Ok I just bought my 98 xj classic a few days ago and I've been too busy to do any poking around so my apologies in advance.
Heater blows cold, ok might be plugged core.
Only blows out of the floor. No vents and no defrost. I can hear it switch ducting when changed from floor to vent but it's not coming out anywhere. The sound is like the air is forcing itself behind the dash or something.
Does this sound like a combo of problems?
Engine temps steady around 210.
Vehicle speed doesn't affect problem.
I'll have a little time this afternoon to check the HC and fluid levels. What should I check after those?
Searched for awhile but nothing came up with my exact symptoms. Thanks for any info or help.

 

Sounds like maybe your blend motor is toast.

To confirm a decent heater core you can feel the hoses to and from the core. If they are really different temps, its most likely clogged.

 

Man I hope it's the motor and not internal. Like the stop point or something.

 

there are deff a few things... bad vac. lines will cause weirdness like changing which vents the air flows from, a bad, or clogged heater core will limit or not allow hot air... idk...

 

Update. Took a ride to the gas station and vents worked still not hot. Maybe a little warmer than cold. Still wouldn't defrost but floor worked. Get gas and head home. Only floor works again and same cold temp.

 

Ok so the blend motor is cable driven and seems to be working. You can hear it close the door. Coolant was pretty low, it took almost a gallon. The temp is definitely warmer now but still not hot. The ducting options seem intermittent. Now defrost does blow. Heater core will need a flush. The lower hose is cooler to the touch.
Still at a loss as to why the duct options are intermittent.
Any suggestions?

 

When you go to switch vents, does anything happen? You said blend door is cable operated, are the vents operated the same way or vacuum related?

If they are vacuum actuated, it could be bad vacuum lines or something. If not, bad cables.

Or, less likely, somehow there is a clog of sorts in your vents.

 

I'm guessing it's vacuum now. Just got find the leak/leaks.
When I switch vents sometimes they change, sometimes they don't. When the forward facing vents don't work it gets loud like there's a blockage and the air is blowing from the small vents on either side that blow on the windows. The floor seems to always work. When the defrost doesn't work it seems to stay on the floor.
Maybe a bad switch.