CLASSIC CAR AIR CONDITIONING OF THE 1950's!
This guide is a work-in-progress and I will add to it as time permits. If you have interest please check back occasionally!
Information about A/C setup, repair, retrofitting etc. is all over the web. My goal here is to only bring out some useful information I haven't seen elsewhere.
In 1955, Ford introduced its first A/C system, Select-Aire. Select-Aire integrates the heater core and evaporator coil in the same unit, not underdash but within the dash. Until 1958, cold air was directed thru vents ABOVE the dash. From 1958 on, cold air was directed thru a chrome-plated metal vent register below the dash.
A more economical dealer-installed A/C system named Polar-Aire made its appearance in 1957. Polar-Aire was a stand-alone hang-on unit that made no changes to the stock heater setup. In fact design-wise it was very much in keeping with standard aftermarket A/C units, except that it had the official Ford insignia.
New Ford buyers could choose between Select-Aire and Polar-Aire for quite a number of years. There's no denying the Select-Aire unit is more desirable and better looking then Polar-Aire from a visual standpoint. The '59 Select-Aire all-chrome blower outlet box (with the little chrome joysticks) is really an eye-popper! However, it must be mentioned that the Polar-Aire units, as well as any aftermarket A/C units, vastly out-perform Select-Aire. That is, if A/C quality is measured by comfort on a hot day.
Select-Aire used only a single squirrel-cage fan, as you find in a stock heater system. A single squirrel-cage is fine for a heater, but woefully inadequate for projecting cold air especially into the back seat area. Also, Select-Aire had only TWO vent registers you could point and aim. So even if it had a more powerful fan, it would still go only two directions. That might be OK for Vermont in April, but doesn't cut it for Phoenix in July.
Polar-Aire had a dedicated fan just for the evaporator coil. It was a propeller fan about 6 inches diameter, and later models went to a double-squirrel-cage fan which is even better. Polar-Aire had three large vent outlets, plus two smaller outlets on the side, which was much better for diffusing cold air thruout the car.
Under the hood, Ford factory air was simple by today's standards, but still not as simple as it should have been. I have seen (and installed) several different varieties of aftermarket brackets on these engines, and I would recommend ANY aftermarket version over the factory setup. More details to follow.
Factory brackets -- In 1955, compressor was vertically mounted, low on the passenger's side. Beginning 1958, the compressor moved to its present familiar position, high on the driver's side. Factory brackets are in several pieces, and for '59 at least they depend on the power steering bracket even if you don't have power steering. The power steering bracket in turn depends on a very rare bolt (with pipe thread, not bolt thread) that screws into the water pump. Since the bracket comes in several pieces ... if you buy a "factory bracket" on Ebay, most of the time you're not getting all the pieces you need. In addition you need the rare two-groove generator pulley and three (!)-groove water pump pulley. Last but not least, adjusting belt tension on factory setups is a bear. The compressor mounts on elongated bolt holes (2 or 3 inches long) and the belt is tightened by SLIDING the whole compressor along the bracket and then tightening the four bolts underneath! Very poor design!
Aftermarket brackets -- These are a simple joy to work with. One single bracket attaches at the water pump, intake manifold, and exhaust manifold. You need an extra crankshaft pulley, but no oddball generator or water pump pulleys. An idler pulley on an adjustable arm makes belt adjustment a one-minute procedure.
AFTERMARKET VS. FACTORY AIR
I hate to use the word "ALWAYS", but yet, in my experience, aftermarket systems are "ALWAYS" better than factory air. The engine brackets are simpler, while still being excellent quality. I believe there is less "big corporation" mentality in the aftermarket manufacturers, and it shows. The designs are simple and to-the-point, not unnecessarily elaborate and evolved.
Aftermarket systems are not only easier to install, they work better! Factory models have the evaporator coil buried deep within the dash, with several feet of ductwork that are superheated in a closed car on a summer day. With the aftermarket systems, you have an underdash coil (usually larger than the factory coil) only 2 or 3 inches behind the vent outlets ... it can't help but be a lot cooler!
THE BASIC A/C SETUP
Your basic classic A/C setup is as follows. The compressor connects via a medium (#8 or 13/32) hose to the top of the condensor (in front of the radiator). The bottom of the condensor connects via a small (#6 or 5/16) hose to the receiver/dryer, and thence continues to the evaporator expansion valve (inside the car). Leaving the evaporator we have a large (#10 or 9/16) hose returning to the suction side of the compressor.
In the 5/16 line between the condensor and the receiver/dryer, you should include a high-pressure safety cutout switch. They didn't exist in the 1950's -- instead, there was a safety blowout plug at the bottom of the receiver/driver. (Well, I suppose it's a little better than blowing out inside the car!)
Electrically you will have auxiliary power connected to the fan switch, which then goes to the fan motor and thence to ground. Also auxiliary power which first goes thru the thermostatic switch, then thru the high-pressure safety cutoff switch, and thence to the compressor clutch.
KISS YOUR 6-VOLT SYSTEM GOODBYE
If you're driving a 6-volt system and worried about keeping your car 100% original, you wouldn't want to install A/C in the first place. You have to drill some holes, and anyway you certainly wouldn't want to quit enjoying everything true 1950's style (meaning sweating all the time in the summer).
But you want to install A/C and think maybe you can still keep your 6-volt system? No, that's not possible. I went thru that stage also. Looking for 6-volt parts for a few years will cure you of this insanity. Just for starters, there are NO 6-volt clutches, and there never were! Guess what? Those early '50's 6-volt A/C setups had solid pulleys on the compressor, and the compressor turned ALL THE TIME! Even in the cold and rain! Even in the winter! Yes, even the 1955 Ford factory air manual advised you to disconnect the pulley during the cool season to "save compressor life"!
No, you have to upgrade your vehicle to 12-volts to run A/C. You want a cycling clutch, and you want to have plenty of juice for your evap blower, and for your auxiliary condensor fan (yes). And for the sake of humanity, you don't want to break down on the freeway during rush hour on a hot day, and your poor old 6-volt system doesn't want to start. People stuck behind you just won't understand ...
CHOOSING AN A/C SYSTEM
Compressor -- I recommend a new, modern compressor such as Sanden. My only concern is with running an important accessory (such as the alternator) from the 2nd groove of a dual-groove compressor clutch. You'd better keep an extra clutch pulley handy in the trunk if you do that. Say the compressor clutch bearing goes bad. On an intelligently designed setup, you just take off the A/C belt and keep going. On a poorly designed system, you can't do that because it also turns the water pump and alternator. Then you're stuck wherever you are, just because of stupid A/C.
INSTALLING OLD A/C UNITS ON OLD CARS
If you're lucky enough to have compressor brackets (factory or aftermarket) for your engine, use them! Chevy 283's and Ford FE engines went all the way into the 1970's, and compressor brackets are relatively plentiful. Ford Y-Blocks went only until 1963, but this was already early in the A/C era, and brackets do turn up from time to time (maybe once every 3 months on Ebay). Other engines such as the Ford Flathead never had factory A/C brackets, but now have enough of a following that modern brackets are made for them (albeit for modern compressors only).
For most other engines from the 1950's, compressor brackets will have to be fabricated, and this is the most difficult part of the project. But if I can do it (on my Ford 223 six), I think any reasonably crazy person can.
Before fabricating a bracket, carefully plan and measure. You need a method of tightening the belt. You can use aftermarket idler arms, sliding bolt holes, or on my 223, the entire bracket pivots slightly.
Ideally the compressor should run off a dedicated bolt-on pulley wheel on the engine crankshaft. These pulleys are usually hard to find, sometimes impossible. For my 223, I placed the compressor where the generator originally went. Then I placed the generator above the compressor but offset one belt-width back. So now the engine crankshaft belt runs the water pump and compressor, and the second groove on the compressor clutch runs a different new belt that turns the generator. It looks a little strange, but I have tweaked it carefully and it's run fine for many thousands of miles now.
If you do move the generator to run off the compressor clutch extra groove, or run the compressor off the same belt as the water pump -- you'd better carry an extra clutch and a clutch puller in your trunk. If that bearing goes, you not only lose A/C ... you'll be stranded. If you get stuck in Lone Pine, for example, they "may" have a few standard parts, but certainly not an exotic compressor clutch.
OLD A/C UNITS COMPARED TO NEW A/C UNITS
More to follow ...