Table of Contents
Advertisement
GENERAL
To aid in cold weather starting, the truck can be
equipped with cooling system heaters. Two high
capacity coolant heating units are mounted under the
engine on the power module subframe. The system
includes:
• Heaters
• Thermostats
• Coolant Shutoff Valves and Hoses
• 220 volt Receptacle
• Power Cables, Thermostat Wiring, and Junction
Box
Heater operation is controlled by a thermostat
mounted on the intake end of the heating units. The
thermostat turns the heater ON at 48°C (120°F) and
OFF at 60°C (140°F). Shutoff valves allow heater
element or thermostat sensor replacement without
loss of engine coolant.
Do not operate engine while the cooling system
heater is plugged in. The flow check valve elimi-
nates coolant flow through the heater while the
engine is running. This will cause a lack of circu-
lation in the heater and burn out the heating ele-
ments.
Maintenance
To check for operation of the heating units, the outlet
water hoses should feel warm to the touch.
1. Check all electrical connections to insure proper
connections are made.
2. Check for a burned out heating element. (Do
not remove heating unit from the truck.)
a. Remove the two Phillips head screws and
slide end cover out of the way.
b. Connect a voltmeter at the two electrical ter-
minals and check for operating voltage (220
to 230 volts) while coolant temperature is
below 48°C (120°F). If correct voltage is
present, the heating element is defective and
should be replaced.
3. If correct voltage (measured above) is not read
at heating element terminals, the thermostat is
defective and should be replaced.
M07012
ENGINE COOLANT HEATER
HEATING ELEMENT
Removal
Engine Coolant Heater
1. Disconnect the external power source at the
plug-in receptacle.
2. Close the shut-off valves located at the inlet and
outlet ports.
3. Remove heating element.
a. Remove the two Phillips head screws from
cover at power cable entry. Slide cover out of
the way.
b. Disconnect the two electrical leads and
remove heating element from the cartridge.
FIGURE 7-1. COOLANT HEATER
1. Thermostat
2. Heater Assembly
3. Water Outlet Port
4. Heating Element
5. Cover
6. Terminals
M7-3
Advertisement
Chapters
Table of Contents
