If you have a system that has two/three outdoors on the same refrigerant circuit and need to remove one of the units temporarily due to a failure, a few changes will need to be made to the system.
Firstly, you will need to potentially make changes to the transmission wiring to remove the non-operational unit from the network and wire the 'new' master unit in so that the transmission is connected to either X1 X2 (to the indoor units) or Z1 Z2) if there are other refrigerant systems.
For example, if the MASTER unit in the diagram below failed, it might be wired like this
To make it work correctly, electrically disconnect the MASTER unit that has failed, and wire it so the 1st SLAVE is the new MASTER like below
Next you will need to set the DIP switches on the outdoor unit. If there are three outdoor units on one system, the switches will be set as follows
If you electrically disconnect one of the units from the refrigerant system, you will need to change DIP SW3 to suit.
If you have one outdoor unit set the switches as below
Two units
Three units
Once these switches are set, you need to change DIP SW 5 on the NEW MASTER to instruct it on how many SLAVES are connected to it.
If there is one MASTER only
A MASTER and a SLAVE
And when the third unit comes back online again
Finally shut the service valves on the unit that is non operational.