Service
24 VAC power is supplied to the compressor protection module for compressor 2A from wire 443 at terminal C30 of the P12 connector. The binary input back to the Unit Controller from the compressor protection module is wire 442 at terminal C30 of the P12 connector.
24 VAC power is supplied to the compressor protection module for compressor 2B from wire 445 at terminal C40 of the P12 connector. The binary input back to the Unit Controller from the compressor protection module is wire 444 at terminal C40 of the P12 connector.
Low Pressure Cutout Alarm (09, 10, 11, 12)
Since tandem compressors are used there is a single low pressure switch for system 1 and one for system 2. If the low pressure switch opens both of the compressors for that system will be turned off. If the low pressure switch for system 1, (compressors 1A, 1B), opens it will generate both a 09 and 10 alarm code. Likewise if the low pressure switch opens for system 2, (compressors 2A, 2B), opens it will generate both an 11 and 12 alarm code.
The low pressure switch opens at 50 PSIG and closes at 71 PSIG. In order to generate a low pressure lockout the high pressure switch must open three times within a 2 hour window.
During the start up of the compressor system the low pressure switch input is ignored for 30 seconds. After the 30 second delay if the low pressure switch circuit opens for 5 seconds the Unit Controller will turn off both compressors for the system.
24 VAC power is supplied to the system 1 low pressure switch circuit from wire 395 at terminal LPS1 of the P15 connector. The binary input back to the Unit Controller from the low pressure switch is wire 396 at terminal LPS1 of the P15 connector. The above input is then jumpered to terminal LPS2 of the P15 connector.
24 VAC power is supplied to the system 2 low pressure switch circuit from wire 433 at terminal LPS3 of the P16 connector. The binary input back to the Unit Controller from the low pressure switch is wire 434 at terminal LPS3 of the P16 connector. The above input is then jumpered to terminal LPS4 of the P16 connector.
FORM
Limit Switch Alarms (13, 14, 15)
The control monitors the limit switch status for each of the heating sections installed. If the limit switch circuit opens the control
In order to generate a limit lockout the limit switch must open three times within a
The limit input for heat section 1 is located at terminal LIM1 wire 507 of the P10 connector. The limit input for heat section 2 is located at terminal LIM2 wire 522 of the P10 connector. The limit input for heat section 3 is located at terminal LIM3 wire 533 of the P10 connector.
Gas Heating Alarms (16, 17, 18)
The Unit Controller monitors the output to the gas valve. If the Unit Controller is calling for the operation of the heat stage and voltage is not present after 5 continuous minutes it will generate an alarm.
If the Unit Controller is not calling for the operation of the heat stage and voltage is present at the gas valve for 5 continuous minutes it will generate an alarm and lock on the supply fan. If the input goes away the control will revert to normal operation.
The gas valve input for heat section 1 is located at terminal GV1 wire 510 of the P10 connector. The gas valve input for heat section 2 is located at terminal GV2 wire 525 of the P10 connector. The gas valve input for heat section 3 is located at terminal GV3 wire 536 of the P10 connector.
Space Temperature Sensor Alarm (19)
This alarm indicates the space temperature input is either open or shorted. The display will show a value of
164 | JOHNSON CONTROLS |
