Quote:
Originally Posted by bgilly
Amp values are not accurate either since voltage variations directly influence amp draw; the lower the voltage from name plate the higher the amps, the higher the voltage - lower amps. Not every power outlet is going to be right at 120 volts ac.
A unit very low on refrigerant will have to work harder and also cause the compressor motor to run hotter therefore pull more amps, so amp information can be helpful for indepth troubleshooting.
Bobby
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The amp draw check is relative to outside ambient temperature, not line voltage. The compressor amp draw shown on the name plate is at 95 degrees. The change in amp draw is 1 amp for every 10 degrees shift in temperature, plus or minus. A compressor that is stated to draw 12A @ 95 degrees will draw 12.5A @ 100 degrees, 13A @ 105 degrees, etc. This is for a correctly charged unit. I don't know if this would also apply to residential or comercial units, I havn't asked, but this comes from Dometic, not me, and it is how they will tell you to check one of their units for proper charge without having to tap into the system with a piercing valve. If the unit is low on charge, it will draw less than the stated amerage, so an undercharged unit actually works less because of the reduced charge. I was skeptical when I was first told about this, but I've checked it against a couple of units and it does work. I serviced one last Saturday that wasn't cooling and it was drawing around 6.5A. I sweated in a shraeder valve, evaciated it and weighed in a charge and checked it again, and the amp draw was within .1A of where it was supposed to be.