heater help

i can hardly drive my xj because the heater bearley gets hot enough to heat the cab, after i drive for like 15 minutes. It will worm up just a lightl bit what could this be. thanks

What does your temperature gauge say ? Are the hoses hot after 15 minutes, if not it could be a stuck thermostat in the simplest case or a plugged heater core in the worst case. Also seen worn water pumps do the same thing, they don't move enough coolant to push it thru the heater hoses.

i will check it out and post later but the the gauge is normal once its worm up thanks

Plugged heater core is a definite possibility, but a couple of other possibilities for starters. One is that the heater valve is not operating properly. This is a vacuum controlled valve, under the hood. You can see it easily if you trace the hoses. Check to make sure it's opening all the way. Also, do make sure your coolant level is sufficient. When it goes low it will often be enough to cool the engine, but the heater won't work.

Also, if you're a frequent reader of this forum you'll probably already know that vacuum problems can cause the heater to default to defrost, so when you seem to be suffering from the cold, make sure there isn't a bunch of heat coming out the defrost vents when you don't want it there.

i was just cheking it out, and the presure bottle lines are all ok, but it the colent level is low when the motor is running its not up to the second hose should i add some. Also how do i see if the valve is working that you speek of thanks

The vacuum controlled valve linkage will actually move to open or close the valve when you operate the control or remove the vacuum hose. Once it's open, heater core blockage or insufficient flow affects heat output.
Also check the heater flap door is operating inside the heater box and allowing hot air to circulate.