102
TK 56430-18-IP-EN
Section 13 - Unit Performance Adjustments
Overview
Various models of vehicle powered truck units are equipped with either a Suction Pressure Regulator (SPR) valve or a
Compressor Pressure Regulator (CPR) valve. After unit installation, these valves require adjustments for maximum
performance. Conditions such as high or low ambient temperatures or the voltage option selected, may require that the
settings be fine-tuned for optimum performance. Adjustment procedures can be found in the unit specific installation
manuals. The table (
) shows which units have these valves.
D
De
effiin
niittiio
on
nss o
off S
SP
PR
R a
an
nd
d C
CP
PR
R V
Va
allv
ve
ess
S
SP
PR
R V
Va
allv
ve
ess:: SPR valves are used to regulate the current draw on the electric standby motors by limiting pressure
going into the compressor and in turn limiting the load on the compressor.
C
CP
PR
R V
Va
allv
ve
ess:: On vehicle powered truck units, the CPR valves have two main purposes. First, a CPR valve is required for
hot gas heat operation. During a hot gas heat cycle, the compressor must create a pressure differential. Because the
expansion valve is being bypassed, the CPR valve is used to drop the pressure so the compressor can function properly.
Failure to properly set the CPR valve on units with hot gas heat will result in a reduction of heat capacity. Secondly, on
multi-temperature units, the CPR valve is used for zone-priority / zone-control. When both fresh and frozen zones are
requiring cooling, the fresh box suction pressures are much higher due to the higher box temperature, and will always
use the majority of the refrigerant. The CPR valve is used to drop the suction pressure of the fresh evaporator, when the
frozen is requiring cooling, to match the frozen zone’s suction pressure allowing both zones to cool simultaneously. If
the Spectrum unit’s CPR valve is not set properly, the frozen zone will not cool until the fresh zone has reached setpoint.
F
FA
AIIL
LU
UR
RE
E T
TO
O A
AD
DJ
JU
US
ST
T T
TH
HE
ES
SE
E V
VA
AL
LV
VE
ES
S M
MA
AY
Y N
NO
OT
T A
AL
LL
LO
OW
W T
TH
HE
E U
UN
NIIT
T T
TO
O O
OP
PE
ER
RA
AT
TE
E A
AT
T IIT
TS
S M
MA
AX
XIIM
MU
UM
M C
CA
AP
PA
AC
CIIT
TY
Y..
Table 11.
VP Truck Units with SPR or CPR Valves
VP Model
SPR
CPR
VP Model
SPR
CPR
V-200/V-300 10
V-520 NM SPECTRUM 10 MAX
X
V-200/V-300 20
V-520 NM SPECTRUM 20 MAX
X
V-200/V-300 10 MAX
V-520 NM SPECTRUM 50 MAX
X
V-200/V-300 20 MAX
X
V-520 RT 10/10 MAX
V-220/V-320 10
V-520 RT 20/20 MAX
X
V-220/V-320 20
V-520 RT 30/30 MAX
X
V-220/V-320 20 MAX
X
V-520 RT 50/50 MAX
X
X
V-220/V-320 30
X
V-520 RT SPECTRUM 50 MAX
X
X
V-220/V-320 50
X
V-800 10 MAX
X
V-520 NM 10/10 MAX
V-800 20 MAX
X
V-520 NM 20/20 MAX
X
VM-405 MAX EL
X
V-520 NM 30 MAX
X
VM-405 PBBD2
V-520 NM 50 MAX
X
X
