Diagnostic Variable; Ato Value; Ats; Abs - ARP Fridge Defend Troubleshooting Manual

ARP Control v5.x Troubleshooting Guide
low temperatures measured at the boiler of
your cooling unit. If your heat sources are
confirmed to work fine, and you are
measuring low boiler temperatures, there
may be low cooling unit pressures indicating
failure of the cooling unit.
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DIAGNOSTIC VARIABLE

7.1 AtO Value

The AtO value is preset to default values if
the control has not been
Otherwise, AtO is calculated during an Auto
Tune session, the base AtO value is not
adjustable other than by running Auto Tune
again. The value of AtO can be changed by
the C-H, C-L, and PID
combination with the

7.2 AtS

AtS is only used for the PID set-point
function. AtS will not need to be changed
ordinarily. If fridge is in the PID mode, and
the ARP turns off the fridge consistently at
the startup, the AtS value can be raised
manually changing the OS setting. Also, the
AtS value is recalculated during an
Tune session if the default setting is not
working. See 'SSH' value, AtS and SSH work
together for PID function.

7.3 AbS

The AbS value is the maximum temperature
measured at the boiler since the last time
that the value was zeroed. This variable is
very handy for testing and setting the
refrigeration control values. Auto Tune
always zeros this value.
Adjustment
The AbS value may be zeroed by pressing
SetUp button. Please store any new settings
as described in section 2.22.
Purpose:
This variable is handy for recording the
cooling unit boiler temperature while the
cooling unit is in a known phase of its
process. For example, one wants to know
the absolute maximum temperature of a
cooling unit after the ARP has shut down the
04/20/202
Auto Tuned.
set-point function in
SP value.
Auto
0 © 2013-2020 ARPC L.L.C. All rights reserved.
WARNING Please take your
refrigerator to be checked by a qualified
service technician to rule out any cause that
will result in abnormally low or high
temperature readings by the ARP.
system due to an off-level overheat situation.
This will aid the operator in setting the value
of OS for a particular refrigerator installation.
Use the AbS variable in combination with the
No Set-Point
equipped with data collection capability for
the recording of restart temperatures.
7.4 tr
The tr value is simply the number of times
that the ARP has triggered since the last time
the value was zeroed. When Auto Tune is
run, tr value is zeroed.
Purpose:
Knowing the number of times the control has
triggered helps the owner understand
situations where overheating of the cooling
unit boiler occurs. For example, climbing
steep grades in hot weather often will result
in an ARP trigger event. Another example,
RV rental firms can use this information for
damage deposit and other bookkeeping
purposes.
See section 2.7
7.5 SHt & Fuses: General Electrical
Short Troubleshooting
Most RV techs are skilled at electrical short
diagnostics. This section is a brief set of
instructions on troubleshooting procedures if
repeated SHt errors are encountered.
If a short is occurring, the most likely cause
is a wire touching a ground somewhere. One
can disconnect the wire, thereby isolating the
ARP control from the short, and see if the
issue is still occurring? If the issue goes
away by disconnecting the wire, visually
inspect the wire for where the short circuit
may be? The most common cause of a short
is when wires rub on sharp metal and the
mode when the ARP is not
for clearing this variable.
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