Controller
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 11
The Aqua-Hot Controller
Introduction:
The Aqua-Hot 250-D03 operates on a controller platform
which has been modernized and updated from the previously
used Electronic Controllers and Relay Control Boards of older
Aqua-Hot units.
This controller is best utilized with either the Aqua-Hot
display or RV LCD display. Using the Aqua-Hot with either
displays will ensure that you can take advantage of all of the
tools and features of this controller.
Features:
This new controller brings with it new features to it which
effect functionality from every stage of operation. Fail safe
functionality, climate control, and troubleshooting and
diagnostics have all been overhauled on this new control
architecture. These features will be explained in detail below.
Troubleshooting:
The new troubleshooting functionality is perhaps the largest
and most substantial change to come about from the new
controller architecture. Many faults and failures within the
Aqua-Hot can now be relayed in plain language to the technician
servicing the Aqua-Hot. There are five system faults which will
be utilized; System Voltage, Low-Level Cutoff, Over-Current,
Overheat, and Burner Failed to Ignite. These will be explained
below.
System Voltage:
System voltage faults indicate that there is a
problem with the RV-side power supply which
powers the Aqua-Hot.
The Aqua-Hot can only operate within a
voltage range of 11V DC to 16V DC. If voltage
drops below 11V, or exceeds 16V DC, the
controller will shut down the Aqua-Hot as a
safety mechanism.
Low-Level Cutoff:
The Low-Level Cutoff fault will only trigger if
the minimum fluid level within the Aqua-Hot
is below an acceptable operational threshold.
If the controller is showing a low-level cutoff
fault, begin by diagnosing the fluid sensor.
Over-Current:
Over-current faults are triggered by an output
channel (pump, fan, etc) that is attempting
to draw too much current through the
controller. This fault will be accompanied by
the component which triggered the fault,
for example “PUMP 2 OVER-CURRENT” will
display if Pump 2 is not operating correctly.
If over-current faults are appearing on the
display, troubleshoot the offending component
listed as being over-current.
Overheat:
Overheat faults indicate that the unit has
exceeded its overheat threshold of 210°F.
If an overheat condition has occurred,
diagnose the cause of the overheat by
investigating the heating sub-systems of the
Aqua-Hot (electric and/or diesel burner ).
Under-Current
Under-current faults indicate that the unit
does not have enough voltage to properly
operate. If voltage drops below 11V, the
controller will shut down the Aqua-Hot as a
safety mechanism.
If an under-current fault is displayed on the
screen, troubleshoot the offending component
listed and also check power into the Aqua-Hot.
The fault codes shown above will cover the most common Aqua-
Hot related issues. For more complex issues, it may be
Figure 5
Figure 6
