Question 7Refrigeration & AC - 1st Asst/Chief

70% to pass

As shown in the illustrated refrigeration system piping schematic diagram with the various accessories and controls and equipped with an air-cooled condenser with high side pressure controls, what statement is true concerning the fan cycling control pressure switch? Illustration GS-RA-39

Refrigeration Chief Question 7 diagram
AWith a condenser fitted with a single fan driven by a multi-speed electric motor, the fan speed would decrease under high ambient temperature conditions.
BWith a condenser fitted with a single fan driven by a multi-speed electric motor, the fan speed would decrease under low ambient temperature conditions.
CWith a condenser fitted with multiple electric-motor driven fans, the number of fans in use would increase under low ambient temperature conditions.
DWith a condenser fitted with a single fan driven by a single-speed electric motor, the fan would cycle off under high ambient temperature conditions.
AI Explanation

The correct answer is B) With a condenser fitted with a single fan driven by a multi-speed electric motor, the fan speed would decrease under low ambient temperature conditions. The reasoning behind this is that in a refrigeration system with an air-cooled condenser, the fan cycling control pressure switch is designed to maintain the proper high-side pressure by adjusting the fan speed. When the ambient temperature is low, the condenser is able to reject heat more efficiently, causing the high-side pressure to decrease. The fan cycling control pressure switch will then reduce the fan speed to prevent the high-side pressure from dropping too low, which could lead to other issues in the system. The other options are incorrect because they do not accurately describe the behavior of the fan cycling control pressure switch in response to changes in ambient temperature. Option A is incorrect because the fan speed would increase, not decrease, under high ambient temperature conditions. Options C and D are incorrect because they do not apply to a system with a single fan driven by a multi-speed motor.

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