CFC Automotive Air Conditioning Service 4

Question 1

What does a sight glass in an automotive A/C system that shows bubbles while the compressor is running typically indicate?

Accepted Answer

Low refrigerant charge

Answer

Bubbles in the sight glass indicate incomplete liquid flow to the expansion valve, most commonly caused by low refrigerant charge.

Question 2

R-134a must NOT be mixed with R-12 because:

Accepted Answer

They are incompatible — different oils are used and mixing creates unsafe pressures and deposits

Answer

R-134a uses PAG oil while R-12 uses mineral oil; mixing refrigerants causes chemical incompatibility, pressure irregularities, and can damage system components.

Question 3

When transferring refrigerant from a recovery cylinder to a charging cylinder, the technician should:

Accepted Answer

Weigh the refrigerant and transfer at room temperature using appropriate hoses

Answer

Refrigerant transfer between cylinders must be done gravimetrically (by weight) using proper hoses at ambient temperature — open flames near refrigerant cylinders are dangerous.

Question 4

An automotive technician discovers an A/C system contains R-12. To legally service this system they must:

Accepted Answer

Use only Section 609-certified equipment and a technician certified for CFC refrigerants

Answer

R-12 is a Class I ODS refrigerant; servicing requires Section 609-certified technicians using approved recovery equipment rated for CFCs.

Question 5

The compressor clutch engages but the A/C system produces no cooling. Low-side pressure is very high and high-side pressure is near low-side pressure. This indicates:

Accepted Answer

Compressor internal failure (not pumping)

Answer

Equal pressures on both sides with the compressor engaged indicate the compressor is spinning but not pumping — an internal mechanical failure.

(CFC) Chlorofluorocarbon Certification Practice Test

(CFC) Chlorofluorocarbon Certification Practice Test

CFC Automotive Air Conditioning Service 4