From: John De Armond
Subject: Re: Roof Air Problems - help please
Date: Thu, 06 Oct 2005 13:22:18 -0400
On Wed, 5 Oct 2005 16:20:47 -0400, "Doug MacArthur"
>I have a Duotherm Brisk Air roof air conditioner on a 2004 Class C. It won't
>work when it's important to me that it should work. It only works when I
>don't need it or when I take it into the service guy (twice) to get the
>problem fixed.. Service guy can't find anything wrong.
>When it doesn't work I get a constant level hum at low, med and high fan but
>the fan won't start. The compressor will start. The wiring has been checked
>for bad connections.
>Any suggestions appreciated.
That says something about the qualifications of the service guys. Your
symptoms automatically point to "worn out fan motor bearings and/or
When the fan won't start, reach up in there and try to turn the fan
with the power off. If the shaft is stiff, the oil has congealed.
Most of these have an oiling port, sometimes extending through the
housing and sometimes only accessible through a hole in the case. Find
the hole and apply 3-in-1 or similar oil. It will take several
applications and a day or two for the oil to soak into the solidified
felt. Be patient. At some point the shaft will free up and turn
If the fan turns fairly freely but still won't work then the bearings
are shot. This displaces the rotor in the stator sufficiently that
the motor won't develop starting torque. You can generally give it a
shove and it'll start. Time to replace the motor. If you have to pay
retail, figure about $80 for the new one. Find your local electric
motor repair shop and buy one from him, as it will be considerably
cheaper than from Duotherm.
From: John De Armond
Subject: Re: A Reminder from Above
Date: Sun, 10 Aug 2008 17:26:05 -0400
On Sun, 10 Aug 2008 10:08:03 -0500, Bob Giddings <firstname.lastname@example.org> wrote:
>Just a reminder from above. It's easy to forget this stuff. If
>you aren't nice to your AC, it won't be nice to you. And if you
>happen to be in Texas, you really, really, really want it to be
I know you just hate to hear from me on things like this but :-)
With the unit off (of course!) reach up in there and see if you can shake the
fan up and down, 90 degrees to the axis of the motor. If so then it's new
motor time. That groan is usually the first sign of a bearing wearing out.
If you can't shake the shaft the schedule an appointment with the roof of your
rig and oil those fan motor bearings! Light machine oil like normally used
literally evaporates in heat like that. My appointment with mine will
probably be this evening.
John, sittin' in 70 deg splendor. 59 last night :-)