| [GMCnet] Roof AC Rattles on startup [message #144463] |
Sun, 25 September 2011 08:31  |
Erv Troyer
Messages: 125
Registered: February 2004
Location: Lagrange, IN
Karma:
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Senior Member |
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On Sat, 24 September 2011 18:08 D C "Mac" Macdonald wrote: <in part>
>>>>>>>>>>>>>>>>
Figured I'd turn on the on-board air system just for grins. Great
clattering and rattling occurs,
but what the heck! Maybe it will just die and be done with it.
<<<<<<<<<<<<<<<<<<
Mac, about that "clattering and rattling" -
This is for all of you with the original Duo-Therm roof air conditioner
(and there are quite a few, judging from the coaches at Goshen at GMCMI). You
can tell if you have an original Duo-Therm AC if you have a third control
knob that controls the air flow to the front or the rear of the coach.
These units use a piston type compressor which vibrates somewhat on the
first startup, but they are mounted on rubber grommets so the noise in the
coach should not be very loud, and should quiet down to a gentle "purr"
within a few seconds. However, if you hear a very loud metal-to-metal hammering
when the compressor first starts, then you probably have a mis-installed
mounting bolt.
The compressor is mounted directly above the mounting bolt hole located at
the passenger side rear of the unit. We (Duo-Therm) provided a special
mounting bolt that had a 1/2 inch thread at one end and several inches of
thread at the other end. The installer was supposed to install the short end
into the air conditioner, and if the bolt was too long for the roof thickness
they were supposed to cut off the long threaded end to fit. However, I
have seen many of these where the installer was too lazy to cut off the bolt
so they put the long threaded end up, put a nut on the short thread, and
cranked up the bolt. This forces the bolt against the bottom of the compressor
- and you get a severe noise when the compressor starts.
To check this bolt you have to remove the complete air box from the
ceiling. If you find this bolt with the short thread at the bottom, then you will
have this problem. Remove the bolt, cut it to the right length, then
re-install it with the short thread turned up.
I would have thought that after 30 years these problems would have been
corrected, but I guess there were some owners that just thought that was how
they were supposed to work - I found a 1977 Birchhaven in 2010 that STILL
had this problem. This was a Coachmen built unit, and it reflects the
typical poor workmanship that I have seen so many times in northern Indiana built
RV's in the 70's and 80's. I am not trying to get an argument started with
that statement - but I calls 'em as I sees 'em.
Erv Troyer
Lagrange, IN
(26 years with Duo-Therm)
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Erv Troyer Lagrange, IN
74 Sequoia
reo43@aol.com
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