In this scenario, a legacy N2 controller fails, either electronically or mechanically. The customer needs to replace just one controller. Consider the following options:
Replace the legacy N2 controller with an N2-capable equipment controller configured for N2. See Applying N2-capable Equipment Controllers as replacements for legacy Controllers for the key challenges to this option.
You may find Option 1 too challenging or not cost effective for just one controller. If so, consider finding a direct replacement. All legacy N2 controllers are no longer in production; however, you may find direct replacements through sources other than new production. For example, you may find a direct replacement in the truck inventory of a service technician or through a Johnson Controls distributor who has an inventory of legacy N2 controllers. Also, the Johnson Controls Repair Center has an inventory of refurbished legacy N2 controllers, as they offer repair and return capability for these devices.
If the failed controller is used in a critical application and the situation is extremely time-sensitive, then you should consider moving a similar controller if available from a less critical application and temporarily using it as a replacement. Then implement either Option 1 or 2 when time permits.