Carel pRack pR300 and pR100T

pCO-based controllers for compressor racks and condensers, up to two suction lines. Alarms are grouped by letter: A probes, B pressures and levels, C compressors, E valve drivers, F fans, G generic and clock, T maintenance, U configuration, W warnings.

What it is: Compressor rack controller. pR300 for standard racks and pR100T for transcritical CO2 racks. Both use the same ALA / ALB / ALC… code system.

Key combo: Use the graphic terminal menu. Higher menus need the maintenance or manufacturer password: enter the service password when asked.

Error codes ↓
Enter service mode ↓
Change a setting ↓

Carel pRack pR300 and pR100T error codes

Code	Meaning	Reset
ALA01	Discharge temperature probe fault	Automatic
ALA02	Condensing pressure probe fault	Automatic
ALA03	Outside temperature probe fault	Automatic
ALA04–ALA23	Generic probe A to E fault on expansion boards PLB1 to PLB4	Automatic
ALA24	Suction pressure probe fault	Automatic
ALA25	Suction temperature probe fault	Automatic
ALA26	Room temperature probe fault	Automatic
ALA27	Condensing pressure probe fault, line 2	Automatic
ALA28	Discharge temperature probe fault, line 2	Automatic
ALA29	Suction pressure probe fault, line 2	Automatic
ALA30	Suction temperature probe fault, line 2	Automatic
ALA31	Condensing pressure backup probe fault	Automatic
ALA32	Condensing pressure backup probe fault, line 2	Automatic
ALA33	Suction pressure backup probe fault	Automatic
ALA34	Suction pressure backup probe fault, line 2	Automatic
ALA35	Common oil temperature probe fault	Automatic
ALA36	Common oil temperature probe fault, line 2	Automatic
ALA39	Discharge temperature probe fault, compressors 1 to 6	Automatic
ALA40	Discharge temperature probe fault, compressors 1 to 6, line 2	Automatic
ALA41	Oil temperature probe fault compressors 1 to 6, line 1	Automatic
ALA42	Oil temperature probe fault compressor 1, line 2	Automatic
ALB01	Low suction pressure from pressure switch	Semiautomatic
ALB02	High condensing pressure from pressure switch	Manual or automatic (set by parameter)
ALB03	Low condensing pressure from probe	Automatic
ALB04	High condensing pressure from probe	Automatic
ALB05	Liquid level	Automatic
ALB06	Common oil differential	Automatic
ALB07	Common fan circuit breaker	Automatic
ALB08	Low suction pressure from pressure switch, line 2	Semiautomatic
ALB09	High condensing pressure from pressure switch, line 2	Manual or automatic (set by parameter)
ALB10	Low condensing pressure from probe, line 2	Automatic
ALB11	High condensing pressure from probe, line 2	Automatic
ALB12	Liquid level, line 2	Automatic
ALB13	Common oil differential, line 2	Automatic
ALB14	Common fan circuit breaker, line 2	Automatic
ALB15	High suction pressure from probe	Automatic
ALB16	Low suction pressure from probe	Automatic
ALB17	High suction pressure from probe, line 2	Automatic
ALB18	Low suction pressure from probe, line 2	Automatic
ALB21	Shutdown to prevent high pressure	Manual
ALB22	Shutdown to prevent high pressure, line 2	Manual
ALE01	EEV motor error on Driver 1	Automatic
ALE02	Low superheat on Driver 1	Automatic
ALE03	EEV motor error on Driver 2	Automatic
ALE04	Low superheat on Driver 2	Automatic
ALE05	EEPROM error on Driver 1 in PLB1	Automatic
ALE07	EEPROM error on Driver 1 in PLB3	Automatic
ALE08	EEPROM error on Driver 2 in PLB1	Automatic
ALE10	EEPROM error on Driver 2 in PLB3	Automatic
ALE11	Parameter transmission error on Driver 1	Automatic
ALE12	Parameter transmission error on Driver 2	Automatic
ALE13	FW compatibility error on Driver 1	Automatic
ALE14	FW compatibility error on Driver 2	Automatic
ALF01	Fan circuit breaker	Manual or automatic (set by parameter)
ALF02	Fan circuit breaker, line 2	Manual or automatic (set by parameter)
ALG01	Clock error	Automatic
ALG02	Extended memory error	Automatic
ALH01	ChillBooster fault	Automatic
ALH02	ChillBooster fault, line 2	Automatic
ALO02	pLAN fault	Automatic
ALT01	Compressor maintenance request	Manual
ALT02	Compressor maintenance request, line 2	Manual
ALT03	ChillBooster maintenance request	Manual
ALT04	ChillBooster maintenance request, line 2	Manual
ALU01	Configuration not allowed	Automatic
ALU02	Control probes missing	Automatic
ALW01	High pressure prevent warning	Automatic
ALW02	High pressure prevent warning, line 2	Automatic
ALW03	Compressor inverter warning	Automatic
ALW04	Compressor inverter warning, line 2	Automatic
ALW05	Fan inverter warning	Automatic
ALW06	Fan inverter warning, line 2	Automatic
ALW07	Envelope warning: refrigerant not compatible with compressor series	Automatic
ALW08	Envelope warning: custom envelope not configured	Automatic
ALW09	Envelope warning: suction or condensing probes not configured	Automatic
ALW10	Low superheat warning	Automatic
ALW11	Low superheat warning, line 2	Automatic
ALW12	Warning, ChillBooster operating without outside sensor	Automatic
ALW13	Warning, ChillBooster operating without outside sensor, line 2	Automatic
ALC01–ALC99	Compressor alarms: each compressor has its own alarm inputs, line 1 then line 2	Manual or automatic (set by parameter)
ALG11–ALG34	Generic function alarms on PLB1 to PLB4	Manual or automatic (set by parameter)

How to enter service / parameter mode

Press the programming (PRG) key on the graphic terminal. A password prompt appears.
Enter the service password. Access stays open for 5 minutes after the last key press.
Pick the menu branch with UP / DOWN and press ENTER. What you see depends on the level: user, maintenance or manufacturer (shown as 1, 2 or 3 lines in the top right corner).

How to change and save a setting

Move the cursor to the value with ENTER.
Change it with UP / DOWN.
Press ENTER to confirm and move on.
Press ESC to go back.

Other useful key presses

Task	How
Alarm list	Press the alarm (bell) key to see active alarms and the reset option.

Notes

The list follows the pR300 manual. The pR100T adds CO2 codes: ALA43 gas cooler outlet temperature probe fault, ALA44 CO2 receiver pressure probe fault, ALA45 gas cooler outlet backup probe fault, extra warnings ALW14–ALW22 (probe type not allowed, auto-configuration error, oil receiver levels, valve driver probe, memory, motor, offline and battery) and more maintenance requests (ALT07–ALT18).
On the pR100T, ALB03 / ALB04 refer to low / high gas cooler outlet temperature rather than condensing pressure.
Compressor alarm meanings (ALC) depend on how each alarm input was set up on the rack. Check the compressor alarm configuration screens.
Our check of the pR100T table found ALA02 described the same as ALA01. Confirm on the unit.

For licensed technicians only. This equipment can involve mains voltage, high-voltage microwave circuits, gas and refrigerant. Isolate power (and gas) before opening panels, follow the manufacturer's manual and your local licensing rules (for example ARC refrigerant handling and electrical or gas licences). Wrong settings can spoil food or damage equipment. Check every value on the unit in front of you before changing it.

Based on: Carel pRack pR300 user manual (+0300025EN) and pRack pR100T user manual (+0300022EN rel. 1.0). Always check the manual for your exact model and software version.

ServiceModes is not affiliated with Carel or any other manufacturer. Written in our own words from the manufacturer's documentation.