I had the same problem that turned out to be the Heater core leaking. Check the floor on the passanger side to see if the carpet is wet. This is a big, expensive job. The dash has to be removed to get at the heater core. Plus, you also have to deal with the AC evaporator, etc. Might want to consider trading it in and let the dealer have the problem.
The PCM is located on the firewall behind the coolant reservoir on the passenger side of the vehicle. Most notably are 3 large connectors.
The coolant temperature sensor on a 2001 Jeep Cherokee is located in the intake manifold. It monitors the flow and temperature of coolant through the engine.
Low coolant or bad sensor
If you completely filled the cooling system and reservoir when changing the coolant, some will be forced out of the reservoir overflow when the engine gets hot and the coolant expands. If you suspect that there is a leak in the system, run the engine until it reaches operating temperature, and then shut it off. Observe all hoses and connections carefully after engine stops, as this is the period of highest pressure on the cooling system.
A cracked head could be the cause of the problem. This, along with a cracked head gasket would allow engine coolant to enter the oil supply. Coolant and oil do not mix well and over time, the oil looses its capability to lubricate. Check your oil for white spots and check your coolant reservoir for oil residue.
Junkyard...........oops........recycle yard
The radiator cap could be the cause of coolant reservoir overflow or backup. Have the cap checked to see if it is bad.
In the coolant reservoir up by the firewall.
it is normal, when the coolant is hot and pressure built, the pressure cap allows the coolant to drain to reservoir to reduce pressure in the cooling system But, if it continually does this whereby the reservoir overflows and the vehicle overheats due to a lack of coolant actually in the radiator when cool, there may be an overheating problem or blown head gasket on the engine.
Yes, the coolant reservoir should be sealed properly to maintain the system's pressure and prevent coolant from evaporating or leaking. A sealed reservoir also helps ensure that the coolant can effectively circulate through the engine and absorb heat. If the reservoir is not sealed, it can lead to overheating and potential engine damage due to the loss of coolant and pressure. Regularly check the cap and the reservoir for any signs of wear or damage.
The radiator does not have a cap, instead, the coolant system reservoir is also pressurized and the pressure cap is on the reservoir.
could have a crack in it that is leaking under pressure
There is not a radiator cap, there is a coolant reservoir and it has a plastic cap that controls the pressure in the coolant circuit.
On a 1998 Lincoln Continental : The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap . The engine coolant reservoir is in your engine compartment , towards the passenger side of the engine compartment
It is on the passenger side of the engine compartment right in front of the coolant reservoir. The shiny long refrigerant line has the port covered with a screw off cap.
The thread on cap for your engine coolant reservoir is the pressure cap / radiator cap ( the engine coolant reservoir is located on the drivers side of the engine compartment , near the firewall )
the water pump is right behind the radiator and is belt driven. Also try to check the coolant reservoir by having it pressure tested