California HVAC Controls Systems Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In a large California hospital equipped with a variable air volume HVAC
system, the controls technician observes that multiple terminal boxes
are failing to maintain space temperature during periods of low
cooling demand. The building automation system indicates that
airflow rates at several VAV boxes remain above minimum setpoints
even after cooling calls have ended. Which of the following control
system issues is the MOST likely cause of the problem?
A. Excessive chilled water supply temperature reset
B. Improper static pressure sensor placement near the supply fan
C. Faulty occupancy sensor calibration in patient rooms
D. Low condenser water flow through the cooling tower loop
B. Improper static pressure sensor placement near the supply fan
,Improper placement of a static pressure sensor too close to the supply fan
can cause falsely elevated pressure readings, resulting in the fan slowing
prematurely and preventing downstream VAV boxes from receiving proper
airflow control authority. This commonly leads to terminal boxes
remaining above minimum airflow setpoints and poor zone temperature
regulation.
2. A California office building utilizes demand-controlled ventilation with
carbon dioxide sensors integrated into the building automation
system. During commissioning, technicians discover that outdoor air
dampers remain nearly closed even when conference rooms are
heavily occupied. Which of the following conditions would MOST likely
produce this malfunction?
A. CO2 sensors wired with reversed polarity causing negative readings
B. Supply air temperature reset schedule operating incorrectly
C. Chilled water differential pressure exceeding design limits
D. Condenser fan variable frequency drives operating at minimum speed
A. CO2 sensors wired with reversed polarity causing negative readings
Demand-controlled ventilation systems rely on accurate CO2
measurements to modulate outdoor air dampers. Reversed polarity or
improper sensor wiring can produce invalid or negative readings,
,misleading the controller into assuming occupancy levels are low and
causing ventilation dampers to remain closed.
3. A controls technician troubleshooting a packaged rooftop unit notices
that the economizer damper opens fully during mild weather, yet the
mixed air temperature remains significantly above the outdoor air
temperature. Which of the following conditions is the MOST probable
explanation?
A. Return air damper is stuck partially open
B. Supply fan motor overload relay is undersized
C. Discharge air sensor is mounted downstream of reheating coils
D. Compressor crankcase heater has failed
A. Return air damper is stuck partially open
If the return air damper remains partially open while the economizer
outdoor air damper opens, warm return air continues mixing with outdoor
air, preventing the mixed air temperature from approaching the outdoor
air temperature. This is a common economizer control malfunction.
4. A California university installs direct digital controls throughout a
campus chilled water system. During operation, several field
controllers intermittently lose communication with the supervisory
workstation. Which of the following conditions would MOST likely
cause this issue on an RS-485 communication network?
, A. Excessive network trunk length without repeaters
B. Oversized chilled water balancing valves
C. Low condenser water entering temperature
D. Improper fan belt tension on air handling units
A. Excessive network trunk length without repeaters
RS-485 communication networks have maximum allowable cable lengths.
Exceeding these distances without repeaters or proper network
segmentation can result in signal degradation, intermittent
communication loss, and unreliable controller operation.
5. A technician is calibrating a differential pressure transmitter used to
monitor airflow across a laboratory exhaust fan. The transmitter
output reads incorrectly at both zero pressure and full-scale pressure.
Which of the following actions should be performed FIRST?
A. Replace the building automation controller
B. Verify zero calibration and span adjustment
C. Increase fan motor sheave diameter
D. Adjust chilled water flow through the reheat coil
B. Verify zero calibration and span adjustment
When a differential pressure transmitter reads inaccurately at both ends of
its operating range, technicians should first verify zero and span
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In a large California hospital equipped with a variable air volume HVAC
system, the controls technician observes that multiple terminal boxes
are failing to maintain space temperature during periods of low
cooling demand. The building automation system indicates that
airflow rates at several VAV boxes remain above minimum setpoints
even after cooling calls have ended. Which of the following control
system issues is the MOST likely cause of the problem?
A. Excessive chilled water supply temperature reset
B. Improper static pressure sensor placement near the supply fan
C. Faulty occupancy sensor calibration in patient rooms
D. Low condenser water flow through the cooling tower loop
B. Improper static pressure sensor placement near the supply fan
,Improper placement of a static pressure sensor too close to the supply fan
can cause falsely elevated pressure readings, resulting in the fan slowing
prematurely and preventing downstream VAV boxes from receiving proper
airflow control authority. This commonly leads to terminal boxes
remaining above minimum airflow setpoints and poor zone temperature
regulation.
2. A California office building utilizes demand-controlled ventilation with
carbon dioxide sensors integrated into the building automation
system. During commissioning, technicians discover that outdoor air
dampers remain nearly closed even when conference rooms are
heavily occupied. Which of the following conditions would MOST likely
produce this malfunction?
A. CO2 sensors wired with reversed polarity causing negative readings
B. Supply air temperature reset schedule operating incorrectly
C. Chilled water differential pressure exceeding design limits
D. Condenser fan variable frequency drives operating at minimum speed
A. CO2 sensors wired with reversed polarity causing negative readings
Demand-controlled ventilation systems rely on accurate CO2
measurements to modulate outdoor air dampers. Reversed polarity or
improper sensor wiring can produce invalid or negative readings,
,misleading the controller into assuming occupancy levels are low and
causing ventilation dampers to remain closed.
3. A controls technician troubleshooting a packaged rooftop unit notices
that the economizer damper opens fully during mild weather, yet the
mixed air temperature remains significantly above the outdoor air
temperature. Which of the following conditions is the MOST probable
explanation?
A. Return air damper is stuck partially open
B. Supply fan motor overload relay is undersized
C. Discharge air sensor is mounted downstream of reheating coils
D. Compressor crankcase heater has failed
A. Return air damper is stuck partially open
If the return air damper remains partially open while the economizer
outdoor air damper opens, warm return air continues mixing with outdoor
air, preventing the mixed air temperature from approaching the outdoor
air temperature. This is a common economizer control malfunction.
4. A California university installs direct digital controls throughout a
campus chilled water system. During operation, several field
controllers intermittently lose communication with the supervisory
workstation. Which of the following conditions would MOST likely
cause this issue on an RS-485 communication network?
, A. Excessive network trunk length without repeaters
B. Oversized chilled water balancing valves
C. Low condenser water entering temperature
D. Improper fan belt tension on air handling units
A. Excessive network trunk length without repeaters
RS-485 communication networks have maximum allowable cable lengths.
Exceeding these distances without repeaters or proper network
segmentation can result in signal degradation, intermittent
communication loss, and unreliable controller operation.
5. A technician is calibrating a differential pressure transmitter used to
monitor airflow across a laboratory exhaust fan. The transmitter
output reads incorrectly at both zero pressure and full-scale pressure.
Which of the following actions should be performed FIRST?
A. Replace the building automation controller
B. Verify zero calibration and span adjustment
C. Increase fan motor sheave diameter
D. Adjust chilled water flow through the reheat coil
B. Verify zero calibration and span adjustment
When a differential pressure transmitter reads inaccurately at both ends of
its operating range, technicians should first verify zero and span
