General Troubleshooting
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 94
Lack of Interior Heat
A lack of interior heat with a functioning burner can be
attributed to many potential issues in the Aqua-Hot. Diagnosis
will involve three stages. Stage 1 will outline common reasons
for overall unit non-function that exists outside of the unit.
Stage 2 will diagnose common issues inside the unit, including
lack of burner operation. Stage 3 will address specific reasons
for a lack of interior heat.
It is very important that troubleshooting proceed in the order
outlined below. The issues most common with a lack of heat
are:
• A non-functional three-way valve
• A seized circulation pump
• Air trapped in the RV heating loop
• A malfunctioning low-temperature cutoff thermostat
Stage 1:
• The RV is supplied with power
• The Aqua-Hot has an adequate supply of fuel
• All RV-side fuses are functional and able to supply power
• All water sources connected to the RV are shut off
•
The overflow bottle is filled to at least the COLD mark
Stage 2:
• Visually inspect the interior cabinet of the Aqua-Hot
unit, searching for any damaged or disconnected wires.
Reconnect or repair if necessary.
• The 250-D03 contains a 20A fuse in the wiring harness.
Make sure this fuse has not burned out.
• Make sure the high-limit thermostats are not tripped or
defective. Replace if necessary.
• Test for unit operation.
○
If the burner fails to operate, follow the procedure on
Page 96 to begin diesel burner troubleshooting.
Stage 3:
1. Begin troubleshooting the three-way valve. See Page 29.
2. Reference Page 27 to diagnose the Low-Temperature
Cutoff Thermostat.
3. Locate the circulation pump within the Aqua-Hot cabinet.
It should begin operating immediately when the heater
starts up. If the pump does not begin to operate, see the
procedure on Page 32 for troubleshooting.
4. Locate all of the heat exchangers within the RV and
determine if any of them are outputting heat.
• If at least one heat exchanger is outputting heat, an
air bubble may be preventing the flow of the antifreeze
and water heating solution.
• It may be possible to resolve this issue by allowing the
circulation pump to run continuously, checking the
heat exchangers periodically to determine if they have
begun to function. See Page 91 for the heating loop fill
& purge procedure.
At this point, if steady interior heat cannot be achieved,
contact Technical Support at 574-AIR-XCEL (574-247-9235), or
take the RV to an Aqua-Hot Factory Authorized Service Center.
One can be found at www.aquahot.com.
Ensure that all
of these tabs are
cleaned.
Figure 165
