York YPAL 060 User Manual

JOHNSON CONTROLS

FORM 100.50-NOM6 (1207)

The Unit Controller compares the supply air temperature 
to the “SUPPLY AIR TEMP ALARM FOR COOLING” 
and initiates the alarm based on the following criteria:

•  All the stages of cooling have been on for 10 or 

more minutes.

•  The supply air temperature is 20 or more degrees 

above the “SUPPLY AIR TEMP ALARM FOR 
COOLING” set point for 10 minutes.

•  The outdoor air is not 20.0° F or more warmer 

then the “SUPPLY AIR TEMP ALARM FOR 
COOLING” set point.

•  The outdoor air damper is not open more then 

20%.

The Unit Controller compares the supply air temperature 
to the “SUPPLY AIR TEMP ALARM FOR HEATING” 
and initiates the alarm based on the following criteria:

•  All the stages of heating have been on for 10 or 

more minutes.

•  The supply air temperature is 20 or more degrees 

below the “SUPPLY AIR TEMP ALARM FOR 
HEATING” set point for 10 minutes.

•  The outdoor air is not 20.0° F or more cooler 

then the “SUPPLY AIR TEMP ALARM FOR 
HEATING” set point.

•  The outdoor air damper is not open more then 

20%.

Prior to declaring this fault the Unit Controller checks the 
outside air temperature and the economizer position.  If 
the outside air temperature is more then 20.0° F warmer 
then the set point and the economizer is open more then 
20%, the Unit Controller will close the economizer for 
10 minutes and then check the supply air temperature.  
If the SAT falls below the set point, the control will 
declare an economizer minimum position alarm.  The 
Unit Controller will keep the economizer closed until 
the end of the cooling cycle.  It will then return the 
economizer damper to its minimum position.

This alarm will be generated based on the following 
criteria:

• The 

“SPACE TEMP TRENDING ALARM TEMP” 

and the “SPACE TEMPERATURE ALARM 
TIME” must be set.

•  The unit has been in a given mode of operation 

for 10 minutes.

•  The temperature is below or above the space 

temperature set point and the trend continues to 
be away from the space temperature set point and 
the “SPACE TEMP TRENDING ALARM TIME” 
has expired.

This alarm is initiated on a VAV unit if after 35 seconds 
of supply fan operation the duct static pressure is not 
equal to or greater then 0.05” WC.  When the alarm 
becomes active the unit stops all operation and locks out.  
This can be the result of a faulty Duct Static Pressure 
Transducer or in the transition from an unoccupied to 
occupied mode if the VAV boxes are wide open.

To check the operation of the duct static transducer 
measure the VDC input between terminal DP+ wire 
337 at the P21 connector and terminal DP- wire 338 
at the P21 connector.  Compare the voltage verses 
the duct pressure the control indicates to Table 8-2 in 
this section of the manual.  Also verify that 24 VAC is 
present between terminals “COM” and “EXC” at the 
duct static transducer.

The alarm indicates the hydronic freeze stat switch has 
opened.  The 24 VAC source originates at the terminal 
FSP, wire 389.  The input to the control originates at 
terminal FSI, wire 388.