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retro 65 chevy impala???

wagonmaster on Thu May 20, 2004 12:41 AM User is offlineView users profile

Year: 1965
Make: chevrolet
Model: Impala Wagon
Engine Size: 500 ci
Refrigerant Type: 134
Country of Origin: United States

Just spent the whole evening reading posts here. Looking for some input. 65 Chevy Impala Wagon with
a 500 ci Cadillac engine,factory air with STV system, compressor and condenser not presently installed.
Want to refit with 134,Sanden/Seltec compressor (will fab mounts) , parallel flow condenser (will fab also)
and do away with STV system. Plan to install valve in heater hose as heater core now has constant flow
(that can't help) Is it possible to upgrade blower motor/squirrel cage? This wagon is huge by large with
LOTS of glass and I'm in Florida where although ambient rarely gets to 100 degrees the humidity often
does. Will be upgrading engine cooling system at the same time as although it gets the job done now
I'm sure it won't with AC (which is probably why previous owner pulled the condenser and installed
two pusher fans in front of radiator) Open for suggestions as its coming of the road this friday...

The World Today... Never enough time to do it right, Always enough time to do it twice...

wagonmaster on Thu May 20, 2004 1:07 AM User is offlineView users profile

Oh well, newbie here meant to post in conversion and retrofitting

The World Today... Never enough time to do it right, Always enough time to do it twice...

Chick on Thu May 20, 2004 7:26 AM User is offlineView users profile

You already have a decent plan.. The parallel condenser and use the SELTIC Compressor It has the same mounting as the sanden, but is quieter and in my opinion better than the Sanden. The fact that the previous owner had to install pusher fans would make me want to check out the cooling system before adding the AC..Might have a clogged radiator, or weak water pump etc.. Fan shroud is important also You have to pull a lot of air thru the radiator/condenser. So even after checking the cooling system, I would leave the fans on..You can also change to a CCOT system if you want to do away with the STV..E-mail the guys at for suggestions in that area. But, it is the busy season, so be patient with them..... As far as the blower motor, a car that old may have leaks around the divertor doors making it feel weak,or the evaporaotr may be partially clogged with dirt and leaves. A good idea to check both..Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

bohica2xo on Thu May 20, 2004 3:12 PM User is offline


I actually owned a '65 Impala for several years, while living in AZ. It did have enough cooling capacity, if you maintained the system well. The caddy swap is an interesting one. My car was a 327/300hp powerglide setup, but the a/c system was the same as yours.

I would NOT remove the STV. The TXV / STV system was expensive to build, and the only reason they used it was for better performance. Back then A/C was a premium option, and they made sure it was worth what they charged for it. Tightly controlled evaporator pressures are important to maximize cooling.

Shutting down the water flow through the heater core is not worth much on the Impala. If you do this, make sure you use 2 valves, and keep the loop flowing when you shut down the heater core. I have tried it, obviously.

Parallel flow condensor. This is a BIG yes! One of the things that has improved a LOT in the past 30 years is condensor design. The more subcooling you can offer that system, the better it will perform. Use the biggest parallel flow that you can fit in the car. It should see the air first. Place transmission coolers and oil coolers between the condensor and the radiator.

Fans. At idle, the fan(s) are important. The fan clutch is the biggest culprit in low speed cooling. I tried several fan alternatives, but found that a good clutch and OEM fan worked out the best. In this case, I would use the caddy fan, clutch, and shroud if at all possible. The pusher fans can't hurt, if there is room for them. I would look at a time or temperature switch to run the fans a few minutes after you shut the engine down. This will extend the life of your underhood components a lot.

Compressors. The A6 would be my first choice. Bt far the best compressor for longevity, and compatibility. The OEM mounts are strong, and vibration free. For good idle performance, my '65 spun the crap out of the compressor - about a 2.5:1 overdrive as I recall. Even though the engine spent a lot of time above 3500rpm, the A6 never complained.

My second choice would be a Seltec. There is only one with enough volume to match the A6 output - the 21 series. Look at this thread:
500 cid caddy compressors
Where we discussed it in some detail. Apparently there is an R4 mount out there for the 500..... bad plan.

The information for adjusting the STV for 134a is here on this site. It is not difficult, and well worth the effort. The blower in that car was always adequate, just make sure it is in good shape, and all of the connections will pass 30 amps without too much resistance. The speed controll resistor is located in the engine compartment, and subject to corrosion on all of the connections. I would look at installing a relay for high blower that bypasses the resistor and feeds battery power to the blower - rather than feed the blower through several connections, 20 feet of wire and a dash switch (all of them 39 yrs old and corroded somewhat).

My '65 cooled very well. With 4 people in the car, in June. I could leave Bullhead city, AZ at 2:00 pm, and the girls in the back seat would have their sweaters on before I got halfway to Kingman AZ. Try that in a new car. My 2003 Explorer won't get that cold - ever! I can drive from Las Vegas NV to Kingman AZ, and the back seat will still melt a chocolate bar. The explorer has an orifice tube - a 68 cent part. Keep the TXV/STV system if you want cooling POWER.

"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

wagonmaster on Thu May 20, 2004 9:14 PM User is offlineView users profile

WOW! What a kick @$$ forum, this is just too "cool"... And exactly what I was looking for.
After reflecting on your replies I've decided that maybe I'm biting off more than I can chew.
I already have a frame off 63 belair wagon and a son racing jr. dragsters so I've decided to
break this project up. First phase will concentrate on maximizing engine cooling system.
The radiator that Cadillac installed with their 500 ci heat pumps(engine) was a very wide
four row crossflow unit that just won't physically fit in the Impala. The current three row
vertical flow in the car is in great shape just undersized IMO. So my first move will be to
open the radiator opening in the core support approx. 2 inches on each side and make
room for a 29 in. wide aluminum crossflow radiator. This coupled with a better shroud had
better cool this engine without the two pusher fans. Understand this is a very low rpm
torque monster, 2000 rpm @ 80 mph in overdrive. A higher flow water pump is available
but if needed I'll try to overdrive it more with junkyard pulleys first.

Next phase will be to address the firewall equipment, clean and flush evaporator check
diverters and actuators,replace flex ducts from plenum to outlets (I know their leaking).

Finally, mount compressor,receiver/dryer, condenser (probably shroud it to force engine
fan to pull through it at low/no speed. Plumb it, wire it ( I hear what your saying about
voltage drops on 40 year old harnesses, I've been down that road before.) charge it and
freeze. Geez its sounding more like a project all the time.

I hear what your saying about the A6 no doubt, I just don't like the stock Cadillac mount
location, makes it tough to get to carb idle screws and have to run an offset air cleaner base,
this is probably a personal problem...

OK now for a couple of new questions: evaporator core, to pressure check this how much
air pressure should I use?

Bench test: I saw a Mitch post on bench testing a POA . Is there anything similar I could do
with the TXV/STV? Any issues with oil compatibility with TXV/STV system? Are they available new?

Chick and bohica2xo: Thanks so much for taking the time to lend some guidance. I'm grateful,
and bohica2xo I hope mine works half as good in my swamp as yours did in the desert. I don't
really want the girls putting sweaters on, I just want them to quit complaining about getting their
hair messed up at 80 mph with all 5 windows down...

The World Today... Never enough time to do it right, Always enough time to do it twice...

bohica2xo on Thu May 20, 2004 11:17 PM User is offline


Glad to help. The car sounds like a nice project, and you sound like a busy man. I will try to address your latest stuff in order. here is a link to a comparison of systems:

CCOT vs. TXV's

I would look at having a nice 4 row vertical flow radiator made up for that car. Cuttting the radiator support will weaken it, because it removes the stiffening flanges formed into it. Adding a full 30% to the radiator with a 4 row core is probably enough - it was for my 454 in the Nova (another story!)

I doubt that you are running out of waterpump just yet - unless the 500 is heavily modified. Use the stock drive ratio, unless you find an overdrive in your junkyard search that is a simple swap. My dad was involved with the Pikes Peak Toronado's, and they ran out of waterpump around 550 hp @ 6000. They were a bear to cool once the heads got too hot.

Thermostat. I know you have not mentioned it, but experience has taught me to drill a 3/32 diameter bleed hole in the plate. This allows the system to bleed easily, but more important causes better modulation. with a little bit of flow PAST the capsule, it opens more gradually, and just a bit sooner. This reduces the heat shock to the rest of the system.

Firewall equipment. A very through job you plan on! a lot of work, but worth it. By now the foam in there has turned to dust. Make sure the blend door seals well, and you can leave the heater core working - nice to have for de-humidification when the swamp cools down some.

Compressors. I believe the caddy mount you are describing is a fixed mount on the engine centerline. I understand why you are not thrilled, with the tight carb clearance. If the Seltec 21 is shorter, you could mount it in the same location, if you want to fabricate mounts. Or you could relocate the A6, but again a lot of work. As long as you have enough pump capacity, whatever you choose to do......

Wiring. The only speed that needs a relay is "high". Since a resistor current limits all of the other speeds, it makes no difference if the total resistance is spread around the system. But on high, you want the full 14volts at the brushes...

Pressure checking the evaporator:
60 psi and a bucket of water should do just fine. On a hot day, the static on the system will go over 125psi, but I have never found an evap that leaked only at high pressures.

Bench testing the pressure controls:

Testing a TXV has been covered here someplace. Testing and calibrating the STV is the same as a POA - just different terms to describe the same type of animal... Test everything you can on the bench, it reduces the demons you chase after assembly.

Sweaters.... I was a much younger and single man when I owned that car. It was famous among my peers as a "nipple inspection device"..... I drove it all over, and it cooled well in the swamps too - always a puddle under the right side at idle.

Good luck with your project.

"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

wagonmaster on Sat July 19, 2008 10:40 AM User is offlineView users profile

Bringing this back up from the ages... Where does the time go? As projects go this one got further
and further apart and then sidelined for a while. Going back together now tho with great advice
on the AC from here. My only sticking point at the moment is a compressor choice. Originally I was
going to go with the Seltec 21 HXD but it seems that they're not as available now as they were
4 yrs ago. I've been looking around the forum in search of something with near the displacement
of the A6 that is out of the question do to space restraints. Particularly interested in the V7/V5
series. My understanding from other posts is that the V5/V7 clutch will interchange allowing me
to have the V belt drive. I am leaning toward keeping the STV/TXV so my question is since I haven't
explored whats going to happen with the STV and variable disp. of the V7 possibly working against
each other I'm wondering if I could just fix the disp. of the V7 in "high stroke" and run the system
that way.

Any thoughts/ideas will be much appreciated. Thanks again.

The World Today... Never enough time to do it right, Always enough time to do it twice...

Edited: Sat July 19, 2008 at 10:58 AM by wagonmaster

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