Thermo King T-1080S, Maintenance Manual

Page: 99 / 191

Engine Maintenance
98
Vacuum Fill Procedure
See “Vacuum Fill Procedure” earlier in this
manual.
Engine Thermostat
For the best engine operation, use a 160 F (71 C)
thermostat year round.
Coolant Level Switch for Units with
Coolant Expansion Tank Only
(Ending 10/16)
The coolant expansion tank uses a magnetic float
type coolant level switch. When the coolant level
is at or above the switch, the float is in the upper
position and the switch is closed. When the
coolant level is below the switch, the float is in the
lower position and the switch is open.
Testing the Coolant Level Switch
You can test the switch in the unit by adjusting the
coolant level. You can also remove the coolant
level switch from the expansion tank and test the
switch by moving the float up and down.
1. Remove the wire harness connector from the
coolant level switch.
2. Use an ohmmeter to check the continuity of
the switch at the connection pins.
3. Make sure the coolant level is above the
switch and check the continuity of the switch.
The switch should be closed. If you removed
the switch from the tank, do this check with
the float in the upper position.
4. Drain coolant from the expansion tank until
the coolant level is well below the switch and
check continuity of the switch. The switch
should be open. If you removed the switch
from the tank, do this check with the float in
the lower position.
5. Replace the switch if it is not closed in step 3
and does not open in step 4.
Replacing the Coolant Level Switch
1. Disconnect the wire harness connector from
the coolant level switch.
2. Drain coolant from the expansion tank until
the coolant level is well below the switch.
3. Remove (unscrew) the coolant level switch
from the expansion tank.
4. Install the new coolant level switch and
position the orientation mark down as shown
in the following drawing.
1. Thermostat Housing
2. Gasket
3. Thermostat
4. Gasket
5. Water Pump
Figure 178: Water Pump Assembly and Thermostat
1
2
3
4
5
1. Float in Upper Position - Switch Closed
2. Float in Lower Position - Switch Open
Figure 179: Coolant Level Switch
1
2