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Symptom: Fan (circulating blower) not running
о Potential causes:
◊ High-voltage (120 V) supply issue
• Door switches could be breaking contact.
◊ Signal issue
• Controller could have found a problem during boot-up checks.
• Signal could not be reaching the circulating blower (possibly due to equipment failure).
о Troubleshooting:
◊ Eliminate all other calls (remove wires from W, G, Y1, and Y2 terminals)and remove the front cover from the
GF200 Controller (Part No. 85566), revealing the circuit board. Ensure the GF200 is at idle before proceeding.
◊ Apply a jumper between R and G while monitoring the exposed circuit board of the controller.
• Does the 'G' status LED ( [LED4], below connector 'C') light up when the jumper is connected?
• If YES, check that the FAN Status LED ( [LED10], bottom right) is ON.
• If YES, check for 120 V AC at the fan (5-position connector). Black wire should be 'hot' relative to
ground (green). BE SURE to make the door switch after removing the door to access the fan.
• If YES, check for PWM signal at the fan (16-position connector). Look for 1 – 5 V DC
between black and green (during an active fan demand).
• If YES, consider replacing Motor Control Module
• If NO, repeat check for PWM signal at the Controller (connector 'F'; 6-position)
• If YES, replace Fan Control Harness (contact Technical Support)
• If NO, consider replacing Controller (p/n: 85566)
• If NO, check for 120 V AC at all door switch terminals (also check that switches are making).
• If 120 V AC is not present at any door switch terminal, trace wire back to panel, checking for
voltage at any connection point.
• If NO, check 3-way valve (rainbow) harness (connected to left side of Controller) for faults.
• If any wires with intact crimp terminals are found to be loose, reinsert them (audible click).
• If any wires with bare ends are loose, the harness must be replaced.
• To check communication to the 3-way valve:
• Power-cycle the Controller (disconnect connector 'A'; top left; 2 wires – blue and black)
• Plug in connector 'A' while keeping a hand on the 3-way valve motor's white plastic body.
• Feel for the motor's steady hum (approx. 3 sec.), pause, and return hum.
If these steps fail to resolve the error, contact NTI Technical Support for further assistance.
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