Chapter 12, Problem 6SQ

When the thermostat contacts close, the blower motor does not start. During troubleshooting of the unit, a voltmeter placed across the bottom terminals of the circuit breaker indicates a voltage of 240 volts. When the voltmeter is placed across the secondary of the transformer it indicates a voltage of 24 volts. When placed across the thermostat contacts it indicates 0 volts. When the voltmeter is placed across the coil of CR relay it indicates 24 volts. When the voltmeter is placed across the flow switch contacts it indicates 0 volts. When placed across the coil of HR contactor coil it indicates 0 volts, and when placed across the coil of BMR contactor it indicates 0 volts. Which of the following is the problem?

1. a. CR coil is open.
2. b. BMR coil is open.
3. c. The thermostat is defective.
4. d. The flow switch is defective.