Carel AL61

What does Carel AL61 mean?

AL61 means Driver 1 is requesting a go-ahead signal from the main pCO controller but is not receiving it. The go-ahead request is a LAN-based permission mechanism where the expansion valve driver waits for the master controller to authorize valve operation before starting superheat control. Without the go-ahead, Driver 1 holds Circuit 1 offline.

Symptoms

• Circuit 1 remains offline despite normal operating conditions.
• AL61 displays on the controller and requires manual reset.
• Driver 1 is powered and communicating via pLAN but not regulating.
• No other alarm is active on Driver 1 that would explain the shutdown.

Common causes

• LAN communication interruption between Driver 1 and the pCO master controller.
• Incorrect pLAN address configuration on Driver 1 or the pCO.
• Application software on the pCO not configured to issue go-ahead to Driver 1.
• Driver 1 parameters not matching the expected application program configuration.
• Autosetup procedure not completed on Driver 1 (see AL65).

Diagnostic steps

1. 01

   Verify pLAN communication with Driver 1

   Check the pLAN network wiring between the pCO controller and Driver 1. Confirm proper termination resistors are in place and no wiring faults exist.

2. 02

   Confirm Driver 1 pLAN address

   Navigate to Driver 1's network settings and verify its pLAN address matches what the pCO application program expects. Duplicate addresses on the network will prevent communication.

3. 03

   Check pCO application configuration for Driver 1 go-ahead

   Review the pCO application settings to confirm Driver 1 is enabled and the go-ahead output is mapped to the correct network variable.

4. 04

   Complete the autosetup procedure on Driver 1

   If AL65 is also active, complete Driver 1's autosetup first. Navigate to the AUTOSETUP menu on the pCO and run the procedure for Driver 1, confirming valve type, refrigerant, and probe configuration.

5. 05

   Manually reset AL61

   After resolving the go-ahead condition, manually reset AL61 from the pCO alarm menu.

When to call a professional

If pLAN communication faults persist after wiring and address verification, or if the pCO application software requires reconfiguration or reprogramming, contact a Carel-authorized technician. Application software modifications on pCO controllers should only be performed by personnel with Carel c.strategy training.