Better Air Flow from dash heater/airconditioner

[gary j zingle]

"Another area that I am looking at is to simply use a more powerful blowe=
r
on the dash air system. The problem with the dash air design is too much
air resistance rather than lack of cooling capacity. If we can use a more=

powerful blower and double or triple the air flow it would go a long way
toward making the dash air useful. Anybody know of a source for high powe=
r
blower motors??"

For comparison I got a fan from (junkyard) from a large GM luxury car. It=

looks
almost identical (except for mounting flange) to that used on the GM
motorhome.
With the heater ducting used on these cars I can't run the fan high fan
speed
while wearing a hat. Too much wind.

I agree from my inspection of the existing GM heater box that the problem=

is more
one of duct design/area.

I am making a max air door similar to that used by GM on one of their
recalls.

This modification will allow for lots of air flow at the feet, removing a=
ny
problems
built into the dash distribution system, however it won't do anything abo=
ut
any
problems in the heater box iteself.

Neither the inlet area to the fan or the elbow from the fan to the heater=

box seem
very generous. They both are about 25 square inches, considerably smaller=

than the opening to the ducting in the dash.

How much of the problem is inlet air restriction? Has anyone come up with=
a
solution for this restriction or do we go to a 900 hp heater fan to force=

the
air through?

Regards


Gary Zingle
1973 GMC 26 foot

 

[gene]

don't let him fool you, he now has 23 new May projects.
gene

>In a message dated 4/28/00 11:30:18 AM Pacific Daylight Time,

>
> some clothes drier hose (3"), cut a hole in the duct over at the far left,
> and install a 3" collar. Then go over to the blower box and cut a 3" hole
in
> that and put in a collar. In may have been in to top of the blower, I would
> have to be looking at it to recall correctly. Hook up the hose between
these
> two and you have now relieved the air restriction. I posted this before but
> don't recall the comments. This old guy (older than me) used to work on
>GMC's
> and seemed to know them up down and sideways. Any comments? I have not done
> this yet. Some of you that might be more familiar with the geometry of this
> system might want to enlighten those of us that are not so fortunate.
> >>
>
>Larry, at Ukiah I met Bud Bronson from San Diego, he has something like
that.
>He also has the openings covered and operated by vacuum solenoids. He can
>open and close them at will from inside. I took some pics and so did Gene
>Fisher. Bud also promissed to help me with the modification. He also
>recommends removing the evaporator and cover the top. I have a kit from
>Clasco for improving the a/c on the early coaches so i'll be doing that at
>the same time. This is my May project.
>
>Manny Trovao
>73 Custom/ex-Glacier
>San Jose, California
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/