# Simple way to detect if an A/c motor is on

**URL:** <https://forum.arduino.cc/t/simple-way-to-detect-if-an-a-c-motor-is-on/370045>\
**Category:** General Guidance\
**Created:** [March 4, 2016, 9:43pm UTC](https://forum.arduino.cc/t/simple-way-to-detect-if-an-a-c-motor-is-on/370045 "2016-03-04T21:43:38Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![KrisKasprzak](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/kriskasprzak/32/221987_2.png) [@KrisKasprzak](https://forum.arduino.cc/u/KrisKasprzak)\
**Post date:** [March 4, 2016, 10:02pm UTC](https://forum.arduino.cc/t/simple-way-to-detect-if-an-a-c-motor-is-on/370045/3 "2016-03-04T22:02:40Z")

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Thought about that, but i don't have one and my project is super temporary--hence 0 cost is ideal.

Basically my fridge is running odd and i want to monitor temperature and when the compressor is on. I've got a thermistor measuring temp and plotting temp every min on an LCD display (and saving the data to and SD card so I can plot temp vs time over say 3 days), but i'd like to plot compressor on/off with temp as well--hence why i need to determine when it's powered up.

I'll just give it a shot.

Thanks for responding.

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