I have searched all threads dealing with this problem. I have a 1999 Jeep Cherokee (not grand) 4.0? 4 wheel drive. Online, some folks said I should do the following: 1. Your coolant level is low
2. Your thermostat doesn't close and needs to be replaced
3. The valve from the cooling system to the heater core is stuck
4. Your heater core is clogged


So where is the valve located to the heater core?
Your alls help would be appreciated.
j

 

No heater control valve, have you ever done any maintenance to this vehicle?

 

Then what is the box next to the heater core on the firewall?

 

You didn't mention box, you posted:
3. The valve from the cooling system to the heater core is stuck


Your vehicle still doesn't have one.
So what about the maintenance?

 

We haven't done any maintance on the Jeep yet. We purchased this Jeep last yr. The heater worked fine from Nov 2011 to March 2012 of this yr. there has to be a valve that allows the warm coolant to flow thru the heater core for heat and to stop it for cooling

 

Nope. It is controlled by the the blend door. You don't have a heater control valve. If I am not mistaken the manufacturer stopped putting them in in 96. You need to try to flush the heater core really well in both directions. Hopefully that will take care of the lack of heat.