Air Conditioning Repair Refrigeration System Repair 3

Question 1

What does a high subcooling reading combined with high discharge pressure most likely indicate?

Accepted Answer

Non-condensables in the system

Answer

Non-condensables such as air in the system raise discharge pressure and subcooling because they occupy condenser space without condensing.

Question 2

When recovering refrigerant from a system, the technician must use equipment certified to which standard?

Accepted Answer

SAE J2788

Answer

SAE J2788 certification is required for refrigerant recovery/recycling equipment used on motor vehicle AC systems; EPA Section 608 requires similar certification for stationary systems.

Question 3

A tech notices the evaporator coil is freezing up only at the inlet. What is the most likely cause?

Accepted Answer

Metering device feeding too much refrigerant

Answer

When the metering device feeds excessive refrigerant, it floods the evaporator inlet, causing ice formation at the entry point where liquid refrigerant accumulates.

Question 4

What is the minimum evacuation level (microns) typically required before recharging a residential air conditioning system?

Accepted Answer

500 microns

Answer

Industry standard requires pulling the system down to 500 microns or below to ensure adequate moisture and air removal before charging.

Question 5

A compressor has a burnt motor winding. After replacing it, what additional step is critical before restarting?

Accepted Answer

Flushing the system to remove acid and debris

Answer

A burnt motor leaves acid contamination that must be flushed out and a liquid-line suction filter-drier installed to prevent damage to the new compressor.

Air Conditioning Repair Practice Test

Air Conditioning Repair Practice Test

Air Conditioning Repair Refrigeration System Repair 3