The Bitzer CM-RC-01 compressor module (IQ MODULE) shows its status with four colored LEDs, and in the sections we reviewed Bitzer describes each one as lit, not as a blink code. Per Bitzer KT-230-4, section 9.1: green means normal operation; yellow means at least one sensor value has passed its warning threshold (BEST SOFTWARE mode WARNING or CRITICAL ALARM); red means the compressor motor has been stopped (BEST SOFTWARE mode FAULT); and blue means data is being transmitted over the Modbus or Bluetooth interface. To see which value caused a yellow or red light, read the alarm list in Bitzer's BEST SOFTWARE.
CM-RC-01 LED colors and what they mean
| LED | Meaning (Bitzer KT-230-4, section 9.1) | BEST SOFTWARE mode | Compressor (KT-230-2, section 9) |
|---|---|---|---|
| Green, lit | Normal operation | Normal | No alarm |
| Yellow, lit | At least one sensor value has exceeded its warning threshold | WARNING or CRITICAL ALARM | Still running; switched off if a critical alarm does not recover within its time delay |
| Red, lit | Compressor motor is stopped | FAULT | Off |
| Blue, lit | Data is being transmitted via the Modbus or Bluetooth interface | Not an alarm | Communication only |
KT-230-4 says the LEDs are visible through one or two sight glasses on the side of the module housing. The earlier English edition, KT-230-2, describes the blue LED as Modbus data only; KT-230-4 adds Bluetooth.
Does the CM-RC-01 have blink codes?
Not in the sections of Bitzer's KT-230 documentation that we reviewed (the LED and alarm-level sections of KT-230-4 and KT-230-2). Both describe each LED as lighting up and give no flash-count table, unlike modules that report numbered codes. The color tells you the alarm level. It does not tell you which sensor caused it. For that, connect with BEST SOFTWARE. KT-230-4 says the alarm messages are recorded and can be displayed as an alarm list there, and KT-230-2 shows selecting IQ MODULE CM-RC-01 in the software.
Yellow LED: warning or critical alarm?
A yellow LED covers two of Bitzer's three alarm levels, and the difference matters because only one of them is about to stop the compressor. KT-230-2 defines the levels this way:
| Alarm level | Definition (Bitzer KT-230-2, section 9) | LED | Compressor |
|---|---|---|---|
| Warning | The warning threshold is exceeded when the application limit is almost reached | Yellow | Keeps running |
| Critical alarm | The cut-out value is exceeded | Yellow | Switched off if the measured value does not drop again within the corresponding time delay; that cut-out is classified as a fault in the alarm list |
| Fault | The cut-out value has been exceeded too much or for too long | Red | Switched off |
KT-230-2 also says that before a sensor value reaches a critical limit, the module issues a warning message over the Modbus RS485 interface (CN14). KT-230-4 says that depending on the measured value, up to three alarm levels are defined, and that the warning messages can be used by the higher-level system controller as a basis for control.
Our practical reading: a yellow light on a running compressor is a prompt to check the alarm list now. If it is a critical alarm, the compressor may stop on its own once the delay runs out, and the light will change to red.
What the module is watching
Per KT-230, the CM-RC-01 monitors the main operating parameters of the reciprocating compressor: motor and discharge gas temperature, oil supply and the application limits. The monitored functions are:
- Motor temperature.
- Discharge gas temperature.
- Oil supply, through an OLC-D1 oil level monitor or a DP-1 differential oil pressure switch, depending on the compressor.
- Application limits (condensing and evaporating temperature), using low and high pressure transmitters.
- Compressor switching frequency.
When the light goes yellow or red, those are the places to look, after the alarm list has told you which one tripped. If the alarm points at oil supply, check the oil level and the oil sensor before you suspect the module.
Red LED: will it restart on its own?
It depends on the fault. KT-230-2 says that when a fault occurs, the module switches off the compressor motor and, depending on the type of fault, either resets automatically with a time delay or locks and must be reset externally. We could read KT-230-4's LED and alarm-level sections but not its reset section, so the details below come from KT-230-2. Check the reset instructions in the edition supplied with your module.
- Automatic time-delayed reset. Once the value that caused the fault falls below the restart threshold, the motor is switched on again after a time delay and the alarm becomes inactive. The factory setting is 60 seconds, adjustable in BEST SOFTWARE. KT-230-2 says the module locks after too many automatic resets, without giving a count.
- Unlocking a locked module. KT-230-2 lists a Modbus command (Control Word), BEST SOFTWARE under ALARMS, RESET, disconnecting the L/N supply for at least 5 seconds, or switch S2 (reset). All system-related alarms except motor temperature monitoring can be unlocked via Modbus or BEST SOFTWARE.
- Motor temperature. If the motor temperature is too high, the module locks itself. To unlock it, KT-230-2 says the L/N supply must be interrupted for at least 5 seconds.
Find and fix the cause before you unlock. A module that locks again right after a reset is telling you the condition is still there.
Parts involved
| Component | Role in this issue | Where to find it |
|---|---|---|
| CM-RC-01 compressor module | Shows the LED status, records alarms and switches the compressor off on a fault. | Send the compressor model and serial number through the request a quote page |
| OLC-D1 or DP-1 oil supply sensor | KT-230 lists these for oil supply monitoring. An oil supply alarm points here or at the oil level. | Request a quote with the compressor model |
| Low and high pressure transmitters | Used for application limit monitoring. | Controls |
| Bitzer compressor | The compressor the module protects. KT-230 covers Bitzer reciprocating compressors. The compressors in the linked collection are GSD scroll models, which this module's documentation does not cover, so match by model, not by collection. | Bitzer Compressors |
Scope: This article covers the LED indications, alarm levels and reset methods of the Bitzer CM-RC-01 compressor module for reciprocating compressors, as described in Bitzer KT-230-4 (section 9.1 LED meanings, German original) and the earlier English edition KT-230-2 (alarm levels, reset). Where the two editions differ, we say so. It does not cover the CM-RC-02 or other Bitzer protection devices. The parts and collections above are examples, not a fit confirmation for your compressor.
Before you order
Read the compressor model and serial number from the compressor nameplate and the label on the module. If your compressor uses a CM-RC-02, see Bitzer SE-B1 replacement: the CM-RC-02 in Protection Mode. For oil supply alarms, see how full a Bitzer oil sight glass should be. To confirm fit, contact us at help@totalhvacparts.com or 302-219-4994 with the compressor model, serial number and the alarm shown in BEST SOFTWARE.
Frequently Asked Questions
What do the lights on a Bitzer IQ module mean?
On the CM-RC-01, green means normal operation, yellow means a sensor value has passed its warning threshold (warning or critical alarm), red means the compressor motor is stopped (fault), and blue means data is being sent over Modbus or Bluetooth, per Bitzer KT-230-4.
Why is the yellow light on my Bitzer CM-RC-01?
At least one measured value has exceeded its warning threshold. It is either a warning, where the compressor keeps running, or a critical alarm, where the compressor is switched off if the value does not drop within its time delay. Check the alarm list in BEST SOFTWARE to see which.
How do you reset a Bitzer CM-RC-01 that is locked out?
KT-230-2 lists a Modbus command, BEST SOFTWARE (ALARMS, RESET), switch S2, or disconnecting the L/N supply for at least 5 seconds. For a motor temperature lockout, it says to interrupt the L/N supply for at least 5 seconds; that alarm is excluded from Modbus and BEST SOFTWARE unlocking. Fix the cause first. These steps are from KT-230-2; confirm against your module's edition.
Does the Bitzer CM-RC-01 flash a code?
In the LED sections we reviewed, Bitzer's KT-230 documentation describes the four LEDs as lit, with no flash-code table. The color gives the alarm level, and the BEST SOFTWARE alarm list shows which sensor caused it.
Sources
- Bitzer KT-230-4, Compressor module for reciprocating compressors (CM-RC-01) (section 9.1 operating status LEDs, section 9.2 alarm levels, monitored functions, OLC-D1 and DP-1)
- Bitzer KT-230-2, Compressor module for reciprocating compressors, English edition (section 9 alarm levels; 9.1 to 9.3 automatic reset and unlocking; BEST SOFTWARE alarm list)
- Live product titles for the parts listed above, as shown on each product page
Compressor modules are wired to line voltage, and the compressor and refrigerant circuit operate under pressure. Service should be performed only by qualified personnel, following Bitzer's documentation for your compressor and your facility's lockout/tagout procedures.