Service manual

Section 7 Refrigeration System
Part No. 80-1100-3 7-27
HARVEST PRESSURE REGULATING
(H.P.R.) SYSTEM
Remotes Only
GENERAL
The harvest pressure regulating (H.P.R.) system
includes:
• Harvest pressure regulating solenoid valve (H.P.R.
solenoid). This is an electrically operated valve which
opens when energized, and closes when de-
energized.
Figure 7-12. H.P.R. Solenoid
• Harvest pressure regulating valve (H.P.R. valve). This
is a non-adjustable pressure regulating valve which
modulates open and closed, based on the refrigerant
pressure at the outlet of the valve. The valve closes
completely and stops refrigerant flow when the
pressure at the outlet rises above the valve setting.
Figure 7-13. H.P.R. Valve
FREEZE CYCLE
The H.P.R. system is not used during the freeze cycle.
The H.P.R. solenoid is closed (de-energized), preventing
refrigerant flow into the H.P.R. valve.
HARVEST CYCLE
During the harvest cycle, the check valve in the
discharge line prevents refrigerant in the remote
condenser and receiver from backfeeding into the
evaporator and condensing to liquid.
The H.P.R. solenoid is opened (energized) during the
harvest cycle, allowing refrigerant gas from the top of the
receiver to flow into the H.P.R. valve. The H.P.R. valve
modulates open and closed, raising the suction pressure
high enough to sustain heat for the harvest cycle,
without allowing refrigerant to condense to liquid in the
evaporator.
In general, harvest cycle suction pressure rises, then
stabilizes in the range of 75-100 psig (517-758 kPA).
Exact pressures vary from model to model. These can
be found in the “Operational Refrigerant Pressures”
charts, beginning on Page 7-32.
SV1427
INLET OUTLET
FLOW
SV3053
OUTLET
INLET