Small appliance service: EPA 608 Practice Questions

Which of these refrigerants is used in most new household refrigerators sold in the United States today?

Most new US household refrigerators use isobutane (R-600a). Older units commonly use R-134a, and much older ones R-12.

A 1985 refrigerator still in service most likely contains which refrigerant?

Refrigerators of that era used R-12, a CFC. It must be recovered, and recovered R-12 should be kept separate from other refrigerants.

A small appliance has a restricted capillary tube. Which symptom is most likely?

A restriction starves the evaporator, so suction pressure drops and cooling is poor, much like a low charge.

A technician who holds only Type I certification wants to buy a 12-oz can of R-134a for a refrigerator repair. Is the sale allowed?

Any Section 608 certified technician (Type I, II, III or Universal) may buy regulated refrigerant.

After repairing a leak in a small appliance, how should the repair be checked before evacuation?

A nitrogen pressure test with bubble solution confirms the repair. Never use oxygen or compressed air.

Why should a small appliance be evacuated before it is recharged after a sealed-system repair?

Air and moisture cause high pressures, acid and capillary-tube freeze-ups. Evacuate with a vacuum pump, then weigh in the charge.

A technician recovers R-134a from a refrigerator into a cylinder that already holds recovered R-12. What is the problem?

Mixed refrigerants usually cannot be reclaimed and may have to be destroyed. Use a separate, labeled recovery cylinder for each refrigerant.

A refrigerator's evaporator shows frost on only the first few passes, and the box is warm. What is a likely cause?

With too little refrigerant, it all boils off in the first part of the evaporator, leaving partial frost and poor cooling. Find and fix the leak before recharging.