I have been looking in to this for awhile and i have to say that you guys have been great help. I have done every trick you guys have suggested, I changed thermostat and blower resistor, flushed and back flushed the heater core with a cleaner. still very weak heat, but if i put it in recirc mode i get good heat as soon as i go to the defroster cold air. If it is a more mid day i get ok heat but not great. The only thing i can think of is to much air flow. Does the cowl under the wper effect this ? mine broke up when the hood latch failed. any suggestions would be a great help thanks in advance

 

What year is your XJ? Are you sure it's a XJ? Where are you located?

Are you saying air only blows out the defrost? Does your fan blow at the different speeds?

 

It is a 98 it blows on all fan setting but no heat unless it is on recirc if i put it on defrost it blows cold i am in upstate ny

 

Any help on this ?

 

Did you check the blower motor relay as well? Wouldn't hurt to replace. Fairly cheap. It's hidden behind the glove box by the resistor. Lastly, have you checked the climate control switches? Sound like that's your issue if it's blowing hot in other settings. You're likely going to have to chase potential vacuum issues, it could be a vac switch problem. Pick up a repair manual for the diagrams.