First of all, hey everyone! I've been lurking on here for awhile, but this is my first post.

Anyway, I have pretty warm heat out of the two drivers side vents but it's considerable colder out of the passenger side. I wouldn't think it'd be a thermostat or heater core since I'm getting good heat in 2/4 vents, but I don't know. Any ideas? This is on a 98 XJ with an I6. Thanks!

George

vac lines, HC might be partially blocked, there is something called a blend door (not the technical name for it) that controls the flow of air to vents... other than that, idk...

I think the blend door just switches from hot to cold, which shouldn't be causing the issue if he's got good heat on one side.

Does any air move at all out of the "colder" side?

The air moves ok out of the passenger side, just noticeable colder air.