2000 4.0 S-type. Did some engine work with the engine outside the car, and now I don't know why I have no hot air. Sometimes it can get about lukewarm, but then it goes away. I've tried bleeding the system the way JTIS says, and I get no pressure from the bleeder. Maybe a very slight drip for 2-3 seconds, and then nothing.

The 3 lines all going to the heater core all get hot. The aux water pump is working. The blend door inside the cabin is working. The A/C works and blows cold air. When I choose full hot on the climate control, I don't get any heat.

What else can I look at? Anything I'm doing wrong?

 

sounds like an airlock to me, are you letting it get to temp ? also try it on an angle as ive read this can help

 

Car gets up to temp pretty quickly; and doesn't overheat. I did try the angle trick, to no avail. I'm about to drain the whole system and start over.

 

Have you tried flushing the heater core?

 

What's the procedure for that?