I have already read dozens of posts and tried everything I know of to fix my problem and it still persists. The heat in my 2000 XJ can only keep the cab warm if it is above 35-40F outside, any colder and the air is luke warm at best. The blower works fine, the engine gets up to temp properly, t-stat is new and the entire system has been flushed and coolant looks brand new. The heater core is not blocked.

Inside the cab I have verified the blend door actuator is functioning but I removed it to operate the blend door by hand. Even with the blend door completely closed by hand, the heat was only warm after 20 minutes of driving in 45 degree weather. The blend door does not seem to be broken, it swings back and forth with little effort and makes solid contact when opening and closing.

It might be worth noting the air may be warmer when coming out of the upper vents, compared to the floor vents. Also a minimal amount of heat does escape from the defrost vents.

I would really appreciate any insight as to what I could be missing. Thanks!

 

Bump. It got nice and warm yesterday, but the outside temp was about 50 degrees.

 

I blew out my heater core several times both ways and it now heats as needed. We used a bucket with an air hose that sucks up water and just kept the water running both ways. I was surprised as the junk that came out od the core.
Ranger Rick

 

i dont know..
i have a 98 and a 2000. i spent an hour flushing back and forth thru the 98 core last year. it started dirty then got clean. i kept it up.
it never makes real heat!!
the 2000, in 30 deg weather, in 4 miles if i put my fingers on the duct it burns!! too hot. ive done nothing to the 2000.???
i think the core gets plugged and passes water thru just a small part,,,just a guess. like in and out , not thru it all.

 

I don't know if the 2000 models had cabin air filters or not but here what caused my problems.

 

that looks like a rats nest to me

 

yea. Probably is. But it caused me problems and I didn't find out about it till I removed the HVAC box. Just a suggestion.

 

OP,


You can pull the blower resistor block out to see if there's nesting material in the blower chamber. Or roll the glove box down and look through the recirc air door opening to see if there crap in there.


View of the resistor block full of goodies.





View of the blower fan with the recirc air door open.



.

 

Ken, where is that box located to pull out?

 

Heater core has been flushed both ways with water and air, plus a cooling system flush solution cycled through it for a while. Can there be deposits in the core that cause poor conduction without blocking flow?

I replaced the blower resistor after I bought it because it had failed and melted the connector. The motor seems to be working fine on all 4 speeds.

I will look into that recirc air door, that is one thing I haven't found or researched yet.