HVAC HVAC Troubleshooting Techniques 4

Question 1

A technician recovers refrigerant and finds the system has a deep vacuum after equalization. What does this indicate?

Accepted Answer

The system had a leak and lost most of its charge

Answer

A system that reaches a deep vacuum upon gauge connection has lost refrigerant through a leak, leaving sub-atmospheric pressure inside.

Question 2

A zoned HVAC system heats one zone but fails to condition a second zone. The zone 2 damper motor is receiving 24V. What should the technician check next?

Accepted Answer

Mechanical damper blade for binding or disconnected linkage

Answer

If the actuator has power but the damper does not move, the mechanical damper blade itself may be physically stuck, corroded, or the linkage arm may be detached.

Question 3

A mini-split indoor unit drips water onto the floor during cooling operation. What is the FIRST thing to inspect?

Accepted Answer

Condensate drain line for blockage or improper slope

Answer

Water dripping from a mini-split indoor unit almost always results from a blocked or improperly pitched condensate drain line that causes the drain pan to overflow.

Question 4

Subcooling reads 3°F on a fixed-orifice system operating in 80°F ambient. What condition does this suggest?

Accepted Answer

Low refrigerant charge

Answer

Very low subcooling on a fixed-orifice system indicates insufficient liquid refrigerant in the condenser, which is a sign of a low charge.

Question 5

A gas furnace pressure switch trips on every heating cycle after 10 minutes of operation. The inducer motor amperage is normal. What is the MOST likely cause?

Accepted Answer

Blocked condensate drain causing water to back up into the pressure switch hose

Answer

On high-efficiency condensing furnaces, condensate backing up into the pressure switch hose ports is a frequent cause of nuisance pressure switch trips after initial operation.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC HVAC Troubleshooting Techniques 4