - there's only clips holding it on once the 3 screws are undone.
You can then unscrew the 4 screws on the HVAC control panel and have a look behind it.
There will be a 'harness' plugged in with all the coloured vacuum lines - don't be scared to unplug it and check it out - it's unlikely but maybe it's not plugged in properly.
The vacuum 'harness' has another connection further down the line but I can't remember how easy it is to get to with the dash in place but that would be good to check as well - might be able to get to the second connection if you take the glove box out.
While the HVAC control panel is out, satisfy yourself that the slider temp control is working OK - make sure the cable is still attached at the back and that it still has full range of movement - does it still feel like it is moving the blend door in the heater box?

EDIT - It's unlikely the vacuum lines would detach from the silver 'canisters' under the dash but it's worth having a look just to eliminate one possibility. But it definitely sounds like a vacuum line problem.

[wes]

The silver 'canisters' I referred to in the previous post are called 'vacuum actuators' and for TJs with aircon, there's another one at the other end of the heater box.
In the passenger footwell, undo 3 screws holding the protective plastic 'kick panel' on the bottom of the heater box.
This will reveal the other vacuum actuator which should also have a vacuum line attached.

[Jonny Jeep]

On a 97 the heat control slider connects with a cable. It may have come off. Mine did once. I can't remember if you need to remove the center dash trim to get to it. online FSM are in my sig which may help. Should be a heating and air conditioning section. If you can't switch between vents that's either a vacuum problem or broken arms on the end of the vacuum actuator arms. You'll need to get you're head in the footwell to check the vacuum actuators move when the vent control is slid, and to see if the arms are intact or broken too.

[Gianni]

Looked at all vac line under drivers side and behind controller. One of the black ones was pulled out. Looks like there are a few spots it can go on. Which one? I've tried ten all but still no difference with vents.

I noticed the leaved under passenger side for hot and cold, the cable is gone. Gotta find it. He he