Another constant fan motor

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Old 10-12-13, 05:54 PM
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Another constant fan motor

Hi all,

From Australia. Have a Carrier 58PIN natural gas heater installed, which has decided to run the fan continuously.

The model number may be Australia only. It is a horizontal model, operating on 240volt input. I've tried disconnecting the thermostat (2 wire) but the fan keeps running.

Any help greatly appreciated.

Clive
 
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Old 10-12-13, 06:02 PM
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Welcome to the forums.

I didn't locate any service info on that model.

The blower fan runs continuously.... does the furnace light and make heat ?
 
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Old 10-12-13, 06:06 PM
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Thanks for coming back. The heat side works perfectly. Have replaced a transistor and IC on the fan relay board, to no avail.

Clive
 
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Old 10-12-13, 06:35 PM
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Post the model number of the control board.
 
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Old 10-12-13, 07:22 PM
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two numbers.

BC34571 and FMC0341

Clive
 
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Old 10-13-13, 10:02 AM
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I could not locate any info on your system or the control boards. When you set the thermostat to heat can you explain to us what it is doing, such as, vent motor starts running, pressure switch closes, ignitor comes on, flame present. etc. We need to know how far in the ignition sequence your system gets to. The usual cause of a continuous running fan is either a fan relay with the contacts welded together or an open limit switch (on some models).
 
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Old 10-13-13, 10:43 PM
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The fan operates as soon as the power is connected (240V AC) via the power point. The heating aspect seems to be working correctly.

Clive
 
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Old 10-14-13, 05:26 AM
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Since we can't find information on-line about your unit can you post some photos to give us an idea of what it looks like?
 
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Old 10-18-13, 02:31 AM
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Hopefully these may give a clue
 
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Old 10-18-13, 06:10 AM
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Did you try removing the G wire at the control board to see if the blower will shut off? Do you have an LED error code flashing on the control board?
Have replaced a transistor and IC on the fan relay board, to no avail.
Are you sure replacement of the transistor and IC on the fan relay board repaired that board? Many times a blower that won't turn off is caused by stuck contacts in the blower relay. Another common reason that a blower runs continuously is an open limit switch. You stated the heat side works perfectly. You can take a screw driver handle and tap the relay while the blower is running to see if the relay contacts will unstick.
 
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