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Low voltage at clutch
Posted: Tue Aug 09, 2016 9:21 pm
by jeepsj
In diagnosing everything, I'm only getting about 11v to my compressor clutch. Could that be part of my clutch slipping problems? Where should I start looking to find the voltage draw?
1987 Chevy R30, 7.4l.
Re: Low voltage at clutch
Posted: Tue Aug 09, 2016 9:28 pm
by emsvitil
You could rewire it so that the existing wire to the clutch turns on a headlight relay that then gets it's power directly from the battery.
Re: Low voltage at clutch
Posted: Tue Aug 09, 2016 10:29 pm
by Dougflas
verify your meter is reading correctly by measuring the voltage across the battery. If it is ok, look at your grounds. Leaving the negative at the battery post and then measure the voltage at the clutch. If still low, go to the clutch relay. Measure the input. If low, trace backward to find the drop. If ok, measure the output of the relay. Find the problem before trying to modify around the problem.
Re: Low voltage at clutch
Posted: Wed Aug 10, 2016 7:08 am
by Cusser
jeepsj wrote:In diagnosing everything, I'm only getting about 11v to my compressor clutch. Could that be part of my clutch slipping problems? Where should I start looking to find the voltage draw?
1987 Chevy R30, 7.4l.
Is this measured with the engine running? Or with engine "off" ?
Re: Low voltage at clutch
Posted: Wed Aug 10, 2016 10:02 am
by jeepsj
Cusser wrote:jeepsj wrote:In diagnosing everything, I'm only getting about 11v to my compressor clutch. Could that be part of my clutch slipping problems? Where should I start looking to find the voltage draw?
1987 Chevy R30, 7.4l.
Is this measured with the engine running? Or with engine "off" ?
Engine running. Tested with my meter ground attached to battery.
Re: Low voltage at clutch
Posted: Wed Aug 10, 2016 10:10 am
by GM Tech
clutches are programmed (GM anyway) to cut off at 10.5 system volts to save the engine from stalling- give it reserve battery power when losing voltage- as in a bad alternator. So 11 volts to the clutch won't cause your slipping issue- clutches don't slip until about 7 volts or so-- been there done those experiments with external power supply...but 11v is not as good as it should be-- should be near system voltage-- what is your system voltage running? at the battery with engine running?
Re: Low voltage at clutch
Posted: Thu Aug 11, 2016 1:45 pm
by jeepsj
Found some corroded connectors and cleaned it up and now have 13v at the compressor with engine running. Battery voltage is about 14v.