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Service practice questions

34 questions from the epa 609 (vehicle a/c) practice test.

Service practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

After the recovery machine pulls the system into a vacuum and shuts off, the procedure calls for waiting about 5 minutes. If the system pressure then rises above zero, the technician should

  1. begin the repair, since the rise is only air
  2. vent the remaining pressure to the shop exhaust
  3. run the recovery again until the vacuum holds
  4. add a small charge to push the residue out
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C. run the recovery again until the vacuum holds

A pressure rise means refrigerant is still boiling out of the oil and cold components. Recovery is repeated until the system stays in a vacuum for a couple of minutes.

Reference: SAE J2211; SAE J1989

Why does system pressure often climb back up a few minutes after recovery has pulled it into a vacuum?

  1. Outside air is being drawn through the service hoses
  2. The compressor clutch has re-engaged on its own
  3. The recovery machine is pushing vapor back in
  4. Refrigerant is still boiling out of the oil
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D. Refrigerant is still boiling out of the oil

Refrigerant dissolved in oil, or trapped in a chilled accumulator, vaporizes slowly as parts warm up. That is why a single pull-down often leaves refrigerant behind.

Reference: SAE J2211; SAE J2788

The main purpose of evacuating a system with a vacuum pump before charging is to remove

  1. air and moisture
  2. oil and dye
  3. metal particles
  4. old refrigerant liquid
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A. air and moisture

A deep vacuum removes air and boils off moisture. It does not remove oil or solid debris; those need draining, flushing or component replacement.

Reference: SAE J2211; EPA Section 609 training

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