EPA 609 Leak Detection & System Diagnosis 2

Question 1

On a properly charged R-134a MVAC system at idle with moderate ambient temperature, typical low-side gauge pressure should be approximately:

Accepted Answer

25–45 psi

Answer

A properly functioning R-134a system typically shows 25–45 psi on the low (suction) side at idle, reflecting normal evaporator operating pressure.

Question 2

Abnormally HIGH high-side pressure in an MVAC system most commonly indicates:

Accepted Answer

A blocked or inoperative condenser or cooling fan

Answer

When the condenser cannot reject heat efficiently due to blockage or fan failure, high-side pressure rises as the refrigerant cannot condense properly.

Question 3

Abnormally LOW high-side pressure combined with abnormally LOW low-side pressure most likely indicates:

Accepted Answer

Insufficient refrigerant due to a system leak

Answer

Low pressure on both sides is the classic signature of an undercharged system, typically caused by refrigerant loss through a leak.

Question 4

A compressor clutch that rapidly cycles on and off (short-cycles) at higher than normal frequency typically indicates:

Accepted Answer

A low refrigerant charge triggering the low-pressure cutout switch

Answer

When refrigerant charge is low, suction pressure drops quickly, causing the low-pressure cutout switch to cycle the compressor off repeatedly before pressure can stabilize.

Question 5

A 'bubbling' or 'gurgling' sound heard from the liquid line sight glass (where equipped) indicates:

Accepted Answer

Bubbles of refrigerant vapor in the liquid line, suggesting low charge or a restriction

Answer

Bubbles in the sight glass indicate the liquid line contains refrigerant vapor, which means the charge is insufficient or there is a restriction reducing pressure upstream.

EPA 609 - EPA Section 609 Refrigerant Certification Practice Test

EPA 609 - EPA Section 609 Refrigerant Certification Practice Test

EPA 609 Leak Detection & System Diagnosis 2