YORK
Start-Up & Operation Guide | 5587001-YSG-A-520
121
Operation
Table 33: Faults List (Continued)
Fault Type
Description
Caused By
Service
Unit continuous runtime exceeds limit
The AHU_AIRFDD_RunContinuous
module is designed to alarm if the unit
runs continuously beyond a defined time
limit. The default is 23 hours. This means
that the unit is not turned off by a time
schedule. If the unit is designed to run
continuously (such as a hospital), then
adjust the alarm_delay to 0 in order to
suppress the alarm
Service
Trim and respond not changing setpoint
The AHU_AIRFDD_SPNotChanging
module is designed to set an alarm if the
setpoint input does not change in value
during the alarm_delay interval. This is
primarily used to make sure that the trim
and respond setpoint adjust features are
working properly. These features are
usually in the supervisory controller
Service
Idle time while occupied exceeds limit
The AHU_AIRFDD_UnitDownInOcc
module is designed to set an alarm if the
unit is shut down for a certain time period
during the occ mode
Service
Economizer not economizing when it should
Economizer damper did not open as
commanded. Damper stuck closed
Service
Economizer economizing when it should not
Economizer damper did not close as
commanded. Damper stuck open
Service
Economizer damper not modulating
Economizer damper did not respond to
a change in the percent open or close
command
Service
Excess outdoor air
Too much outside air is being introduced
into the unit. Outside air damper failure
Service
Space temperature cooling alarm
Space temperature not at expected
temperature within time period
Service
Space temperature heating alarm
Space temperature not at expected
temperature within time period
Service
Airflow detected without supply fan
Airflow indicated when blower expected to
be off. Check APS and/or DPS
Service
Unit has received a purge request
Unit placed in a purge mode by a contact
closure
Service
UV light needs service
UV light module triggers this alarm
Service
Low OAT cooling cutout
OAT is below the cooling lockout setpoint
Service
Heating locked out due to OAT
OAT is above the heating lockout setpoint
Service
Hot water freezestat open to prevent coil freeze
Air temperature at hot water heating coil is
below setpoint
Service
Hot water freezestat open when it should not
Hot water heating coil freeze protection
circuit open with ambient sensor input
above freezing
