CA C20 HVAC Contractor Exam

CA C20 HVAC Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• What is the primary purpose of a TXV (Thermostatic Expansion

Valve) in an HVAC system?

• To circulate refrigerant
• To regulate refrigerant flow into the evaporator
• To compress vapor
• To remove moisture from refrigerant

Rationale: A TXV adjusts refrigerant flow based on evaporator load,

ensuring proper superheat.

• Which refrigerant is classified as an HFC?

A. R-22

B. R-410A

C. R-717

D. R-290

Rationale: R-410A is a hydrofluorocarbon, replacing R-22 in many systems.

3. The minimum slope for a horizontal condensate drain line is:

• ¼ inch per foot
• 1/8 inch per foot 1 / 3

• 1 inch per foot
• Flat

Rationale: Codes require 1/8” per foot to allow proper drainage.

• What type of compressor is most common in small residential AC

systems?

• Screw
• Scroll
• Centrifugal
• Reciprocating

Rationale: Scroll compressors provide reliability and efficiency for

residential units.

• What is the typical superheat target for a properly charged fixed-

orifice system?

A. 0°F

B. 10–15°F

C. 25–30°F

D. 5°F

Rationale: Fixed metering devices require 10–15°F superheat for optimal

performance.

• Which code governs mechanical installations in California?

A. CBC

B. NEC

C. CMC

D. CRC

Rationale: California Mechanical Code is the primary regulation for HVAC.

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7. Relative humidity is defined as the:

• Total moisture in air
• Moisture content relative to saturation
• Dew point temperature
• Absolute humidity

Rationale: RH compares existing moisture to the maximum possible at that

temperature.

• What tool measures airflow in CFM?
• Manometer
• Anemometer
• Thermistor
• Multimeter

Rationale: Anemometers measure air velocity; combined with area, give

CFM.

• What component absorbs heat in the refrigeration cycle?
• Condenser
• Compressor
• Evaporator

D. TXV

Rationale: The evaporator absorbs heat from indoor air.

10. A cracked heat exchanger can cause:

• Low refrigerant charge
• Carbon monoxide leakage
• Overheating of evaporator
• Compressor burnout
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