thouse

So I have a 1991 Jeep Cherokee Larado and my heater is giving me some problems. It does not put out heat when it warms up only after I get going and then sometimes when it's on it will start blowing cold air and then switch back to hot. Along with this problem my heat temp gage is almost always maxed out or saying I am running at 210 degrees. Other than the heat everything else runs great and it drives fine. Any suggestions as to what might be wrong?

freegdr

check this heater control valve for operation when you have the heat selected it by the pressure bottle

freegdr

look like thic check for vacuum in small line whn running

freegdr

when heat stops see if tis coming out of defrost vent

thouse

thank you very much I'll try that

thouse

i tried that it was all cold air

freegdr

check the vacuum ball for hole and check the lines for cracks and loose connection, you dont have to take the bumper off look in pass fender well

thouse

I'll try that to thanks

corbinxj

Have you done a complete cooling/heating system flush?

thouse

Last year my bottom radiator hose broke do to ice in the hose it was flushed then

fishman435

I have the same problem. It blows cold until I get going or rev the engine. I have changed the waterpump,thermostat,flushed the system,flushed the heater core,new radiator cap,and I removed the bypass valve and now I'm scratchin my head.