It was a good day. I learned several things.
Pushing in and then pulling out the MAX COOL or FR Cool buttons on a ’64 300K, at least, turns off the compressor but leaves the various doors in place. The FR COOL button controls and opens the cowl air inlet door so the system would continue to supply nice fresh, cool outside air (if you are lucky enough to have this scarce commodity available at your locale). The MAX COOL button would leave the “doors” in place but the vents would only receive recycled air from within the cabin from near the front firewall. Firm shutoff of the heater control valve is obviously necessary in order to get the coolest air.
Early 300’s (’55-’56) had trunk-mounted evaporators and air handlers (supposedly N/A from the factory in 1955 But I believe a few were produced on Special Order. A/C was available on other Chrysler sedans of the period, but not the ’55 C-300. Fresh air was admitted through cool little pods mounted on top of the rear fenders. I don’t know where controls for the “doors” of these pods were located—possibly in the trunk—but not on the dash. Mechanical and electrical connections looked like a plumber’s nightmare.
I found this on the “net”:
How powerful are automotive air conditioners? Most sedans have air conditioning systems that can approach 40,000 BTU (3.3 Tons) in capacity. A typical 3,000 square foot house can easily be cooled by a 36,000 BTU (3 Ton) system. Cars need massive cooling capacity in order to quickly bring down the interior temperatures on hot days (easily 130 degrees F) to comfortable levels (70-75 degrees F) in a few minutes. Houses, on the other hand, only need to handle temperature variations of about 15 degrees.
I have seen higher refrigeration tonnage figures for automobiles—up to 5 Tons. The important point is that air conditioning a Chrysler 300 requires about the same cooling capacity as an average-size house. A rule of thumb is that it takes about one horsepower/ton to drive a compressor and blower fan. Considering that on a level road with no wind it only takes about 10-20 HP to move the average car at 60 MPH, the impact on fuel economy is measureable but the engine will readily adopt to the increased load of the A/C in our brutes. Small-displacement rice burners will probably note a reduced capability of maintaining speed on hills. With a trip computer giving current MPG, I have measured the difference at about 1 MPG. Published references quote 5-25% reduction in MPG which is still more efficient than lowering all the windows due to increased drag.
Larry’s South Lake Tahoe meet motto on the shirts was C(3)00L referencing the range of Letter Cars. They are all COOL, but your favorite is MAX COOL.
…and did you know that when you press the FR COOL button and pull it out again it disengages the compressor and allows fresh outside air into the cabin through the AC vents? Just sayin’.
Webster rules and says:
noun: motor; plural noun: motors
a machine, especially one powered by electricity or internal combustion, that supplies motive power for a vehicle or for some other device with moving parts.
Engineers and purists must live with consensus. Alan asked what does one call the turbine that drives the generator at the dam. It is a motor, as is the air-powered device that the dental hygienist uses, the windmill that pumps water, the treadmill that the animal trots on to power another device, a steam engine and that belchfire 8 in our brutes.
It was interesting to learn that there is a filter in the sealed pulsation dampeners/mufflers on either side of the air conditioning compressor. On the suction side, it is a final filter to prevent solid trash from entering the compressor. It could conceivably become plugged if some extenuating circumstance created a lot of solid foreign material in the evaporator. Similarly, if something broke loose in the compressor, a filter on the discharge side would prevent the trash from travelling downstream and plugging the capillary tube or expansion valve.
Last point: I have the HVAC switch out of our ’64 300K and it is only set up to operate the A/C compressor clutch when either the MAX COOL or FR COOL buttons are pressed in. Pressing in the DEF button does not actuate the clutch. There is also no apparent low-pressure cutoff or thermally-controlled switch in the clutch circuit. You press MAX COOL or FR COOL and the A/C compressor will be engaged. Later design resulted in using the A/C system to dehumidify defrost air and inserted a protective switch in the clutch circuit to disengage the compressor in case of loss of refrigerant.
Posted by: "Rich Barber" <c300@xxxxxxx>
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