Exam 29: Troubleshooting and Typical Operating Conditions for Commercial Refrigeration

The approach of a cooling tower is the ____.

Dirty condenser coils are often the cause for inefficient condensers.

A low refrigerant charge will cause a(n) ____________________ suction pressure, which will increase the compression ratio.

If a system has a(n) ___ for a metering device, the device will try to maintain evaporator superheat even with an excessive overcharge.

High compression ratios will lead to lower compressor discharge temperatures.

Medium-temperature refrigerated cabinet temperatures range from ____.

In a 2-ton TX valve system, the unit does not develop full capacity. Head pressure is high, suction pressure is slightly above normal, and subcooling is below normal. What is the problem?

An air-cooled R-12 refrigeration system is operating normally with a suction pressure of 25 psig and a head pressure of 136 psig. Which of the following represents a possible set of operating pressures if the condenser fan motor burns out?

Will the gauge readings be high or low with a system using a capillary tube that has a low refrigerant charge?

Why is it that many products that require medium-temperature refrigeration will not freeze at 30°F?

For each 12,000 Btu/h capacity, a wastewater-cooled condensing unit uses approximately ____________________ GPM.

In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low and suction pressure is high. What is the problem?

Because of the low refrigerant flow rate through the compressor and the system being undercharged, the 100% saturated vapor point in the condenser will be very low in the condenser, causing low condenser subcooling.

Since many new replacement refrigerants are being used throughout the industry, a technician should rely on system temperatures to ease the troubleshooting process.

In a 2-ton capillary tube system, the unit does not develop full capacity. Head pressure is low and suction pressure is low. What is the problem?

In a high-temperature refrigeration unit, the boiling point of the refrigerant in the coil is normally ____ lower than the cabinet temperature.

A thermostatic expansion valve's capacity will drop if the pressure drop across the valve increases.

Most water-cooling towers can cool the water that supplies the condenser to a temperature within ____________________°F of the wet-bulb temperature of the ambient air.

In a wastewater cooled system, the difference between the condensing temperature of the refrigerant and the leaving water temperature is approximately ____.

For each 12,000 Btu/h capacity, a water-cooled condensing unit and cooling tower combination will circulate approximately ____________________ GPM through the condenser.