fan runs backwards-again

Questions about repairs and parts for Coleman furnaces, air conditioners and heat pumps for manufactured homes. Click here for Coleman parts.

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richnchicks
Posts: 7
Joined: Sat May 16, 2009 10:54 am

I have a coleman 3500a816. about a year ago i replaced: the disconnect, sequencers, thermostat, transformer, fan relay, all fuses, all wires, fan motor and capacitor. it has run flawlessly all year on both heat and cool. the reason for replacement was fan ran backwards and on inspection, many wires were burned and disconnect was burned through and there were jumpers and it had been rewired somewhat shabbily to say the least! i bought the diagrams from you and rewired the entire unit to specs. yesterday the motor started running backwards again. today i replaced the capacitor but no help. the parts house was out of motors until next monday or that would have been replaced as well. my question is, is it normal for the motor to be damaged to the point of no return if the cap goes bad? inspection showed NO burned wires or connectors and disconnect looks the same as when i installed it a year ago. thanks for a really great website. Rich
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Robert
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Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Hi Rich,


Would best to call an hvac tech out to inspect the furnace and diagnose the problem.


A run cap going bad can cause motor to run backwards.


Whether or not that would damage motor would depend on motor, length of time running backwards, etc.



Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?
richnchicks
Posts: 7
Joined: Sat May 16, 2009 10:54 am

Robert,
sorry for the long delay. been a busy year to say the least! found where a water leak had gone into the motor. replaced motor and new cap and has been working fine since. today i had a tech come out for no cooling and he found a leak outside. he said to braze the line, it's easy to get to, and recharge would be $650.00. don't know if that's normal but it's a bit much for me right now. he was willing to sell me a new unit though! actually he was a really nice guy and was limited by company policy. soooo, since it is basically "shot" i have to get window a/c's for now. oh, almost forgot, i have the fan running just to circulate the air. only 99 inside now! guess i could braze it myself. have done it years ago when i was in the service. no freon left in the system now. are there any laws or restrictions about doing it myself? i would then have a tech come out and check it.
thanks for all your help. i really enjoy reading all these hints. you amaze me with your knowledge!
rich
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Robert
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Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Hi Rich,

$650.00 is overkill in my humble opinion. You can braze all you want and anything else except charging it up.


What is shot ? Why is it shot ?


Need to bleed nitrogen through lines while brazing and then pressurize with nitrogen to test for leaks.



Thanks,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?
richnchicks
Posts: 7
Joined: Sat May 16, 2009 10:54 am

Hi Robert,
sorry, the "shot" is from me not willing to put $650 into brazing and recharging. so far i've had 3 techs from 2 different companies who were more interested in selling me a new system than fixing this one. the first 2 swore the heating side was beyond fixing, yet, with your help i was able to get the wiring diagram and the heater works perfect. i spent a total of about $275 for all the parts.
i retired from IBM as a customer engineer, was a helicopter and fixed wing mechanic for 10 years in the service and attended electronics school for a while before going into the service. you are the only one who has really been willing to help me fix this unit. you can't imagine how much i appreciate your help. my expertise isn't in hvac but i'm "humbly grateful" yours is!
I have 2 window units now so i can take some time to get the central unit fixed. it's hard for me to work in 100+ degrees these days so it takes longer.
thanks again,
rich
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Robert
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Posts: 6413
Joined: Wed Feb 28, 2007 12:07 am
Location: Tennessee

Hi Rich,


You're very welcome, happy to help. I rarely if ever advice a customer to replace an electric furnace.


Take your time, 100+ days are killer on me as well. Turned 50 in June and have diabetes and heart disease, plus retired from law enforcement on disability from a neck/spine/back injury.

Add in 30 years of doing hvac this month and my body is sounding off loud and clear these days.


Take care and best wishes,
Robert
Some people are Humbly Grateful, while some are Grumbly Hateful.................... Which one are you ?
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