PAD 8D7898 - Caterpillar

Possible Cause 5
There is a failure with the device for the heater control.
Determine the type of controlling device that is used on the machine.
If there is a water valve that is present, continue to Step 3.
Inspect the water valve for any signs of damage.
Check the water valve making sure that the valve opens completely when the temperature control knob is set to maximum heat.
If the water valve fails to open or the water valve fails to close, move to "Possible Cause 6".Possible Cause 6
There is a failure with the cable for the water valve or the potentiometer.
Determine the type of control for the water valve that is being used on the machine.
If the machine has a built-in potentiometer, continue to Step 3.
Check the machine to make sure that the potentiometer is attached to the wire harness within the dash of the cab.
Check the water valve making sure that the valve opens completely when the temperature control knob is moved to maximum heat.Symptom: The heat that is within the cab is uncontrollable.
Possible Cause 1
The water valve is installed incorrectly or backward.
If the machine is equipped with a water valve control, check the valve making sure that the valve is installed properly.
Some water valves are manufactured so that there is an arrow that shows the flow direction on the side of the valve body. Make sure that the arrow is pointed toward the line that leads to the heater coil.
If the machine is equipped with an electronically driven water valve, make sure that the actuator is attached securely to the water valve.Possible Cause 2
There is an electrical failure with the control panel.
Inspect the control panel to make sure that the control panel is receiving power when the machine is turned on.
Check to make sure that the wire harness is connected to the control panel.Possible Cause 3
There is a failure with the potentiometer.
Check to make sure that the potentiometer is attached to the wire harness within the dash of the cab.
Check to make sure that the water valve opens completely when the temperature control knob is moved to the position of maximum heat.Symptom: There is a coolant smell that is present within the cab.
Possible Cause 1
There is a leak that is present at the hose or the hose clamps.
Inspect the connections between the heater coil and the heater hoses.
Check the hoses for cuts.
Check to make sure that the hose clamps are tightened to the proper torques that are shown on the dimension drawings.Possible Cause 2
There is a leak that is present at the heater coil.
Inspect the heater coil to determine if there are any visible cracks or holes in the tubing.
Check to make sure that the hose clamps are tightened to the proper torques.Possible Cause 3
There is a leak that is present at the water valve.
Inspect the water valve for any damage.
Check to make sure that the hose clamps are tightened to the proper torques.
If the water valve passes both these initial tests, refer to the Troubleshooting, UENR4125, "Machine Preparation For