Pagoda SL Group
W113 Pagoda SL Group => Electrical and Instruments => Topic started by: mjp8877 on September 07, 2007, 09:45:23
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Hi. I have a 1971 280sl. Whenever I turn on AC there is a drain on battery and I cant restart the car. The battery is good. The alternator is new (35 amps as recommended in original model). We put in a new voltage regulator but it only got us 1 more amp to work with. The mechanic is recommending a new alternator this time with more amps than was originally on the car. If I dont run AC there is no problem. AC checked out OK. Anyone with any suggestions? Mike
Michael J. Price
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Michael
Will the car restart if the a/c switch is turned off?
Unlike most cars that had factory installed air conditioning, the Frigking unit that was dealer installed in these cars doesn't have a compressor cut out relay that disconects the power to the compressor clutch when the starter is cranking. Having the compressor engaged adds a lot of extra load onto the starter motor when the A/C is switched on.
I agree with the mechanic too, a 35amp alternator is too small for a car equipped with A/C. I remember the 280s as having a 55 amp alternator, most modern cars have a 85 amp or larger alternator, usualy 100 amps.
Maybee a combination of adding a clutch cut out relay and more chaging capacity is what you will need to get your car starting properly.
Al Lieffring
66 230Sl
Jones'n for a new gas tank
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quote:
Originally posted by al_lieffring
Michael
Will the car restart if the a/c switch is turned off?
Unlike most cars that had factory installed air conditioning, the Frigking unit that was dealer installed in these cars doesn't have a compressor cut out relay that disconects the power to the compressor clutch when the starter is cranking. Having the compressor engaged adds a lot of extra load onto the starter motor when the A/C is switched on.
I agree with the mechanic too, a 35amp alternator is too small for a car equipped with A/C. I remember the 280s as having a 55 amp alternator, most modern cars have a 85 amp or larger alternator, usualy 100 amps.
Maybee a combination of adding a clutch cut out relay and more chaging capacity is what you will need to get your car starting properly.
Al Lieffring
66 230Sl
Jones'n for a new gas tank
Michael J. Price
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Michael,
Check your switch also; if it's burned out or wonky it could cause your problem too. I had mine replaced last spring...
Trice
1968 280SL US, signal red/bl leather, auto, kinder seat
Sarasota FL; Alsace France; Switzerland
Think of your Pagoda as a woman with a past...
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When I run car with ac on, then turn off motor I have to jump start battery to get it going, even if I switch ac off. I guess I will go along with mechanic with an alternator with more amps than was on the original car (35 amps)
Michael J. Price
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Trice
"Check your switch also". Do you meen the A/C Switch on the A/C unit?
Roman
Northern Virginia
280 1969,Signal Red, Auto