Open Amp Sensor error in GD compressor

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Air Compressor

Repair guides for air compressors.

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Rav @rav60893

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게시됨: 2026년 3월 26일

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Open Amp Sensor error in GD compressor

Hi

I am working on Gardner Denver Compressor model Electra Saver.
I recently came across an error message Shutdown 'Open Amp Sensor'

This error message popped up within few minutes upon turning on. There is a light on the Compressor motor as seen in above pic, don't know what it means. The motor doesn't get hot.

After pressing Reset & then Constant run, the compressor runs, in most of the cases - all day. But sometimes it stops after running for few hours with above error message.

I tried to look thru the manual but couldn't find above Error message.
Any thoughts what this error is for & how to fix it?

Thanks

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jayeff @jayeff

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Hi @rav60893

Here's the operating and service manual that may help.

Go to p.68 (78 of 82 pdf) in the manual, to see what to check when there's an Open Amp Sensor message.

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Thank you so much jayeff for sharing the appropriate manual. I was referring an incorrect one. I followed the Parameter on page 68. The manual says MONITOR SFA (looks like a typo). It's seems it should be 'MOTOR SFA; found on Page 25/82. Will work on it tomorrow .

Rav 의 2026년 3월 26일

Per the manual, CN-4 has 2 wires connected, probably the Current Sensor.

I will try to find the current transducer & CT.

Otherwise, is it ok to bypass it by simply disconnecting it and then thru Program -- Configuration Adjustment --- set MOTOR SFA to '0'?

Rav 의 2026년 3월 31일

@rav60893

I don't know, never worked on this type of compressor.

It's interesting to note that none of the wiring diagrams show anything connected to CN-4 whereas CN-3 has all the transducers/thermistors shown connected. (see p.52- p.54/82)

It does state: "If not installed, set the “MONITOR SFA” to zero amps in the configuration adjustments" so I suppose you could disconnect it and set Motor SFA to 0 and check .

Just be ready to turn it off quick, if necessary ;-)

I think that this may be the parts list but maybe check first and if it is , find the part number for the current transformer and transducer and search online for Gardner Denver (insert the wanted part number) to find a supplier - see p.50/58, p.52/58 & p.55/58 for the one that is applicable to your compressor. Usually part numbers are on the part itself if you wish to verify

jayeff 의 2026년 3월 31일

Hi jayeff

Upon checking I noted there is a CT attached on the motor Contactor wiring. The CT wires are connected to Transducer & its output is connected to the Control board via CN-4 connector. Though, the wiring diagram doesn’t show anything connected on CN-4!

Assuming it’s 0-10Vdc output from transducer, with compressor running, should I expect between 0 - 10 Vdc OR 10Vdc?

Rav 의 3일 전2026년 4월 6일

@rav60893

See the Amp Sensor Failure section on p.21 (1/82) where it says that the amp sensor is an "optional extra". If there is none then it's functions are disabled.

Could be a varying voltage depending on what the compressor load is at the time but this is only a guess.

You could always measure it and check what it is with the compressor running

jayeff 의 2일 전2026년 4월 6일

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Thank you so much jayeff for sharing the appropriate manual. I was referring an incorrect one. I followed the Parameter on page 68. The manual says MONITOR SFA (looks like a typo). It's seems it should be 'MOTOR SFA; found on Page 25/82. Will work on it tomorrow . — Rav
Per the manual, CN-4 has 2 wires connected, probably the Current Sensor.

I will try to find the current transducer & CT.

Otherwise, is it ok to bypass it by simply disconnecting it and then thru Program -- Configuration Adjustment --- set MOTOR SFA to '0'? — Rav
@rav60893

I don't know, never worked on this type of compressor.

It's interesting to note that none of the wiring diagrams show anything connected to CN-4 whereas CN-3 has all the transducers/thermistors shown connected. (see p.52- p.54/82)

It does state: "If not installed, set the “MONITOR SFA” to zero amps in the configuration adjustments" so I suppose you could disconnect it and set Motor SFA to 0 and check .

Just be ready to turn it off quick, if necessary ;-)

I think that this may be the parts list but maybe check first and if it is , find the part number for the current transformer and transducer and search online for Gardner Denver (insert the wanted part number) to find a supplier - see p.50/58, p.52/58 & p.55/58 for the one that is applicable to your compressor. Usually part numbers are on the part itself if you wish to verify — jayeff
Hi jayeff

Upon checking I noted there is a CT attached on the motor Contactor wiring. The CT wires are connected to Transducer & its output is connected to the Control board via CN-4 connector. Though, the wiring diagram doesn’t show anything connected on CN-4!

Assuming it’s 0-10Vdc output from transducer, with compressor running, should I expect between 0 - 10 Vdc OR 10Vdc? — Rav
@rav60893

See the Amp Sensor Failure section on p.21 (1/82) where it says that the amp sensor is an "optional extra". If there is none then it's functions are disabled.

Could be a varying voltage depending on what the compressor load is at the time but this is only a guess.

You could always measure it and check what it is with the compressor running — jayeff

Air Compressor

Open Amp Sensor error in GD compressor

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