York Millennium YCAJ150, Installation Operation & Maintenance, Page: 66 / 116

66 YORK INTERNATIONAL
ing the system down. The compressor will either be in a
recycling pumpdown or in a pumpdown prior to shut-
down when this message is displayed. The message
will disappear when the compressor shuts off.
“Recycling pumpdown” is initiated while a compressor
is off, able to run, and is in a “No Cooling Load” state. It
can be initiated 45 minutes after either of the following
two conditions are met:
1. Sat Suction Temp > LCHWT - 1.5°F (0.8°C)
and
Ambient Temp > LCHWT - 6°F (3.3°C)
2. The compressor has been idle for 2 hours and Suc-
tion Pressure is greater than the cut-out.
The 45-minute timer assures that excessive pumpdowns
do not occur.
After 120 pumpdowns, uninterrupted by a cooling start,
the system will cease to pump down. Pumpdowns will
begin again after a cooling start occurs. This is to pre-
vent oil loss in the system. However, if one system
reaches 120 pumpdowns while the other system is run-
ning for cooling, the running (lead) compressor will be
shut off if the off (lag) compressor is available for start.
At this point, the lead compressor will pump down and
shut off while the lag compressor starts and assumes
the lead. The previous running compressor will now have
120 pumpdowns available.
S Y S # 1 P U M P D O W N F A I L
S Y S # 2 P U M P D O W N F A I L
A pumpdown failure fault will occur if a system performs
3 unsuccessful pumpdowns in a row. “Unsuccessful”
assumes that the system was not able to pump down to
the suction pressure cut-out in 3 minutes. The system
will require a manual reset to restart. The following is an
example of this safety message.
NOTE: Under some circumstances, a pumpdown may
occur when a compressor is called to come on
for cooling. If this occurs, the compressor will
restart to provide cooling after the pumpdown is
complete and the anti-recycle timer times out.
Recycling pumpdown will increase the number of starts
logged in the micropanel; however, it will have no effect
upon the life of the compressors.
Pumpdown Safety
The Pumpdown Safety assures that a compressor does
not run unless it completes a proper pumpdown. This
prevents operation of a refrigerant system which has a
leaking liquid line solenoid valve.
On shutdown, the system must pump down to the suc-
tion pressure cut-out within 300 seconds or the system
will shut down. If the system performs 3 unsuccessful
pumpdowns in a row, the system will fault and lockout.
An example of the Pump down fault display message is
shown below.