> Has anyone successfully modified a Type 2 Vehicle A/C unit to
> recirculate air rather than use 100% outside air at all times?
>
Waldo,
Last weekend I followed Ray Zand's directions (compliments of Billy
Massey's post at
http://www.web-access.net/~bmassey/air_conditing.html )
and modified my Type II system to recirculate the inside cabin air . I
accomplished this by using a 4 in hole saw to carefully cut the hole in
the back of the blower box which opened up a passageway next to the
firewall opposite and behind the Type II max air outlet ducts inside the
cab. I drilled pilot holes from the the outside through the newly expose
passageway and carefully cut a 2 3/8 by 5 inch hole in the firewall.
This hole or slot connected the previously hidden passageway to air
inside the cab. This air now feeds directly into the blower squirrel
cage. I fashioned an aluminum plate to cover the original outside air
inlet, but left two 1 1/2 inch holes in the plate at the top which I
covered with hardware cloth to keep the mice out. I also fashioned from
aluminum angle the diverter bar and installed it as shown in Ray's
instruction. I did not need to install the stiffener bar in the bottom
of the box since mine was already equipped with a piece of flat bar in
the area Ray's instructions said one was needed.
Was it successful? Well, I didn't have too many skinned knuckles and I
definitely can tell that the inside cabin air is now being pulled in to
the return air duct. I have noticed that the AC compressor now does not
cycle off as frequently as before. I am speculating at this point that
there is now less ice building up on the evaporator coil which lessens the
need for the compressor to be cut off by the freeze protection switch.
This I believe would be because the cabin air now becomes less and less
humid as it recirculates in the AC system ,as compared to the humid air
that was continuously being drawn in by original Type II arrangement and
was freezing on the evaporator.. Therefore the cab area feels cooler,
but that may be because the AC is now better able to dehumidify the space.
I haven't had time yet to do much road testing of the new (for me)
system, so I can't conclusively say if the modifications will prove to be
a big improvement. And it could be a while before I am able to road test
it properly. This is because tonight while trying to run the fan clutch
diagnostic test outlined in the shop manual, an O-ring blew out on the
high pressure cut off switch. All I could do was cut off the engine and
watch that precious R12 escape to deplete more of the Ozone Layer. The
hoses and fittings are all less than 2 years old so I don't know why the
blow out occurred.. I hope the fan clutch diagnostic test was not the
cause of the blow out. I suspect it was just coincidental.
Well, as Arch would say, that's what I did.
Phil Stewart
'76 Transmode, TN
wner-gmcmotorhome]On Behalf Of Waldo Love
