FORM NO. 56043123 - SR 1900 -
11
TO TROUBLESHOOT THE HEATER TEMPERATURE CONTROL
Service Tip:
If you have to replace the Heater Temperature Control in the cab, we recommend that you do so as follows:
Remove the Overhead Control Plate from the cab.
1.
Disassemble the Heater Temperature Control from the Overhead Control Plate.
2.
Cut the seven wires going to the Heater Temperature Control at the point where they enter the sealed back of the module.
3.
Check the continuity of the
fi
ve wires going to the Valve Assembly (VIO, WHT, GRN, GRA/BLK WHT, and ORN).
4.
If there is continuity in all
fi
ve wires from the cab to the Valve Assembly, continue to step 5.
If there is no continuity in any of the
fi
ve wires from the cab to the Valve Assembly, you will need to either repair the wires or run new wires to the Valve
Assembly.
Install the replacement Heater Temperature Control on the Overhead Control Plate.
5.
Splice the original wires from the Valve Assembly to the replacement Heater Temperature Control using butt connectors and heat-shrink insulation.
6.
Reinstall the Overhead Control Plate in the cab.
7.
Yes
Is there 12V to the Heater
Temperature Control (BLK and
RED wires)?
Is there approxi/- 9.75V
at the Valve Assembly
Connector (BLK/WHT and
ORN wires) when the Heater
Temperature Control
E1
is
rotated between cold and hot?
Check the wiring to the Heater
Temperature Control and repair
as necessary.
There is no Cab heat/the Cab
heat cannot be controlled.
Is there continuity in the three
feedback pot wires (WHT, VIO and
GRN) from the Heater Temperature
Control to the Valve Assembly
Connector?
Replace the Heater
Temperature Control.
No
No
No
Yes
Is there continuity in all five
wires from the Heater
Temperature Control to the Valve
Assembly Connector?
Yes
No
Repair the wiring
as necessary.
Replace the Heater
Temperature Control.
Repair the wiring
as necessary.
Yes