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1966 Cadillac Air-condition Compressor

Started by EAM 17806, January 23, 2011, 07:07:01 PM

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EAM 17806

Is it important to disconnect the wire connection to the air-condition compressor during the winter months so the compressor will not be turning thereby reducing some stress on the engine?  Some say with the A/C switch off the affect is the same. We realize the pulley is still turning either way but what affect does both ways have, if any? 
Ev Marabian

1976 Cadillac Coupe DeVille, 1989 Chevrolet Caprice Classic, 1990 Pontiac Bonneville and 1996 Buick Skylark

Tim Groves (Cadillac Tim)

On the 66 Cadillac the a/c compressor clutch is engaged at all times except when the dash control is on OFF, or if the outside temperature is below 32 degrees.  The compressor switch located in the RH kick panel opens when temperatures are freezing or below, stopping current to the compressor clutch.

Obiously when the compressor clutch is engaged, there is more load on the engine than when clutch is not engaged.  How much reduction in gas mileage I'm not sure, but it will reduce it some with the clutch engaged.

Tim

"Cadillac Kid" Greg Surfas 15364

Ev,
There is no question but that disabling the compressor (by unplugging the compressor lead in wires) will reduce the load on the engine.  The load itself is minor, somewhere around 3/4 horsepower during the winter conditions you are talking about.  On a '66 the procedure for setting the idle speed up actuator is to put the car in neutral, turn on the ac, and adjust the idle speed via the speed up actuator to 900 RPM.  When adjusted thus, and the car is placed in drive with the compressor on the idle speed usually balances out at just over 500 RPM, so it is obvious there is a load.  In the summer time that load will go up to over 5 horsepower on a hot, humid day, and that is the primary reason for setting the idly up.In the winter if you want, you can disable the compressor, however you loose one of the major attractions of the ATC system, the ability to dehumidify the air, and on a cool, wet, rainy day with no compressor in operation to dehumidify the air, you can end up in a hot swamp for a car.
A good running '66 is good for 11 to 12.5 MPG, and overall, the AC will "cost no more than .5 MPG if that.
Just like some folks turn off the water to the heater core in the Summer to get "ice cold air" you can turn off the dehumidifying functions of the system by leaving the refrigeration system off, but again, you cancel the beauty of the Cadillac Automatic Temperature Control for what must be an insignificant return.
Greg
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

The Tassie Devil(le)

But, isn't it a fact that if something is not used regularly, it will fail in the end?

And with A/C, all the manuals I have read state that the A/C has to be used at least once a month for 1/2 hour to lubricate the internals.

A bit like Free Wheeling Hubs on a 4 wheel drive vehicle.    Leave them free all the time, and when you need to use the 4 wheel Drive to get out of a situation, the chances are that the front diff will fail due to rusted teeth etc..

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

"Cadillac Kid" Greg Surfas 15364

As always Bruce, you bring up the valid point which, in combination with what I said above is additional reason not to disco9nnect the compressor.
Greg
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-