SUMMARY
This article describes how to replace the microprocessor in your legacy chiller system.

SYMPTOMS
After performing a chiller microprocessor controller replacement on a dual state "D Series" chiller the second stage programming functions are not showing up in the programming mode.

CAUSE
By default, legacy replacement microprocessors are shipped configured for single "S Series" stage operation

RESOLUTION
When field installing a replacement microprocessor controller on a dual stage unit, the controller needs to me setup for dual stage operations.

The following steps will get your into the "Factory" programming mode to set up the controller for dual stage operation:

1. From the normal running mode, press and hold the "UP" and "SYS Pump" buttons for 3-5 seconds. Be sure to press both buttons at the same time firmly.

2. When the controller goes into the Factory programming mode you will see "CFG" in the top screen. Note: This will look like a "CF6".

3. Press set TWO times until you see "CP" in the top screen and a "1" in the bottom screen. Using the "Up" or "Dn" button change the CP value in the bottom screen from 1 to 2.

4. Once the CP value has been changed, hit the "Set" button approximately nine more times until you see a "UPD" in the top screen. Once you see "UPD" press the set button one more time and the screen will flash indicating the CP change you made has been saved into the controllers memory.

You have now configured the controller for dual stage operation. It is recommended that you go into the standard configuration mode to complete programming for your site conditions.

APPLIES TO
All Legacy models with microprocessor controllers