I've been working on my 88 xj6 and have some questions. The heater hasn't worked since I got the car. I'm pretty sure I need to flush the heater core. My first questions is it possible to flush the core while it is still in the car? It just looks so deep in there and it would be take a whole weekend just to get too.

My other question is about the operation of the unit. No matter what settings I put the system on, it is always blowing air out of the defrost vent. It will still blow out of the dash vents but it's always blowing out of the defrost. Is that the way these units operate? I would really like to know before I start to tear everything out just to get to the vacuum lines.

Any help would be appreciated.

 

Red:
... apparently not a lot of experience on this issue around here! And alas, I cannot contribute anything except to suggest that you the XJ40 e-book from Jag lovers might uncover some wisdom. There is a quick link from the XJ40 FAQ "sticky" section of this forum. The blower motors and flaps tend to wear out over time and can sometimes require a fair amount of work to dig out of the dash and overhaul.
Best of luck!
Scott