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Mark, 22 Year Factory trained technician
Category: Jeep
Satisfied Customers: 11332
Experience:  Jeep factory training........25 years in the industry.
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1997 Jeep Grand Cherokee: litre..heater core hoses

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1997 Jeep Grand Cherokee 5.2 litre. No heat! Both heater core hoses are hot and heater core is not pluged. What can be the problem?
Welcome to Just Answer Jeep my name is Mark.

What procedure did you use to check the blend door?

Is this the automatic temp control system......or the manual?
Customer: replied 6 years ago.
I took the blender door motor off the HVAC unit and turn the door manually. There was hardly any difference in temperature! The temperature control unit is manual.
Ok, so if manually moving the door didn't change anything then there isn't enough heat getting to the heater box.

If you are happy that both heater hoses are HOT.......and equal temperature.........then there has to be a restriction in the core itself.
Customer: replied 6 years ago.
So what you are saying is that there is a restriction in the heater core itself. I even took off both heater core hoses and ran water through there and it came out crystral clear! No blockage at all!
Alright so you sound convinced the core is ok and in that case it would only leave an air flow restriction inside the heater box. There may be a broken door impeding the desired airflow.
Customer: replied 6 years ago.
So the only way to see that is to take the dash apart, and remove the HVAC and take the HVAC apart and see whats going on?
Before you do that I would try removing the blower motor and see if there is any sign of broken plastic pieces inside the box. Once the motor is removed, reach up inside the box and feel around for any potential debris that might be in the box and you may also be able to reach up to the recirculation door and get an idea if it feels broken or not.

It's also not unusual to find rodents building a nest inside these boxes and this would certainly block airflow through the box.

Otherwise, it comes down to process of elimination. If you are convinced the core is getting hot, then the problem has to be inside the box and yes, it would have to come out and be disassembled.
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