Back Pressure Valve - Carrier CMCT Series Service & Installation Manual

BACK PRESSURE VALVE – #1
These models are equipped with a back pressure
valve. The purpose of this valve is to limit the suction
pressure at the compressor during initial cabinet start
up and start up after a defrost cycle. This valve is set at
10 PSIG and should not be changed. To check this
setting it is necessary that the pressure on the inlet side
or evaporator side of the valve be above 10 PSIG. Put
cabinet into defrost cycle to obtain high-low side pres-
sure. With gauge installed on suction service valve,
check valve setting after cabinet comes off the defrost
cycle. Allow the compressor to run a few minutes before
determining correct setting. (CRO6 shown)
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28 MAINTENANCE & REPAIR