I have a customer that has a few Carrier 50AK 50 ton units that were built in 2003. These do not have any type of Carrier controller on them. We are using a JCI UNT to control these and are resetting the supply air temperature based on the return air temp and then increasing or decreasing the temp through a reset board in the unit that accepts a 4-20mA signal. There is a microprocessor board on the unit that seems to control everything internal to the unit (unloaders, economizer etc.). This board drives us nuts because it's like it has a "mind of it's own" and we have no access to it. When the units were first installed, a guy from the Carrier rep came by a few times and had some DOS based software on a calculator/keyboard "minicomputer". He indicated that he was one of the only people that had that software. He did saw we could buy it but we never did.
Can someone tell me what we can to in order to move into the "90's" let alone the millennium with these units. I would like to find a way to put something on these so we gather the data out of the units so we know what's going on. It does appear to have a plug in CCN connection.