Open the back panel:
Remove the 4 screws and the ground wire.

Locate the 2 strip heaters.

Measure the current (amps) on both strip heaters.

HOW TO MEASURE THE CURRENT WITH A MULTIMETER :

1. Set the mode to current (amps) by turning the selector knob to: A∼ and choose the scale that the value is expected to be in. (The ∼ stands for alternating current.)


2. Put the clip of the multimeter around the cable you want to test.


3. Read the value on the screen.


4. Remove the clip of the multimeter from the cable.