Proheat X45–School Bus - Manual (Page 73)

PROHEAT INSTALLATION & SERVICE 5-16
A COOLANT FLOW diagnostic code is displayed when the coolant temperature
reaches 185˚F (85˚C) in less than one minute after ignition. This indicates
that the coolant flow is severely restricted or blocked. This feature aids in
detecting coolant flow problems that can degrade the PROHEAT performance.
An in-line flow indicator is a valuable troubleshooting tool used to: (Figure 5-15)
a) Check the coolant flow and direction.
b) Check for air in the system.
c) Check for restrictions caused by the truck systems
ie. Shuttle valves, manual valves, air operated valves.
Check: Coolant Flow
a) Coolant Lines: For restrictions and blockages
Are clamps tight?
b) Shut-off Valves: Ensure that shut-off valves are open and
functioning properly.
c) Fittings: Fittings must be at least 1 ⁄
2
" NPT or larger.
Avoid using 90˚ fittings where possible.
d) Coolant Flow Direction: The PROHEAT must be plumbed so
that the coolant pump is pumping the coolant in the same
direction as the engine coolant pump. The PROHEAT can be
used when the engine is running.
e) Coolant Pump: Does the pump function properly? (page 5-27)
f) Coolant System Capacity: The coolant system must contain
at least 3 gallons (11 litres) of coolant. If the system
contains less the coolant may reach 185°F in less than 1
minute causing a COOLANT FLOW diagnostic code.
g) Sleeper Heater: Many OEM sleeper heaters are combined
with an air conditioning system. The solenoid shut-off valve
used to cut off coolant flow during the air conditioning mode,
must be open when using the PROHEAT. (Refer to page 3-9.)
Figure 5-15 Flow Indicator – TK9002
SLEEPER FAN
OTHER POSSIBLE
LOCATIONS
FLOW
INDICATOR
3 Coolant
Flow
NOTICE
If the coolant system is contaminated
with magnetic material, it may cause
the impeller to stop turning.