Fan goes on and off constantly(set to on) - http://www.hvacmechanic.com/ Forums
Original message
| bob green
 |  "Fan goes on and off constantly(set to on)"
, posted Mon 21 Jul 12:21:  
I have a 1986 Arcoaire furnace and the problem is the blower motor turns on for a minute then off continuously and consistently. I set the thermostat to off and the fan to on (not auto). It does the same thing. Here is the weird thing, when I have the service access panel open and overide the interlock it runs continuously and when I put the panel back on it goes back to the on/off. I jumpered the door switch to eliminate it as a problem. Keep in mind I am using just the blower motor I also removed the filter to make sure that wasn't it.The a/c is off and was not frozen.
I can spin the motor by hand very easy and the bearings seem good. When I was testing it I used a clamp amp and it was pulling 7.5a and never went up prior to shutting off.
I really appreciate you help.Thanks
[this message was edited by bob green on Mon 21 Jul 12:26] |
| Replies:
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| Freon
|  "Re(1):Fan goes on and off constantly(set to "
, posted Mon 21 Jul 14:29
" I jumpered the door switch to eliminate it as a problem"
Did that solve the problem? If yes, replace the door switch or possibly investigate the switch to see if there's an easy fix. BE SURE to turn off the power to the furnace.
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| | yuri
| "Re(2):Fan goes on and off constantly(set to" , posted Mon 21 Jul 19:48:
Reinforce the door so it is not being sucked in and out and tripping the switch and buy a new switch. Try put a couple of sheet metal screws into the door and cabinet at the sides to hold it steady. Getting parts for that old unit is a challenge (where I am) and the heat exchanger may crack soon due to age. I would look into a 92% efficient newer unit.
Yuri
[this message was edited by yuri on Mon 21 Jul 19:59] |
| | bob green
| "Re(3):Fan goes on and off constantly(set to" , posted Tue 22 Jul 13:03
It wasn't the switch, I jumpered it to take it out of the problem. It still did the same thing with it jumpered. I wasn't clear enough in my post.
I put a new motor and cap in today and so far it's working. I was checking the current draw and it's pulling 9.2a with the filter in or out. The motor is rated 9amp.I hope it's supposed to run at this draw.
Thanks for the quick replies.
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| | yuri
| "Re(4):Fan goes on and off constantly(set to" , posted Tue 22 Jul 13:17
You may have a dirty evaporator coil. Something is overloading the motor and it is from lack of airflow. Removing the door and holding in the switch relieved the suction/load on the fan and that it why it kept running. You may have a collapsed duct/blocked vents or some other obstruction.
Yuri
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