CRST Installation & Maintenance Practices 2

Question 1

When installing a condensing unit outdoors, what minimum clearance is typically required on the air discharge side?

Accepted Answer

24 inches

Answer

Most manufacturers require at least 24 inches of clearance on the discharge side to prevent recirculation of hot condenser air.

Question 2

Which refrigerant line on a split system should be insulated to prevent condensation and heat gain?

Accepted Answer

Suction line only

Answer

The suction line carries low-pressure, low-temperature refrigerant vapor and must be insulated to prevent heat gain and condensation.

Question 3

What is the purpose of a crankcase heater on a refrigeration compressor?

Accepted Answer

Prevent refrigerant migration into compressor oil during off cycles

Answer

Crankcase heaters keep the oil warm to prevent refrigerant from migrating and diluting the compressor lubricant during the off cycle.

Question 4

A technician is installing copper refrigerant tubing and needs to make a brazed joint. What gas should be used to purge the line during brazing?

Accepted Answer

Dry nitrogen

Answer

Dry nitrogen purging during brazing prevents internal oxidation scale that can clog metering devices and damage compressor valves.

Question 5

After installing a new refrigeration system, what is the recommended procedure before charging with refrigerant?

Accepted Answer

Pressure test with nitrogen, then evacuate to 500 microns or below

Answer

The system should be pressure tested with dry nitrogen to check for leaks, then evacuated to 500 microns or lower to remove air and moisture before charging.

(CRST) Certified Refrigeration Service Technician Practice Test

(CRST) Certified Refrigeration Service Technician Practice Test

CRST Installation & Maintenance Practices 2