Owner`s manual

OPERATION — PAGE 13WILLIS POWER SYSTEMS
Standard Integrated System
This system integrates the APU into the coolant ow of the truck
engine, allowing the APU to heat the coolant as it circulates through
your truck engine to prevent cold starts.
The sleeper heater core of the truck engine accesses the heated
coolant which keeps the sleeper heater core warm for a few hours.
If you were to run your sleeper heater blowers on, you can take
advantage of this heat for approximately 6 to 8 hours.
Tips for increasing heat with a Standard Integrated System:
• Start your APU, and then turn the truck key to the “On” position
to power the truck blowers.
• If you need additional heat, you can close the valve located on
your truck’s thermostat housing block. See image below.
WARNING: This is not recommended because if you forget to turn the valves
back on in summer temperatures, your APU can overheat.
• During unusually cold temperatures, the truck’s engine will absorb
a large amount of heat from the coolant ow before reaching
your heater core & blowers. Under these circumstances, you may
have to restart your truck engine for additional heat.
WARNING: The thermostat housing valve must be open during warm weather.
If the valve closed during the summer, it may cause your unit to shut down.