ARP Fridge Defend User manual

Fridge Defend® by ARP
Condenser
Absorber Coil
LIQUID : Water;
Ammonia; Sodium
Chromate
Refrigerated Space
Boiler Assembly
Q2
Q3
Q1
Evaporator
Cooling
Fin
Boiler
Percolator
Pump
Q1=Q2+Q3
v5.x ARP & ARP + Fan Control
Troubleshooting Guide
Please click here for Online ARP Video Operation Manual
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Terms -- Conditions & Contact Information
This manual is copyrighted © by ARPC L.L.C. 2013-2020. All rights are reserved. This manual may only be reproduced
with permission of ARPC L.L.C.. This manual is furnished for informational use only and is subject to change without
notice. This manual does not imply any commitment on the part of ARPC L.L.C. or its business partners. ARPC L.L.C.
and its business partners assume no responsibility or liability for any error or inaccuracies that may appear in this manual.
By use of this document for installation and operation of the ARP Control (Fridge Defend®), the user is agreeing to the
ARPC L.L.C. terms and conditions found in document ARPC LLC License Agreement.pdf. Also, the end user needs to
understand that the ARP Control can be turned off at any time, thereby removing the ARP Control function and reverting
to the operation of the refrigerator to its previous state. Also, the self-test functions which make the Fridge Defend an
accessory safety control may be turned off by the end user; this will defeat the 24 hour self-test. Power surges can turn off
the ARP Control just the same as any equipment in an RV, thus it is the operators responsibility to insure that the control
is functioning properly. Any ARP Control that is believed to be malfunctioning, the ARP Control must be removed from
operation and returned to ARPC L.L.C. for inspection immediately. Contact ARPC L.L.C. for shipping instructions. The
reason for return must be included in writing with the returned control; shipping is the responsibility of the end user to
and from ARPC L.L.C..
The document "ARPC LLC License Agreement.pdf" can be downloaded at web address
http://www.ARPrv.com
or, please send any request to e-mail address below, ARPC L.L.C. will supply information in a timely manner:
[email protected]
Cover Diagram
The diagram on the cover is a block diagram showing the flow of the refrigerant fluids. Q1 is
the liquid water and ammonia which enters the boiler. Within the boiler ammonia is changed
from liquid to gas Q3, and in turn forces the remaining water Q2 up the pump tube. At the top
of the pump tube the two paths for the fluids Q2 and Q3 diverge. The ammonia gas Q3 cools
the refrigerated space and then returns to the absorber coil where the water Q2 enters. Within
the absorber coil the two fluids are recombined to reconstitute the refrigerant Q1 to repeat the
cycle.

CONTENTS
SAFETY .................................................................................................................................... 1
1.1 Acronyms and Abbreviations................................................................................... 1
1.2 Hazard Information.................................................................................................... 1
1.3 Terms & Warnings Symbols..................................................................................... 1
1.4 Work Safely................................................................................................................ 1
1.5 Operation Safety........................................................................................................ 1
SETUP MODE........................................................................................................................... 1
2.1 Activate SetUp Mode................................................................................................. 1
2.2 Types of SetUp Mode Variables............................................................................... 2
2.3 SetUp Mode Button Operation ................................................................................. 2
2.4 AtO Reading............................................................................................................... 2
2.5 AtS Reading............................................................................................................... 3
2.6 AbS Process Value.................................................................................................... 3
2.7 tr Process Value ........................................................................................................ 3
2.8 OPn Process Value.................................................................................................... 4
2.9 SHt Process Value..................................................................................................... 4
2.10 SSH Process Value.................................................................................................. 4
2.11 FAn Setting .............................................................................................................. 4
2.12 SP Setting................................................................................................................. 5
2.13 OS Setting................................................................................................................ 5
2.14 Adjustment of SP or OS Settings........................................................................... 5
2.15 Temperature Units................................................................................................... 6
2.16 Set-Point Function Setting...................................................................................... 6
2.17 Defrost Setting/IEC Periodic Test .......................................................................... 7
2.18 Software Version Reading...................................................................................... 7
2.19 Serial Number Reading........................................................................................... 7
2.20 Audible Alarm (5.1 only).......................................................................................... 7
2.21 Restore ARP Defaults.............................................................................................. 7
2.22 Store Settings.......................................................................................................... 8
2.24 Exit SetUp Mode ...................................................................................................... 8
ARP ERROR MESSAGES........................................................................................................ 9
IEC Type Accessory; Redundancy; Systematic Faults & Self-Checks........................ 9
Fridge OFF; Buzzer Sounding (v5.1); Right Dot Illuminated......................................... 9
3.1 Error Message List .................................................................................................... 9
3.2 123 Numbers on Display (not an error).................................................................. 10

3.3 *Err (first dot on upper left)..................................................................................... 10
3.4 OPn Boiler Sensor................................................................................................... 10
3.5 SHt Boiler Sensor.................................................................................................... 11
3.6 -LO Boiler Sensor Reading..................................................................................... 11
3.7 *O*F*8 ....................................................................................................................... 11
3.8 *H*O*8....................................................................................................................... 11
3.9 OR (OA) Fan Temp Reading ................................................................................... 11
3.10 bAd ......................................................................................................................... 11
3.11 F4 or F5 SetUp Button Test .................................................................................. 11
3.12 E8 Error .................................................................................................................. 12
3.13 E10 Flashing when Test ARP with SetUp Button ............................................... 12
3.14 E11 Trigger Event.................................................................................................. 12
3.15 F1 MCU ADC Error Checker.................................................................................. 12
3.16 F2 at ARP Startup.................................................................................................. 12
3.17 F3 Boiler Sensor ADC Cal..................................................................................... 12
3.18 CRC Tests .............................................................................................................. 12
3.19 E12, E14, E15 MCU Tests...................................................................................... 12
3.20 ARP Reset Procedure............................................................................................ 13
INTRODUCTION to FRIDGE REPAIR.................................................................................... 13
4.1 Refrigerant ............................................................................................................... 13
4.2 Boiler Operation ...................................................................................................... 13
4.3 Boiler Pump ............................................................................................................. 13
4.4 ARP Control and the Boiler .................................................................................... 13
4.5 Burping a SPAR....................................................................................................... 13
4.6 Abnormalities and Operator Discretion................................................................. 13
HEAT SOURCES.................................................................................................................... 14
5.1 Temperature & Pressure......................................................................................... 14
5.2 Low LP Gas Pressure.............................................................................................. 14
5.3 Test Each Heat Source............................................................................................ 14
SPAR PRESSURE.................................................................................................................. 14
6.1 Low Cooling Unit Pressure..................................................................................... 14
DIAGNOSTIC VARIABLE....................................................................................................... 15
7.1 AtO Value ................................................................................................................. 15
7.2 AtS ............................................................................................................................ 15
7.3 AbS ........................................................................................................................... 15
7.4 tr................................................................................................................................1
5

7.5 SHt & Fuses: General Electrical Short Troubleshooting...................................... 15
7.6 SSH........................................................................................................................... 16
CONTROL VARIABLES......................................................................................................... 16
8.1 Introduction to Control Variables........................................................................... 16
8.2 SP.............................................................................................................................. 16
8.3 OS ............................................................................................................................. 17
ADJUSTMENT VARIABLES .................................................................................................. 17
9.1 C or F........................................................................................................................ 17
9.2 C-H, C-L, or PID Set-Point Methods ....................................................................... 17
9.3 Fan Temperature Diagnostic.................................................................................. 17
NO SET-POINT MODE (SP0)................................................................................................. 18
10.1 Test Fridge Voltage ............................................................................................... 18
10.3 Sensor Troubleshooting Test............................................................................... 18
10.4 MAX/MIN Fridge Voltage Record.......................................................................... 18
AUTO TUNE MODE................................................................................................................ 19
11.1 Auto Tune Procedure............................................................................................ 19
11.2 Auto Tune & Set-Point Function .......................................................................... 19
RV STORAGE & STARTUP TIPS .......................................................................................... 20
12.1 Storage – RV Batteries; LP Gas; Fridge .............................................................. 20
12.2 Get Ready to Go – Dry Run................................................................................... 20
12.3 RV Battery Voltage & Fridge................................................................................. 20
12.4 Get Fridge Ready for Travel.................................................................................. 21
RTD TROUBLESHOOTING.................................................................................................... 21
13.1 Check Boiler Sensor ............................................................................................. 21
13.2 SHt Error................................................................................................................. 21
RTD TABLES.......................................................................................................................... 21

ARP Control v5.x Troubleshooting Guide 0©2013-2020 ARPC L.L.C. All rights reserved.
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SAFETY
1.1 Acronyms and Abbreviations
ARP: ARP Control = Fridge Defend
RTD: ARP Control temperature sensor;
Resistance Temperature Detector is the type
of sensor used.
Q: Flow of fluid either as a gas or liquid.
SPAR: Single Pressure Absorption
Refrigerator.
1.2 Hazard Information
Hazard information includes terms, symbols
and instructions used in this manual or on
the equipment to alert operating and service
personnel to the recommended precautions
in the care, use and handling of the ARP
Control.
1.3 Terms & Warnings Symbols
1.4 Work Safely
There are many ways to install the ARP
Control. Make safety your first priority!
The installer’s knowledge, skill, and ability
are important for safely installing the system
and maintaining or troubleshooting it. If you
are unsure of your ability to use the ARP as
a diagnostic tool, have a qualified individual
do the work.
1.5 Operation Safety
The ARP Control and 'ARPrvSafe' infer that
the use and operation of this control can add
a level of safety to your absorption
refrigeration system in your RV. No other RV
absorption refrigerator control monitors the
boiler temperature, and turns off the heat
source to the refrigerator before damage can
be done to the internal fluids in the
refrigerator cooling unit. The ARP cannot
prevent RV refrigerator failure if the
manufacture built the cooling unit in a
manner that would result in premature failure.
In addition, if damage to the cooling unit has
occurred before the ARP was installed; the
ARP cannot remedy this damage
__________________________________________________________________________________________
SETUP MODE
2.1 Activate SetUp Mode
On/Off Display SetUp
To place the control into SetUp mode, begin by turning
off the ARP Control (Please see User Guide →Turn off
ARP Control). When the control is off, the SetUp mode is
activated by holding*the right SetUp button and then
momentarily*pressing the On/Off button. When AtO is
displayed, release the SetUp button.
*Please see User Guide section BUTTON FUNCTION
& Ancillary Graphical User Instructions section Turn
ON Control in SetUp Mode .

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2.2 Types of SetUp Mode Variables
There are 3 types of SetUp mode variables as follows:
1) Reading Variable: Example, AtO is a reading type variable because the user can only
read the value. Its value is dependent upon another setting.
2) Process Value*: Example, the ARP stores values such as AbS. AbS is calculated by
the ARP and stored for diagnostics. The user cannot change the value of AbS, the
value can only be reset to zero in order to clear the present value so that the ARP can
record new values in the future.
3) Setting*:Example, C-H is a setting that the operator can change/toggle to modify the
setting. C-H setting changes the ARP set-point function. The present choice for the
set-point will be displayed in the Reading Variable AtO.
* Please note that all Process Values and Setting changes need to be stored before
exiting the SetUp mode. See 2.22 Store Settings.
2.3 SetUp Mode Button Operation
The three buttons on the ARP Control that performs the following functions when in the SetUp
mode:
On/Off Button: Turn off the control by pressing and holding till OFF is displayed, and then
cleared.
Display Button: The display button is used to advance to the next SetUp variable. By
repeated pushing of the display button the variables will advance to the store function (S--),
then Er0, and then rotate back to the first variable AtO.
SetUp Button: The SetUp button will change the value of either a Process Value or a Setting
variable. Each push of the SetUp button will increment the value by 1 up to the maximum value,
and then rotate back to either zero or 1 to restart the sequence.
2.4 AtO Reading
AtO will display followed by the present value or Set-
Point function*selection, see 2.16 Set-Point Function
Setting. The following table shows the default values for
AtO:
Set-Point Function AtO Value
C-H C-H
C-L 196
PID 196
Example of default value being displayed:
*Use the charts for both AtO and AtS to determine the
present Set-Point function and values.

ARP Control v5.x Troubleshooting Guide 0©2013-2020 ARPC L.L.C. All rights reserved.
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2.5 AtS Reading
AtS complements the AtO reading by providing further
Set-Point function selection information as follows:
Set-Point Function AtS Value
C-H 217
C-L C-L
PID 231*
*If the Set-Point function has been set to PID, AtS will
display a value. The default value is 231, more on this
subject in the Auto Tune and OS sections.
2.6 AbS Process Value
On/Off Display SetUp
AbS is the maximum temperature the boiler has reached.
The example below, 200C (See 2.15 Temperature Units)
would be the maximum temperature recorded by the
ARP since the last time that AbS was cleared.
Please see section 7.3 for detailed information.
By pressing the SetUp button, the AbS value will be
cleared. When the AbS value has been cleared, -LO will
flash on the display until the control is put into the ARP
mode to record a new maximum value.
Any changes must be stored, see 2.22 Store Setting.
Please note that if AbS is greater than 250°C (482°F)
there may be a wiring or cooling unit issue, please
contact ARP technical support.
2.7 tr Process Value
Tr is the number of times that the ARP Control has
triggered since the value was last cleared. The following
example shows that the ARP turned off the fridge twice:
Please see section 7.4 for further info.
Push the SetUp button to zero the tr value. Also see 7.4.
Any changes must be stored, see 2.22 Store Setting.

ARP Control v5.x Troubleshooting Guide 0©2013-2020 ARPC L.L.C. All rights reserved.
404/20/202
2.8 OPn Process Value The OPn value is a count of how many times the ARP
boiler sensor has had a wiring or sensor open condition.
Please see section 3.4 OPn for further information.
If there is an intermittent problem due to vibration or a
bad crimp connection, OPn will record the total number of
times the circuit opens and closes. Push the SetUp
button to zero the OPn value. Any changes must be
stored, see 2.22 Store Setting.
2.9 SHt Process Value
The SHt value is a count of how many times the ARP
boiler sensor has had a short circuit. When the ARP
Control is in the ARP mode of operation, and either the
wiring or sensor is measured as a short circuit, SHt will
flash on the screen. SHt will record the total number of
times the boiler sensor has an intermittent short circuit
and then returns to normal operation. A short in the
sensor circuit is usually do to either the two sensor wires
touching or a sensor wire shorted to chassis ground.
See 3.5 SHt and RTD TROUBLESHOOTING for further
information.
2.10 SSH Process Value
On/Off Display SetUp
The SSH value measures the boiler steady-state
maximum temperature. This value is only valid if the
control has been set to the PID control mode, see Set-
Point Function Setting section below.
If the control is tripping in the PID control mode, this
variable is very valuable for troubleshooting when
combined with the above AbS value. If the AbS value is
greater than the AtS value, the start up is tripping the
fridge. If the SSH value is greater than AtO value, the
control is tripping when in steady-state operation.
2.11 FAn Setting
FAn is the temperature setting at which the ARP will turn
On/Off the fan. There are six fan temperature settings to
select from.
For a non-fan type ARP Control, the fan setting is a fixed
number 0 and cannot be changed.
By momentarily pressing the SetUp button the fan control
temperature can be set to a desired value. Any changes
must be stored, see 2.22 Store Setting.
4 is the default fan setting value.

ARP Control v5.x Troubleshooting Guide 0©2013-2020 ARPC L.L.C. All rights reserved.
504/20/202
Fan
Setting ON Temperature °F OFF Temperature °F
000 Fan Off
001 110 95
002 115 100
003 120 105
004 125 110
005 130 115
006 135 120
2.12 SP Setting
SP raises the set-point value of the ARP Control. The
default setting for SP is 5.
See section 8.2 for further information.
2.13 OS Setting
The OS setting is used for the restart of the refrigerator.
This value is rarely, if ever changed.
The default setting of OS is 5.
See section 8.3 for further information.
2.14 Adjustment of SP or OS Settings
By pressing the SetUp button the control enters into the
adjustment mode. Both SP and OS are adjusted in the
same manner as described below.