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NO MAKE-UP AIR
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- Are the make-up air dampers open?
- Will the damper blade move freely?
- Does the ductwork block the blade?
- Is the make-up air fan running?
- 208/3 phase fans have reset switches on their starters.
- Check the circuit breaker panel.
- Check the disconnect switch on the fan.
- Check belt on fan.
- Check the ductwork for:
- Flex duct in make-up air ductwork.
- Excessive number of elbows.
- Leaks.
- Check make-up air fan unit filters for cleanliness.
- Is the fan running in the right direction?
- Check the rotation arrow on the fan.
- 3 phase motors reverse direction by interchanging any 2 leads.
- 1 phase motors have wiring instructions printed on the motor.
- Fire system - If the fire system has not been armed, the microswitch may
be keeping the make-up air fan "off". A Fire System Distributor must arm
the unit before the fan will work.
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NO EXHAUST
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- Is the exhaust fan running?
- 208/3 phase fans have reset switches on their starters.
- Check the circuit breaker panel.
- Check the disconnect switch on the fan.
- Check belt on fan.
- Is the fan running backwards?
- Check the rotation arrow stamped on the fan.
- 3 phase motors reverse direction by interchanging 2 leads.
- 1 phase motors have wiring instructions printed on the motor.
- Is the correct fan over the correct hood?
- Check the ductwork for:
- Squared elbows.
- Excessive number of elbows.
- Leaks.
- Are the filters damaged?
- Dirty.
- Bent.
- Missing.
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MOTOR CYCLES ON AND OFF
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- Check amperage, make sure it is below the FLA rating.
- Flue gas equipment under backshelf hoods with short exhaust
ducts can cause exhaust fans to cycle due to automatic
thermally protected motors. Change to manual reset switch
motor with class B insulation.
- If fan is near a heat source on the roof, i.e., refrigerator
compressor, motor may cycle.
- Motor may be wired for 115V/1 phase instead of 208V/1 phase
and vice versa. This will also cause the fan to cycle.
- Circuit breaker may be undersized and tripping out.
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