Service manual

— Page 34 —
© January 2013 Aqua-Hot
®
600-D01 Series Hydronic Heating System Service Manual - Rev. A
SECTION 4: AQUA-HOT COMPONENTS
Pumps
Engine Preheat Pump:
The Engine Preheat circulation pump draws the cold anti-
freeze and water heating solution from the motor home’s
engine and then propels it through the Engine Preheat Heat
exchanger, located inside the boiler tank.
Troubleshoot the Engine Preheat Pump if the following con-
dition has occurred:

The Engine Preheat Pump is not operating, and the
Engine Preheat Switch on the Switch Panel inside the
motor Home is in the ON position and the “Low Temp
Cutoff Status” indicator light is illuminated on the
electronic controller.

The Engine Preheat Pump indicator light illuminates red
on the electronic controller.
Troubleshooting:

The Engine Preheat Pump is not operating, and the
Engine Preheat Switch on the Switch Panel inside
the motor Home is in the ON position and the “Low
Temp Cutoff Status” indicator light is illuminated
on the electronic controller.
1.
Verify that the “Low Temp Cutoff Status” indicator
light on the electronic controller is illuminated, as it will
be continuously with the 600 Series Aqua-Hot.
2. Verify that the Engine Preheat Switch is in the ON posi-
tion, on the interior switch panel inside the motor home.
Either the diesel burner switch or the electric element
switch must also be activated in order for the engine
preheat feature to function.
3. On the electronic controller, verify that the engine
preheat pump light is illuminated.
If the Engine preheat pump indicator light does not illu-
minate, complete the following:
A.
Verify that the low temperature cutoff light and the
diesel burner/electric heating element status lights
are illuminated on the electronic controller.
B. Using a jumper wire, bypass the engine preheat
switch on the JP2 plug, by connecting pins
Preheat-O and Preheat-I together.
If the engine preheat pump indicator light illuminates
with the jumper installed, inspect for loose wires. If no
loose wires are found, replace the engine preheat switch,
on the interior switch panel, inside the motor home.
If the engine preheat pump indicator light does not
illuminate, and the Low Temperature Cut-Off Light is
illuminated along with either the diesel or the electric
element status indicator light, follow the instructions in
this manual to replace the electronic controller.

The Engine Preheat Pump indicator light illuminates
green on the electronic controller but the pump is not
running.
A.
Using a voltmeter, check for 12 volts of DC power
on the JP3 plug pins corresponding to the pump not
operating.
If 12 volts of DC power are not present, follow the
instructions in this manual to replace the electronic
controller.
B.
Disconnect the engine preheat circulation pump’s
wires from the wiring harness, then, using a voltme-
ter, check the wires on the wiring harness for 12
volts of DC power.
If 12 volts of DC power are present at the wiring
harness, follow the instructions in this section to
replace the engine preheat circulation pump.
NOTE: The engine preheat circulation pump can be tested
by connecting it to an external 12 Volt-DC source to verify
that the pump is defective.
NOTE: Either the diesel-burner switch or the electric ele-
ment switch must also be activated in order for the engine
preheat feature to function.