ARP Fridge Defend - Troubleshoot Manual

Other manuals for ARP Fridge Defend

General Install Guide26 pages

User Guide10 pages

User Instructions17 pages

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Summary

Setup Mode Operations

Activating and Navigating Setup Mode

Details how to enter setup mode and operate control buttons for configuration.

Diagnostic Readings in Setup Mode

ARP Error Messages

Error Message Categories

Explains error types (operational, startup) and specific error indicators.

Common Boiler Sensor Errors

Details errors related to boiler sensor issues like OPn, SHt, and -LO.

Temperature and System Status Errors

Covers errors like *O*F*8, *H*O*8, and bAd indicating system status.

Memory and Data Integrity Errors

ARP Reset Procedure

Provides steps to reset the ARP control to factory default settings.

Diagnostic Variables

Understanding Diagnostic Variables

Electrical Short Troubleshooting

Provides guidance for troubleshooting repeated SHt errors and shorts.

Auto Tune Mode

Auto Tune Procedure

Step-by-step guide for running the Auto Tune function for fridge calibration.

RTD Troubleshooting

Checking the Boiler Sensor

Instructions for testing the boiler sensor resistance and wiring.

Troubleshooting SHt Errors

Explains common causes of SHt errors and how to resolve them.

The provided manual describes the Fridge Defend® by ARP, an accessory safety controller designed for absorption refrigeration systems in RVs. This device, also referred to as the ARP Control, monitors the boiler temperature of the refrigerator and turns off its heat source to prevent damage to the internal fluids of the cooling unit. It aims to add a level of safety to RV absorption refrigeration systems by preventing premature failure caused by overheating.

Function Description:

The ARP Control operates based on the simple physics of absorption refrigeration. The heart of an RV refrigerator is the boiler, also known as the generator, which distills ammonia refrigerant from a mixture of water, ammonia, and sodium chromate. The ARP Control monitors this distillation process. If there is no ammonia in the boiler assembly, the boiler pump will not work, causing the temperatures required to drive the system to rise. The ARP Control detects when ammonia is not being generated and intervenes by turning off the heat source before the water in the system starts to boil, which would damage the refrigerator.

The device is a hybrid single-channel IEC type accessory safety controller with a periodic self-test structure. Its software is designed using a single microcontroller unit (MCU) compliant with ISO TS 16949:2009. It executes required functions with optional periodic self-tests that occur every 24 hours when activated. These self-tests check most critical functions of the electronic control. An external watchdog timer (exWDT) is incorporated, which will turn off the refrigerator and sound an alarm (in v5.1) if the MCU becomes stuck or stops processing code. The exWDT attempts to restart the MCU, but if unsuccessful, the operator is alerted to take appropriate action. The ARP Control's ability to manage the refrigerator process is akin to a thermal fuse on the power supply, limiting its control ability for testing and self-checks.

The core function is to prevent overheating. When the ARP detects an overheat situation, it enters a countdown period before attempting a safe restart of the refrigerator. During this period, numbers on the display indicate the remaining minutes until the fridge restarts. It is crucial not to turn off the ARP Control during this time, as doing so prevents it from performing its job, and the fridge will likely overheat again.

Usage Features:

The ARP Control features a simple three-button interface: On/Off, Display, and SetUp.

Setup Mode: To activate SetUp mode, the ARP Control must first be turned off. Then, the SetUp button is held while the On/Off button is momentarily pressed. The display will show "AtO," indicating entry into SetUp mode.
- Reading Variables: These variables, like "AtO," allow the user to read values but not change them. Their values depend on other settings.
- Process Values: Variables such as "AbS" (maximum boiler temperature reached) and "tr" (number of times the ARP Control has triggered) are calculated and stored for diagnostics. These values can be reset to zero to clear current data and record new ones.
- Setting Variables: These allow the operator to change or toggle settings, such as "C-H" (Set-Point control high mode), "C-L" (Set-Point control low mode), or "PID" (proportional-integrated-derivative method). The SetUp button increments values, while the Display button advances to the next SetUp variable.
- Storing Settings: Any changes made in SetUp mode must be stored by momentarily pressing the SetUp button until "StO" is displayed. If settings are not saved, they will revert to their previous state upon exiting SetUp mode.
- Exiting SetUp Mode: To exit without saving, hold down the On/Off button until "OFF" scrolls across the screen. To exit after saving, proceed to the "Exit SetUp Mode" section.
Temperature Units: The boiler temperature units can be toggled between Celsius (C) and Fahrenheit (F) using the SetUp button.
Fan Setting: The "FAn" setting controls the temperature at which the ARP will turn the fan on/off. There are six fan temperature settings, with 4 being the default. For non-fan type ARP Controls, this setting is fixed at 0 and cannot be changed.
SP Setting: "SP" adjusts the set-point value of the ARP Control. The default is 5. This variable is used in C-L or PID modes to fine-tune protection and restart sensitivity.
OS Setting: "OS" is the temperature overshoot value, rarely changed, with a default of 5. It helps determine the higher temperature needed to restart the refrigeration process after the heat source has been turned off due to an abnormality.
Defrost Setting/IEC Periodic Test: The "PEr" setting allows overriding the refrigerator's defrost cycle, potentially improving cooling in warm weather. "PEr = on" means the IEC periodic test runs every 24 hours, and the factory defrost cycle is defeated. "PEr = OFF" disables the IEC test and allows the factory defrost cycle to run.
Audible Alarm (v5.1 only): This setting controls the beeper. "bEP = on" is the default, and the alarm sounds during some IEC tests when an error occurs. It can be toggled "oFF" to prevent sounding.
No Set-Point Mode (SP0): This mode is for testing the refrigerator without the ARP's overheat protection. It displays fridge voltage, which is useful for diagnosing issues like low voltage (below 10.5VDC) that prevent the fridge from turning on, or detecting AC current on the RV 12VDC line. It also includes a sensor troubleshooting test and records MAX/MIN fridge voltage. Caution is advised when using this mode due to the lack of overheat protection.
Auto Tune Mode: This mode is used to automatically determine the fridge's unique control parameters if the default settings (C-H, C-L, or PID) are not working. It requires the cooling unit to be working properly and the ARP Control to be installed correctly. To start, hold both the SetUp and Display buttons, then momentarily press On/Off. The display will show "At." Auto Tune should run continuously for 24 hours, ideally 12 hours on LP gas and 12 hours on 120VAC, using both heat sources for accuracy. Any power interruption during Auto Tune necessitates running it again.

Maintenance Features:

The ARP Control incorporates several diagnostic and troubleshooting features to aid in maintenance and issue resolution.

Error Messages: The device stores IEC error messages, accessible via the "Er0" variable in SetUp mode. These messages provide insights into operational errors, startup, or periodic test errors.
- Operational Errors: These display while the control is running or during user tests. Examples include:
  - *Err (first dot on upper left): Indicates ARP memory cleared, possibly due to incorrect Auto Tune or voltage surges. Resolution involves restoring ARP Defaults.
  - OPn Boiler Sensor: Warns of an open RTD or wiring error, disabling ARP protection. Requires testing RTD resistance and checking wiring.
  - SHt Boiler Sensor: Indicates a short circuit in the RTD sensor or wiring. Requires checking sensor resistance and wiring for shorts.
  - -LO Boiler Sensor Reading: Sensor reading below 0°C (32°F).
  - *O*F*8: ARP has attempted to restart the fridge 5 times and failed due to overheating. Requires cooling the boiler and restarting the system cautiously.
  - *H*O*8: Excess temperature shutdown (boiler reached 250°C). Requires checking the fridge for failure and allowing it to cool to ambient temperature.
  - OR (OA) Fan Temp Reading: Fan sensor is outside its normal measurement range (35°F to 155°F).
  - bAd: Auto Tune failure, possibly due to the boiler sensor being too close to a heat source.
  - F4 or F5 SetUp Button Test: Indicates an issue during the automatic controller test.
  - E8 Error: A rare error, if it persists after a restart, contact support.
  - E10 Flashing: Internal relay failure or incorrect wiring during a test.
  - E11 Trigger Event: Overheat detected, but power was not turned off.
  - F1 MCU ADC Error Checker: Electrical noise on RV wiring, not critical for boiler temperature measurement.
- Startup or Periodic Test Errors (SPT): These errors are tested at startup and every 24 hours if "PEr = on." Examples include:
  - F2 at ARP Startup: Indicates incorrect wiring where the ARP internal relay cannot turn off power to the yellow wire. Requires rewiring.
  - F3 Boiler Sensor ADC Cal: Electrical noise on RV wiring, can be checked in SP0 mode.
  - CRC Tests (F6, F7, E13): Check code integrity within the MCU. Failures can be due to power supply brown-outs, electrical noise, or memory corruption. Often resolved by restoring factory default settings.
  - E12, E14, E15 MCU Tests: Electrical noise on RV wiring.
ARP Reset Procedure: Turning off the ARP Control and then back on will reset it, resuming boiler temperature monitoring. However, if an overheat situation was detected, it's recommended to let the ARP manage the restart process.
RTD Troubleshooting: The manual provides a detailed RTD (Resistance Temperature Detector) table and instructions for checking the boiler sensor's resistance using a multi-meter to diagnose open circuits or shorts. This helps verify the integrity of the sensor and its wiring.
Boiler Temperature Monitoring: The ARP Control continuously monitors boiler temperature, providing a key indicator of refrigerator health. Users are advised to record "normal" boiler temperatures for both LP gas and electric heat sources for future troubleshooting.
SPAR Pressure Indicators: Low boiler temperatures, even with confirmed working heat sources, can indicate low cooling unit pressure, a sign of cooling unit failure. The ARP can serve as an indicator for this, previously only measurable by a cooling unit rebuilder.
RV Storage & Startup Tips: The manual offers guidance on preparing the RV for storage and travel, including battery maintenance, LP gas management, and defrosting the fridge. It emphasizes checking RV living space battery voltage with the ARP Control before turning on the fridge to ensure healthy power supply.

Overall, the Fridge Defend by ARP is a comprehensive safety and diagnostic tool designed to protect RV absorption refrigerators from overheating, provide valuable diagnostic information, and assist users in maintaining their refrigeration systems.

ARP Fridge Defend Specifications

General

Category	Automobile Accessories
Features	reverse polarity protection
Operating Temperature	-40°C to +85°C
Protection Features	reverse polarity protection
Purpose	Protects RV refrigerators from damaging power surges and voltage fluctuations