# Thread: Scroll Compressor draws about 10 amps more than it should

1. Originally Posted by Butch1234
yes this is the run capacitor...I may have read the meter incorrectly but that is it...what do you think it should be
Way more than .5 amp! If the cap is good the start winding should be drawing several whole amps!!!!

2. DIY at it's finest!!!! 6 freak'n compressors. All under warranty i assume!!!!! They probally gave him 2 replacements. Then he had to buy the 3rd and maybe the 5th and 6th!!!!

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Originally Posted by Butch1234
thanks for the suggestions.,....on the electrical issues...we installed new capacitors, and start relay, in any case, the measured current on the capcitor leg is only about .5 amp..
The 0.5 amps on the aux winding is way low. My 3.5 ton scroll pulls 7.0 amps. A fractional hp motor might pull 0.5 on the aux winding. All the other theories you have are thin...check the wiring.

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I agree,,,,, my calculation show that this should be maybe 2-3 amps to a maximum of 7 amps depending on voltage drop across the capacitor (which I will measure) using the following formula one can calculate the expected current in the start winding

C in MFDs= (2654 * Amps)/voltage. where the voltage is the voltage drop across the capacitor...so perhaps this is the problem

no these are not under warranty...the folks that sold this system went out of business...I am the bag holder...

once we figure this out I will post a long story on this system...I appreciate constructive ideas and suggestions....we keep you posted

5. Voltage drop across the capacitor? I'm confused!!!As i always read higher voltage across the capacitor!!!!

6. Is this a french system?
Are the in ground pipes plastic coated copper?

7. Originally Posted by Butch1234
I agree,,,,, my calculation show that this should be maybe 2-3 amps to a maximum of 7 amps depending on voltage drop across the capacitor (which I will measure) using the following formula one can calculate the expected current in the start winding

C in MFDs= (2654 * Amps)/voltage. where the voltage is the voltage drop across the capacitor...so perhaps this is the problem

no these are not under warranty...the folks that sold this system went out of business...I am the bag holder...

once we figure this out I will post a long story on this system...I appreciate constructive ideas and suggestions....we keep you posted
2654 is the value used in a 60 hz system. Are you using 60hz?

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Originally Posted by Butch1234

C in MFDs= (2654 * Amps)/voltage. where the voltage is the voltage drop across the capacitor...so perhaps this is the problem
He's no doubt, from Missouri...

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What is the Model number of this unit
What is the complete Model number of the compressor.
What is the total holding charge of refrigerant in this system.
What type of oil are you using.
What is the level of oil in the sight glass when running and when it is off.
What is the temperature of the sump of the compressor and what is the suction pressure.
Have you checked oil for contaminants and has an oil analysis been performed.
What is the Model Number for the Sporlan CPR valve.
What caused the previous compressors to fail and where they opened up to examine failure.
What is the superheat and sub cooling.
Did you install a crankcase heater.
Have you installed a suction clean up filter and how did you clean up the mess.

__________________________________________
Trouble shooting is not part of the repair......understand the symptoms and you will find a solution.

10. Originally Posted by OldSchoolMech

So you check the charge yet?
LOL he still hasn't checked voltage yet!!

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@ butch1234

What is your understanding of the function of a CPR valve?

You say you adjusted it.....do you realize there is a specific way to adjust these valves? You cannot just start cranking around on the adjustment and hope it solves the problem because it won't.

12. He won't answer questions so don't waste your time. He won't even post the model # of the compressor.

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yes it is 60hz 3540 Vac
but more importantly

FIXED !!!!!!!!!!!!!

First I want to thank everyone on this board who gave constructive ideas. As most of you know, when you are dealing with a very perplexing problem it helps to have knowledgeable folks to discuss the problem with. Yesterday, after several posters suggested that the current in the starting winding of the compressor was too low, and my own calculations also confirmed that it should be much higher I went back to take another reading of this motor lead. As I stated before, the first time I took the reading with a clamp on, the meter was up under the control panel part of the unit in the shade and it was difficult to see, I thought I read 0.5 amp but it could have been 5 amperes, I just was in a hurry at the time. Well I went back and checked, this time I got an even lower reading (~0.3 amp !). I looked the wiring over one more time and could see nothing wrong. But I figured I will just replace a short (~10”) factory lead from the secondary side of the contactor to the run capacitor.
So after I replaced this short lead I restarted the unit and it ran smooth. I knew the minute it started that it was working fine. Indeed, the starter winding current was now about 10 amps (the voltage across the run capacitor was about 319 volts, the current agrees with the formula C in MFDs= (2654 * Amps)/voltage, or 80 *319/2654 = 9.6 amps). And the total unit draw was about 24 amps (66 psi suction about 300 psi discharge hot water mode). No more rattle and the correct current. Anyway looking at the wire it looks fine, the connectors (spade female end (slide on)) look fine but there is obviously something wrong with the wire. I want to show this wire to a few folks and eventually we will see where the break is. This was a factory installed wire and as I said, when you look at it you see nothing wrong. I did not spend a lot of time trying to figure out where the problem is but it is obviously intermittent. It measures 0 for resistance (i.e. good continuity) so I suspect there is an internal break that opens when current tries to flow. Anyway, never look a gift horse in the eye, for now the unit is working the way it is supposed to.
When I have some time I will write a long long story of what it has taken to get this geothermal system working. Again thanks for all the help you folks provided.

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