Operating instructions

C: Auxiliary Bunk Heat Exchanger Kit 905.670
Sleepers with continuous fan operation or high amperage heat exchanger fans.
1. Position the auxiliary heat exchanger in a suitable location under the bed, toolbox or other space
and secure as required.
2. Plumb coolant lines to the heat exchanger as shown in “C: Plumbing with Auxiliary Heat
Exchanger Kit P.N. 905.670” figure 410.
3. Make air duct connection at heat exchanger and route ducting into the sleeper.
4. Install Webasto thermostat #129.560. Locate the thermostat in an area where routing of the wiring
is possible, about halfwaybetween the ceiling and bed. Do not locate in direct air flow from the
heat exchanger or mount to a cold surface.
5. Mount interlock relay near the heat exchanger.
6. Route one leg of the included blower interface harness from the relay to the Webasto heater and
the other leg to the thermostat and secure every 12 inches (30 centimeters).
7. Make wiring connections as shown in figure 422, sleeper fan wiring and figure 423, wiring diagram
Thermo 90 S.
Fig. 422: Sleeper Fan Wiring Using Interlock Harness P.N. 905.663
430
4 Installation Thermo 90 S