Posted by HH56 On 2019/8/13 8:40:59
Actually, the belts had to be removed to completely disengage the compressor when AC came back in 53 and 54 too. With prewar units it was just part of the yearly changeover. Belts off in winter and heater shutoff valve turned on to allow hot water flow into the heaters. In spring it was the reverse, belts on and heater valve off. Hopefully the weather co-operated fully and any of the in between days where you either froze or sweltered were few and far between.

Packard suggested removing the belts in winter to completely eliminate the evaporator from being cooled. On the 40 units Packard also tried to put the heater in the same box so I suppose it was more important to remove the belts on those cars. The heater apparently did not work very well in the same unit so was removed for the 41-42 cars. Since the units were in an enclosed box in the trunk, even if the evaporator was cold there was no air circulation without the blower running. I suppose you could actually leave the belts on year round as long as you did not mind the extra drag of the compressor. This was particularly true in prewar systems since there was no outside air path into the unit. Postwar, it got a bit more problematic since there was ducting to bring fresh outside air into the unit and if one of those air valves was not closed then driving down the road could force air thru the unit and a bit of cold air entered the car. In theory extra cooling did not happen in postwar units even with the compressor running because those units had an electric solenoid valve and if the AC was off the refrigerant was shunted around the evaporator and could do no cooling unless there was some kind of problem in the solenoid valve or plumbing. Prewar units had a mechanical valve for the shunting so there was no absolute turn off without removing the belts.

From all accounts I have read the AC could freeze you out so in that respect it worked very well. Packard ads say the car with AC was like blowing air over several tons of ice. Since there was only a single air outlet in the middle of the package shelf air flow to the driver was not the greatest so like the post war units, to get the driver and front seat passenger cooled off the rear seat passengers were in an ice box and also had to listen to the sound of the air being forced thru the outlet just behind their heads. Once the car interior was cooled then the blower could be slowed down and was a bit quieter. The cold and dehumidified air was definitely better than any alternative even it if was not quite perfected.

Anxiously awaiting archiveman's book for the additional tidbits he will undoubtedly turn up.

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