COOLING SYSTEM
□
Heater system too restrictive - core, plumbing size, bends, shutoff valves, length of
circuitry, etc.
□
Parallel circuitry with multiple cores
□
Boost pump required, defective, not turned on
□
Air in heater circuit and coolant
□
Solder bloom, silicate dropout, dirt, debris, etc.
□
Shutoff valves not fully opened
□
Fuel heater in circuit
2. Check coolant-side cause, reduced heat transfer capabilities, by investigating the
following:
□
Improper concentration or grade of antifreeze and inhibitors
□
Undersized heater core(s)
□
Heater plumbing not insulated
□
Low ef
fi
ciency cores
□
Contamination of core tube surfaces, deposits, etc.
□
Fuel heaters plumbed in cab heater circuit
3. Check the following air-side causes:
□
Low ef
fi
ciency cores
□
Improper air
fl
ow
□
Excess outside air through core
□
Core
fi
ns separated from tubes
□
Core surface contamination, dirt, debris, oil
fi
lm, etc.
□
Leaking air ducts
□
Malfunctioning air
fl
ow control valves
□
Undersized heater cores
□
Poor distribution system
Cab interior should be completely sealed to eliminate direct cold air source, in order to conserve
available heat energy. Heat loss to outside can be minimized by using thermo windows, reducing
exposed metal surfaces, increasing insulation usage, etc.
7-56
All information subject to change without notice.
(Rev. 03/06)
7SA250 0603
Copyright © 2006 DETROIT DIESEL CORPORATION