York YPAL 050, YPAL 061 Supply Air Temperature Sensor Alarm, Return Air Temperature Sensor Alarm

Supply Air Temperature Sensor Alarm (20)

This alarm indicates the supply air temperature input is either open or shorted. The display will show a value of –40.0° F. The supply air temperature input is at SAT+ and SAT- of the P11 connector. To trouble shoot compare the resistance of the input to the actual supply air temperature using Table 8-1.

Return Air Temperature Sensor Alarm (21)

This alarm indicates the return air temperature input is either open or shorted. The display will show a value of –40.0° F. The return air temperature input is at RAT+ and RAT- of the P11 connector. To trouble shoot compare the resistance of the input to the actual return air temperature using Table 8-1.

Outdoor Air Temperature Sensor Alarm (22)

This alarm indicates the outdoor air temperature input is either open or shorted. The display will show a value of –40.0° F. The outdoor air temperature input is at OAT+ and OAT- of the P11 connector. To trouble shoot compare the resistance of the input to the actual outdoor air temperature using Table 8-1.

Dirty Filter Switch Alarm (23)

This alarm will have no effect on the operation of the unit. The alarm indicates the dirty filter switch contacts have closed indicating the pressure drop across the filters is above the setting of the switch. The 24 VAC output to the switch is at terminal FILT wire 391 of the P22 connector and the input to the control is at terminal FILT wire 390 of the P22 connector.

Supply Fan Air Proving Switch (24)

This alarm indicates there was a call for supply fan operation and after 90 seconds of supply fan operation the switch did not close. The Unit Controller will retry the fan output every 30 minutes for three retires. If after the three retries the Unit Controller will lockout heating and cooling operation.

On a VAV unit the Unit Controller will also use the duct static pressure input to qualify supply fan operation. If the Unit Controller reads more then 0.05" WC it will continue to identify the alarm but allow the unit to operate.

FORM 100.50-NOM6 (1207)

The 24 VAC output to the switch is at terminalAPS wire 412 of the P11 connector and the input to the control is at terminal APS wire 411 of the P11 connector.

Supply Fan Air Proving Switch Closed Alarm (25)

This alarm indicates the call for supply fan operation has been terminated and after 90 seconds of supply fan operation the switch remained closed. The control will flash the alarm but allow the unit to operate normally.

The 24 VAC output to the switch is at terminalAPS wire 412 of the P11 connector and the input to the control is at terminal APS wire 411 of the P11 connector.

Microelectronics Failure Alarm (26)

This alarm indicates a problem with the Unit Controller microelectronics has occurred and the Unit Controller is operating on default values. Try recycling power to the control. If the fault reappears replace the Unit Controller.

Microelectronics Failure Alarm (27)

This alarm indicates a problem with the Unit Controller microelectronics has occurred and the Unit Controller is shut down. Try recycling power to the control. If the fault reappears replace the Unit Controller.

Supply Fan Overload Alarm (28)

The Unit Controller monitors this circuit anytime the supply fan is operative. If this input is lost for 50 milliseconds, the control will shut down all unit operation. If the voltage input does not return in 5- minutes the control will turn on the alarm.

If the voltage returns the Unit Controller will log the first incident and track the run time. If the switch opens three times in a two-hour period the Unit Controller will shut down the unit.

The 24 VAC output to the switch is at terminal FOVR wire 404 of the P16 connector and the input to the control is at terminal FOVR wire 403 of the P16 connector.

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JOHNSON CONTROLS 165