AC Improvements Again

[dick kennedy]

I went junkin yesterday and found three old ARA aftermarket AC units. They
were all early 80's vintage, Fords no less; and I didn't run across any OEM
installations. One of the units has a bad evaporator and the other a bad
fan so I think I've got two complete working units. Cool city here we come.

These units are both heat and cool and much too big to fit under the
passenger seat so I'm thinking under the couch just behind the driver. I'm
still at the collecting pieces stage so am just schemeing and planning so
far. I haven't gotten any firm info on the units that fit under the
passenger seat so would still like to hear from someone who knows the
details on these.

I'm trying to figure out how to 'T' into the dash AC lines without cutting
the original hoses. The pressure side is about 5/16" and the suction side
is about 1/2". They're O ring fittings and not standard compression
fittings. I think they're an SAE standard but I don't know any details. I
need someone to tell me what these fittings are called, what size they are
and where to find the T's. Actually I've got the high side T fitting from
the Ford that will work but for the low side they just cut the original
hose and installed a T with hose clamps. If I cut the hose and do that I
won't be able to go back to original if I need to besides I just paid big
bucks for that hose last year and want to use a threaded fitting. The ARA
uses 1/2" suction line so I need an inline threaded O ring t with a 1/2"
hose barb off the side. Also the hoses off the ford are in good shape and
are usable but should I spend the money to get the newer lower leakage
stuff for R-134 compatibility?

My buddy who does AC doesn't do car stuff so I'm in learning mode here.
I've finally figured out how to get enough cooling capacity but I'm still
wondering if I'm going to have enough condenser for this. I know it's
marginal but I don't know which side of the margin it is on. Then as
someone pointed out there's the extra load on engine cooling. Does anyone
have any experience with helper fans? Do they help or do they just block
some of the flow?

Enjoy

Dick

 

[dave1]

>I'm trying to figure out how to 'T' into the dash AC lines without cutting
>the original hoses. ....

Dick,

If you find the information you are looking for, please be sure to post it
to the list. I am thinking about doing the same thing. I will be very
interested in hearing how your installation works out.

Dave
73 Sequoia

 

[mark grady]

Dick --

FWIW --
The standard, original GM hoses will leak refrigerant. They weren't that
good even when new, particularly the big suction line. Put in some UV tracer
dye and they'll look like glowing worms under the UV light after you shut
down.

If you've got enough R-12 to last you for a while, then maybe you can live
with a slow leak. You'll have to call it.

I do understand the cost of hose replacement though, and especially if
you've just put on one new hose. If the new one's barrier style, then I'd
consider replace what's left depending on the pain in your wallet area.

You're almost in a pay now or pay later situation, freon each year or hoses.
Personally, I know my hoses seep a little, and I just put in a half pound or
so every year. Someday, I'll have to do a makeover and clean up my
pollution.

Get your hands on a NAPA "TEMP" catalog. You can find all the fittings you
should need, and yes, they are O-ring style. They used to have quite a
selection, but I haven't looked in awhile. You used to be able to get O-ring
to hose barb fittings, but I'm not sure if they're still available since the
world has went to barrier style hoses.

You can also get fittings (and probably T's) from ARA, since they do a lot
of second evap stuff. Worth a shot.

The only fitting on the original GMC suction side is right at the evap, and
I don't know if you'll find a T fitting other than the kind ARA used (that
is, hose barbed).

I'm just thinking out loud here, but you could also take your fittings to
someone who welds aluminum and 'make' the fitting you need. That's just
another thought, especially if you've got a lot of junk yard parts and
fittings. That would be pretty easy to do if a fella' was handy with the
aluminum welder.

If you've got the original GM condenser, you've got a lot of capacity, if
(and only if) you get some air moving.

Consider the Hayden 2797 severe duty fan clutch that Duane Simmons talks
about, but some people report that can be noisier than the 2747 (I guess
we'd call that heavy duty?)

Standard is the 2705. Jim Bounds says that's the ticket, but with two
evaps... You've got to get it engaged at low speeds to move some air.

I can get you one and ship it to you from FW pep boys if you can't find it
in Kokomo. I'm going to get one for myself this week sometime. Mine no
longer reassures me that its working with that roar I like to hear.

I'd question helper fans only since the original fan moves so dang much air
(when it works) anything else would seem to just be in the way.

If your radiator is in decent shape and you've got a 50-50% mix, you
shouldn't have any problem with overheating. I'm growing increasingly
convinced that the heat exchange quality of the radiator, the coolant mix
and state of engine tune has more to with overheating than anything else.

One final thought; without a solenoid valve to turn off the supply of
refrigerant to the second evap, it will freeze up when it's fan isn't
running. The GM cycling clutch will keep the front dash evap from freezing,
but with no air moving through your second evap, it will freeze.

Not a big deal, but be sure to plan for good drains for the condensate that
will result from this evap.

I will say this... With the changes you've made to your from evap and this
second one under the couch, you'll have a meat locker on wheels.

Mark

| Original message on behalf Of Dick Kennedy
| Sent: Sunday, June 20, 1999 10:25 PM
| To: gmcmotorhome
| Subject: GMC: AC Improvements Again
|
|
| I went junkin yesterday and found three old ARA aftermarket AC units. They
| were all early 80's vintage, Fords no less; and I didn't run
| across any OEM
| installations. One of the units has a bad evaporator and the other a bad
| fan so I think I've got two complete working units. Cool city
| here we come.
|
| These units are both heat and cool and much too big to fit under the
| passenger seat so I'm thinking under the couch just behind the driver. I'm
| still at the collecting pieces stage so am just schemeing and planning so
| far. I haven't gotten any firm info on the units that fit under the
| passenger seat so would still like to hear from someone who knows the
| details on these.
|
| I'm trying to figure out how to 'T' into the dash AC lines without cutting
| the original hoses. The pressure side is about 5/16" and the suction side
| is about 1/2". They're O ring fittings and not standard compression
| fittings. I think they're an SAE standard but I don't know any details. I
| need someone to tell me what these fittings are called, what size they are
| and where to find the T's. Actually I've got the high side T fitting from
| the Ford that will work but for the low side they just cut the original
| hose and installed a T with hose clamps. If I cut the hose and do that I
| won't be able to go back to original if I need to besides I just paid big
| bucks for that hose last year and want to use a threaded fitting. The ARA
| uses 1/2" suction line so I need an inline threaded O ring t with a 1/2"
| hose barb off the side. Also the hoses off the ford are in good shape and
| are usable but should I spend the money to get the newer lower leakage
| stuff for R-134 compatibility?
|
| My buddy who does AC doesn't do car stuff so I'm in learning mode here.
| I've finally figured out how to get enough cooling capacity but I'm still
| wondering if I'm going to have enough condenser for this. I know it's
| marginal but I don't know which side of the margin it is on. Then as
| someone pointed out there's the extra load on engine cooling. Does anyone
| have any experience with helper fans? Do they help or do they just block
| some of the flow?
|
| Enjoy
|
| Dick
|
|

 

[dick kennedy]

Mark,

I installed main hoses on AC last year. Got them from Golby. I've got the
hoses from the ford but my AC guy recomended buying new hose. I need 17
feet if I allow a little slack. The short hoses were expensive so I hope
I'm not getting in too deep on those long hoses. If they're $10 per foot I
may re evaluate and try the system without the extra unit.

I've asked the NAPA guys twice about fittings and drew a blank. The new PEP
Boys and Autozone are eating them alive but they keep screwing up. It took
me a week to get the right expansion valve from them. I'll specifically ask
them about the TEMP catalog.

I talked to SCS Frigette about a week ago and they weren't interested in
selling anything. I then talked to ACME today and they knew what I needed
and were helpful. They're in the AC business. Their fitting is a crimp type
so it would be best to order the hose with it. I didn't know the length
needed and forgot to ask price. If somebody wants to do it the easy way
they have all the stuff and I'm sure they could put together a kit with
everything needed.

The '79 Tioga that I had had ARA AC in it. I think they're out of business
now.
Yes that's the Tioga that just sat in the driveway and ran when I wanted it
to. No breakdowns and no major surgery needed. That really was the good old
days. But, I digress. Last year with both roof AC's running I could only
hold 98 degrees going across Iowa.

The second evap has a thermostatic expansion valve so it should prevent
freezing. On second thought both evaps have same pressure so should be
same temp. Second guy can pool coolant but not get cooler unless first guy
gets starved. The highest temp sets temp of whole system.

I don't know what fan I have but it works ok at highway speeds. At constant
speed on a hot day it will go on and off just like it should. I think if
it were more agressive I would have fan all the time. It's ridiculous to
need fan when ram air is available. I've always thought that fan isn't
needed at speed but GMC doesn't seem to work that way.

Low speed is a different story. Starting cold and at idle I didn't seem to
have enough fan for the condenser and the AC would stop working after a few
minutes. Garden hose on condenser would bring it back to life. Something
about the system wasn't right but I never really figured it out. That
prompted this year's rebuild and replacement of accumulator and expansion
valve.

The little that I had it working last year there were several times when it
coughed hard while in town and stopped in traffic. It was like the carb got
a bubble of vapor and choked on it then passed it and ran ok again. That's
a wierd form vapor lock but that's how it seemed to act. If this proves to
be the case I'll need to get more air moving somehow. One step at a time.

Enjoy

Dick

>Dick --
>
>FWIW --
>The standard, original GM hoses will leak refrigerant. They weren't that
>good even when new, particularly the big suction line. Put in some UV tracer
>dye and they'll look like glowing worms under the UV light after you shut
>down.
>
>If you've got enough R-12 to last you for a while, then maybe you can live
>with a slow leak. You'll have to call it.
>
>I do understand the cost of hose replacement though, and especially if
>you've just put on one new hose. If the new one's barrier style, then I'd
>consider replace what's left depending on the pain in your wallet area.
>
>You're almost in a pay now or pay later situation, freon each year or hoses.
>Personally, I know my hoses seep a little, and I just put in a half pound or
>so every year. Someday, I'll have to do a makeover and clean up my
>pollution.
>
>Get your hands on a NAPA "TEMP" catalog. You can find all the fittings you
>should need, and yes, they are O-ring style. They used to have quite a
>selection, but I haven't looked in awhile. You used to be able to get O-ring
>to hose barb fittings, but I'm not sure if they're still available since the
>world has went to barrier style hoses.
>
>You can also get fittings (and probably T's) from ARA, since they do a lot
>of second evap stuff. Worth a shot.
>
>The only fitting on the original GMC suction side is right at the evap, and
>I don't know if you'll find a T fitting other than the kind ARA used (that
>is, hose barbed).
>
>I'm just thinking out loud here, but you could also take your fittings to
>someone who welds aluminum and 'make' the fitting you need. That's just
>another thought, especially if you've got a lot of junk yard parts and
>fittings. That would be pretty easy to do if a fella' was handy with the
>aluminum welder.
>
>If you've got the original GM condenser, you've got a lot of capacity, if
>(and only if) you get some air moving.
>
>Consider the Hayden 2797 severe duty fan clutch that Duane Simmons talks
>about, but some people report that can be noisier than the 2747 (I guess
>we'd call that heavy duty?)
>
>Standard is the 2705. Jim Bounds says that's the ticket, but with two
>evaps... You've got to get it engaged at low speeds to move some air.
>
>I can get you one and ship it to you from FW pep boys if you can't find it
>in Kokomo. I'm going to get one for myself this week sometime. Mine no
>longer reassures me that its working with that roar I like to hear.
>
>I'd question helper fans only since the original fan moves so dang much air
>(when it works) anything else would seem to just be in the way.
>
>If your radiator is in decent shape and you've got a 50-50% mix, you
>shouldn't have any problem with overheating. I'm growing increasingly
>convinced that the heat exchange quality of the radiator, the coolant mix
>and state of engine tune has more to with overheating than anything else.
>
>One final thought; without a solenoid valve to turn off the supply of
>refrigerant to the second evap, it will freeze up when it's fan isn't
>running. The GM cycling clutch will keep the front dash evap from freezing,
>but with no air moving through your second evap, it will freeze.
>
>Not a big deal, but be sure to plan for good drains for the condensate that
>will result from this evap.
>
>I will say this... With the changes you've made to your from evap and this
>second one under the couch, you'll have a meat locker on wheels.
>
>Mark
>
>
>| Original message on behalf Of Dick Kennedy
>| Sent: Sunday, June 20, 1999 10:25 PM

 

[mark grady]

- - Chain saw'd -

| The second evap has a thermostatic expansion valve so it should prevent
| freezing. On second thought both evaps have same pressure so should be
| same temp. Second guy can pool coolant but not get cooler unless first guy
| gets starved. The highest temp sets temp of whole system.

Unless you re-wire, the dash (front) pressure switches (low/high) and the
cycling clutch therm will control the compressor.

The second evap will match, but if the fan in it is off, it will tend to
freeze. Its expansion valve will prevent flooding, but it can't stop the
refrigerant flow completely.

This is a really small point in the overall scheme of things, you can leave
the fan on low and probably be OK.

| Low speed is a different story. Starting cold and at idle I
| didn't seem to
| have enough fan for the condenser and the AC would stop working
| after a few
| minutes. Garden hose on condenser would bring it back to life. Something
| about the system wasn't right but I never really figured it out. That
| prompted this year's rebuild and replacement of accumulator and expansion
| valve.

I think (but I don't know for sure) that different models of fan clutches
have different 'disengaged' characteristics. The secret is to find one that
has maybe 10-15% disengaged, 75% engaged. This will move enough air to let
the condenser do its job.

I have no idea how you find one with these characteristics other than trial
and error, but maybe someone will let us all know. I'd love to find one for
my self, as we frequently set at idle in cooler weather but still need good
A/C due to heat gain from the sun through those big picture windows.

| The little that I had it working last year there were several
| times when it
| coughed hard while in town and stopped in traffic. It was like
| the carb got
| a bubble of vapor and choked on it then passed it and ran ok again. That's
| a wierd form vapor lock but that's how it seemed to act. If this proves to
| be the case I'll need to get more air moving somehow. One step at a time.

Fortunately, this is one problem I haven't had. I must be lucky, (if there
is such a thing). Many of the GMC'ers talk about vapor lock, etc. Again, I
think you're on the right track, you've got to keep air moving to get rid of
the heat.

I've changed a lot of fan clutches over the years to solve this problem, and
it was before I knew about the different models. I've also used a dremel
tool to make new 'slots' to change the engage temperature, and I used to
have a written procedure someone sent me to accomplish that. It isn't too
hard to figure out which way to make the new slot, take a hair dryer and
change the 'pre-load' on the thermostat coil.

I'll pose this open question:

Does anyone know if Hayden publishes the characteristics of its various fan
clutch models?

Mark