Hi all.
My 1992 XJ is blowing good air but cannot blow heat.
After running for awhile, the heat guage reads proper heat
levels but the heater inside is blowing cold.
Any suggestions? Thanks.

 

ive actually had the same problem, for the last 3 years, lol so im listening as well.

 

check to see if the two heater hoses are getting hot going to the heater core thay run along the pass side of the valve cove .
if only one gets hot than you need a heater core
now if both are cool then chack your thermostat.
i also found one that had no heat but the eng temp was good and i found
3 out of the five impellers were broken off.it was giving enuff flow to cool the eng but not to flow through the heater core.
also see if you can hear the blend door closing when you move the **** in both directions.

 

. . . . .

 

Drove the XJ tonight and the heater works again.
What the ...Oh well. If it ain't broke now I won't fix it.

 

there is a vacume controled heater valve in the engine compartment that can gum up and not send the hot collant to the heater core if it happens again get it to opperating temp and have some one switch it from cold to hot and wach the valve to see if the diagram is moving. you will see the rod move in when they switch it back it will move back out, it is set up to byepass the hot water back to the radiator.