Packard Forum Index » Pre-War (1899-1942)

Keith, I am amazed by the technical sophistication of this early prototype after comparing its properties with the AC which was offered as an option 6 years later.

The 1939 version suffered from several problems:

West Peterson and Dave (O_D) will confirm that there were no controls on the instrument panel; the system ran constantly. Turning it off meant to stop the car, lifting the hood and removing a belt. A system for almost $300 has been operated by dirty hands! But the 1933 prototype "...may be turned on or off at will from the instrument board or rear seat..."

Packard (as well as ZIS) mounted the units to the trunk, reducing cargo space. The protptype instead was underfloor mounted.

Because the AC units were rear-mounted with inoutlet tubes behind the rear passenger seat, it (probably) wasn't unusual for condensation to collect above rear-seat passengers. It would then drip down, staining clothes. Meanwhile, little air reached the front seat. Now take a look to the first version that delivered fresh air to the center of the car.

Unlike later systems, the 1939 weather conditioner units didn't pull in any outside air, a problem in an era when many people were smokers. How about the prototype? "...Air is drawn into this system through a concealed inlet, filtered to remove dirt and dust...".



[central theses & formulations:http://blog.nwautos.com/2012/07/chill_out_air_conditioning_has_come_a_long_way.html]

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The condensation issue maybe debateable. Maybe someone can verify condensation problems in the very early AC units of the 30's-40's.

With a possible exception of very high dollar cars with AC such as Cad, Linc, Rolls, MB etc my memmory tellls me that AUtomotive AC units ca 1970 - 2000 used striclty reciculation of cabin air. Not fresh air.

There is a problem with fresh air AC. Especialy in high humidity conditions when condensation is quick to form. Low humidity does not present a problem.

Let us not confuse early (prewar) recirc HEATERS with post war fresh air heaters with AC of any era. IIrc it was NAsh ca. 1948 that offered the very first FRESH air heater in the US. Possible exception would be exh. manifold heaters offered on Ford model 'A'.

Fresh air heating is a different world from fresh air AC.

As for filtering the air in a car for smoke and dust and pollen and so-forth is somewhat of a moot point. Moot in the sense that many people, whether they admits to it or not, are more than willing to lay up under the AC in their HOUSE while smoking 420, frying bacon in the kitchen, floral arrangements in vases around the house and keep the house so air tite so as to allow little fresh air into the house thus causing mold etc, etc, etc.

Or to put it another way:, not too many people ever complain about smoke blowing in their face on a friday nite at the local titty bar.

I mite add:
Common garden variety HOSEhold AC here in the eastern US (i don't know about other countries or high rent areas of the US) are recirc AC units. Not fresh air. True for heating too, not fresh air. Or have i just been slumming all my life???

Most household units are filtered and recirculated unless the AC is of the swamp cooler variety.

Majority of cars up until the early 60s and any with hang on units were mostly recirculated. Packards own 55-6 system would do either. If you just turn AC on, then recirc but if you move the left fresh air vent knob to "cold" position, 100% outside. Trunk units were recirculated. The pair of nominally sized outside air vents provided a bit of fresh if the owner manually opened them. The controls for the vents were on the package shelf so doubt if they were played with much.

After the early 60s, the majority of factory in dash jobs started using fresh air drawn from the cowl area as normal supply. Most had an extra button labeled fast cool or something along those lines to close the outside door and recirculate. Downside to the recirc on those systems was no temp control and the blower noise increased substantially since it was generally on the highest speed.

A few systems did have an actual recirc button where you could vary temp and fan but the noise level was still a bit higher that would be present if outside air was used.

Here are pics of an 88 Ranger control panel. One with AC the other without.

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Quote from post #24 above:
"Most had an extra button labeled fast cool or something along those lines to close the outside door and recirculate"

Yes, and according to my factory authorized 89 Caprice (also covering BPO) indicates recirc air ONLY on max setting of AC control. On the lower settings some of the air is outside air.

The only thing i will note is that on very hot days (over 90 degrees F) here in middle Tn. positioning the control at anything less than max is about worthless.

One of the problems i run into in any car with AC is attempting to operate AC at anything less than max cool. As i'm driving along the compressor will kick off and on frequently. At max cool it doesn't.

The Packard with Mark IV ac has evap coils visible from the drivers seating position. The frequent off/on of the compressor clutch is coincidental of ice forming on the evap coils. At that point i check the outside air vent control lever for open position.

That clutch bit was the cheap way out for OEMs -- both for fuel efficiency and for cost since they could eliminate some components and raise the CAFE number with one quick change. A lot of the aftermarket mfgs had always used it for cost reasons.

Remember some pre 60's thru early 70s systems where the clutch was engaged all the time AC was on. Evaporator temp control was by POA valve, suction throttling or the like where the evaporator was kept at a constant just above freezing temp all the time -- 40 degrees or so. Ice couldn't form yet with evaporator being cold, air never got humid. Heater went all the time as well so after air was cooled and dehumidified, it was partially reheated to a comfortable temp controlled by the blend door per the operator setting.

With the gas crisis and cheapening the system in the mid 70s they got rid of extra components sometimes down to just an orifice instead of even an expansion valve. Cycling the clutch takes the load off the engine for a few minutes so fuel economy was boosted.

The clutch thermostat is supposed to cycle when the evaporator gets to just above freezing but usually around 35-38 degrees or so minimum. Air flow also is supposed to help keep evaporator relatively stable. In the several minutes it takes for evaporator to warm to start the cycle over, water will drip off the coils, air will get well humidified and since many still use a form of blend door, you feel a bit of heater warmth as well until the clutch kicks in and cools again.

If yours is icing up, wonder if your thermostat might be acting up or air flow is somehow restricted.

The evap temp control brings up a question on the heat powered units. Think refrigerators just turn on/off the small burner when needed. Wonder how hard it is to control the heat applied to the refrigerant material if residual heat is used or if there is another way to control evap temp. Maybe some kind of bypass system like they used in the early days?

A refrigerent bypass for the convection type or i was thinking more along the lines of heat riser type valve to expose heat or reduce heat.

I would not think the plumbing for the AC lines thru or around the exh manifolds would be any kind of a problem. Not since the mfg'ers seem to have no trouble plumbing Turbochargers, smog tubes, catalytic converter, etc etc into the exhaust manifolds.