Purge Mode - Model 30 And 50 Units Only - Ingersoll-Rand Thermo King V-520 Series Maintenance Manual

Purge Mode - Model 30 and 50 Units
Only
When the temperature falls a pre-determined
number of degrees below the setpoint
temperature, the controller prepares the unit for
the Heat mode by placing the unit in the Null
mode for 10 seconds, and then placing the unit in
the Purge mode for 45 seconds before shifting to
the Heat mode. In the Purge mode the compressor
clutch is energized but the evaporator fans are not.
This moves the refrigerant from the condenser to
the low side to increase the heating capacity. See
Figure 6 below.
CONDENSER BLOCKING SOLENOID
COOL/PURGE MODE
Figure 6: Model 30 Refrigerant Flow in Cool and Purge Modes
NOTE: The unit will not go into the Purge mode
when coming out of the Null mode because it
reached setpoint. The unit will only go into the
Purge mode when first going into the Heat mode
because the unit is powering up or when going
directly from the Cool mode to the Heat mode.
NOTE: The following diagram shows a Model
30 unit. Purge mode in a Model 50 unit is
similar.
General Description
ARA2041
27