"I'm trying to remove the evaporator and the heater core. I'm doing it
because =
of low air flow at the outlets. I thought maybe the evaporator was plugge=
d
up =
and if I could get it out I could clean it. It looks like you could swing=
it =
out a little and clean it if the hoses are flexible enough. I'm having a =
little trouble getting the screws out that hold it in. I also thought I'd=
=
take the heater core out and have it checked while I'm in there. Seems I'=
m =
having trouble getting the screws out of it's brackets!"
Although I can't remember the specifics of those fasteners I found it to =
be
easy once the heater box was on the bench.
If you go there you may find that getting the heater box out isn't easy.
Comes
out through the grill opening after removing 5 - 3/8" bolts that hold the=
box
to the firewall.
2 bolts on the passengers side. One at the top and one at the bottom.
The top one is accessed from behind the glove box. The bottom one
from below the dash.
3 bolts on the drivers side. Worst one (as I recall) was the one closest=
to the master cylinder.
"..........Like yours mine had the symptoms of very little air flow. My
first
discovery was that the blower motor turned backwards. That one had me
scratching my head for a while because I didn't believe what I thought I
was seeing. A new blower improved things a little but not much.
I think some of the later models had better air flow but mine is a '75 PB=
and there is very little air flow even when working properly. The AC is
poorly designed like many other things on these old beasts. I don't know
the details of the later models and I think someone sells kits to upgrade=
things also but if you've already got everything apart it's fairly easy t=
o
improve the air flow. I'm making the assumption that yours is like mine
otherwise you wouldn't being trying to improve it............"
I completed the recirc air modifications and put the heater box back in
and found air flow through the new recirc air opening to be as I expected=
(since the fan motor on mine is the same as that used on large Cadilacs
and blows lots of air.)
I decided the problem must be in the dash duct work.
Tore the dash apart (what the heck the windshields needed replacing
anyhow) and discovered (just as I had been warned by those that had
gone before me) that GM did not pay any attention to sealing the ducts
when they assembled them.
It was obvious that the fan was blowing lots of air but it was being used=
to
condition the space under the dash.
Rebuilt the dash and put it back in last night. Now I get air out the duc=
ts
much more as I had hoped (given the volumne of air put out by the fan.)
I wouldn't recommend dash removal if you are planning on going
anywhere soon though.
The dash on mine was out for most of June and the old windshields
went back in temporarily last night so that the GM could go to a family
reunion this weekend.
Back apart again next week. Not finished yet.
As many of you know, just one of those things.........once the windshield=
s
and dash are out it is easy to remove the side panels..................th=
en
it is
easy to replace the plywood floor..............remember those new speaker=
s
.....................CD changer................
All just part of the game, but at least I am still having fun.........sur=
e
would
like to go camping though............
Regards
Gary Zingle
1973 GMC 26 foot
because =
of low air flow at the outlets. I thought maybe the evaporator was plugge=
d
up =
and if I could get it out I could clean it. It looks like you could swing=
it =
out a little and clean it if the hoses are flexible enough. I'm having a =
little trouble getting the screws out that hold it in. I also thought I'd=
=
take the heater core out and have it checked while I'm in there. Seems I'=
m =
having trouble getting the screws out of it's brackets!"
Although I can't remember the specifics of those fasteners I found it to =
be
easy once the heater box was on the bench.
If you go there you may find that getting the heater box out isn't easy.
Comes
out through the grill opening after removing 5 - 3/8" bolts that hold the=
box
to the firewall.
2 bolts on the passengers side. One at the top and one at the bottom.
The top one is accessed from behind the glove box. The bottom one
from below the dash.
3 bolts on the drivers side. Worst one (as I recall) was the one closest=
to the master cylinder.
"..........Like yours mine had the symptoms of very little air flow. My
first
discovery was that the blower motor turned backwards. That one had me
scratching my head for a while because I didn't believe what I thought I
was seeing. A new blower improved things a little but not much.
I think some of the later models had better air flow but mine is a '75 PB=
and there is very little air flow even when working properly. The AC is
poorly designed like many other things on these old beasts. I don't know
the details of the later models and I think someone sells kits to upgrade=
things also but if you've already got everything apart it's fairly easy t=
o
improve the air flow. I'm making the assumption that yours is like mine
otherwise you wouldn't being trying to improve it............"
I completed the recirc air modifications and put the heater box back in
and found air flow through the new recirc air opening to be as I expected=
(since the fan motor on mine is the same as that used on large Cadilacs
and blows lots of air.)
I decided the problem must be in the dash duct work.
Tore the dash apart (what the heck the windshields needed replacing
anyhow) and discovered (just as I had been warned by those that had
gone before me) that GM did not pay any attention to sealing the ducts
when they assembled them.
It was obvious that the fan was blowing lots of air but it was being used=
to
condition the space under the dash.
Rebuilt the dash and put it back in last night. Now I get air out the duc=
ts
much more as I had hoped (given the volumne of air put out by the fan.)
I wouldn't recommend dash removal if you are planning on going
anywhere soon though.
The dash on mine was out for most of June and the old windshields
went back in temporarily last night so that the GM could go to a family
reunion this weekend.
Back apart again next week. Not finished yet.
As many of you know, just one of those things.........once the windshield=
s
and dash are out it is easy to remove the side panels..................th=
en
it is
easy to replace the plywood floor..............remember those new speaker=
s
.....................CD changer................
All just part of the game, but at least I am still having fun.........sur=
e
would
like to go camping though............
Regards
Gary Zingle
1973 GMC 26 foot
