An air-cooled refrigerated container unit using R-134a as a refrigerant has a box temperature set point of -15 °F, but it is currently operating with a stable return air temperature of 0 °F. The fresh air makeup vent is closed, the unit is operating at 460 VAC/60 Hz, and the unit is in full capacity cool (modulating valve 100% open). Using the illustrated troubleshooting guide, what would be the normal range of expected discharge pressures if the ambient air temperature is 90 °F? GS-RA-52

Illustration GS-RA-52: the U.S. Coast Guard has not released this illustration.

Question

An air-cooled refrigerated container unit using R-134a as a refrigerant has a box temperature set point of -15 °F, but it is currently operating with a stable return air temperature of 0 °F. The fresh air makeup vent is closed, the unit is operating at 460 VAC/60 Hz, and the unit is in full capacity cool (modulating valve 100% open). Using the illustrated troubleshooting guide, what would be the normal range of expected discharge pressures if the ambient air temperature is 90 °F? GS-RA-52

Illustration GS-RA-52: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option D: 150-190 psig. Operating an R-134a container unit with a 90 °F ambient air temperature under full cooling capacity generates standard condensing pressures that fall within the normal operational manufacturer specification range of 150 to 190 psig.