April 23rd, 2014
It was a typical ordinary service call in Carlsbad for a Bosch dishwasher that was stopping in mid cycle. The lady said somewhere in the cycle the machine would just go blank and stop, then start again and then stop and then on and on. I got there, put my clamp-meter on the main line power into the unit and started it up. Bosch dishwashers will energize their heating elements somewhere between 8 to 15 minutes into the wash cycle. When this happens the current jumps from 1.6 amps to about 11 amps as the heater draws significantly more current. (See my blog post on this page about bad solder joints on Bosch control modules)
Well anyway, around 9 minutes in, the current jumps up to 11 amps just as expected, but only a few moments after this occurring, the machine went dead. Lights went out, stopped working and after about 30 seconds or so, it started back up again, only to repeat the same cycle of going dead moments after the heater being energized. So AHA! the problem is in in the heater circuit I surmise. Excess current is causing the control module to shut down or so I thought…
So a new module in slapped in and we try it all again. But oh, No, it’s still happening! What can it be? What’s causing this machine to shut down when the heater kicks in?
Well, it took some time and a whole lot of thinking things through before I figured out what was wrong. These folks had one of those multiple outlet strip boxes under their sink. You know, those multiple outlet, surge protection boxes you get at Dixieline Hardware for 9 bucks? Their dishwasher was plugged into one of those. So after sheer desperation of trying everything else, I pulled the dishwashers plug out of the strip outlet and plugged it directly into the wall outlet and guess what? IT WORKED!
There was nothing at all wrong with the dishwasher. The strip outlet was faulty and would shut down when the current through it went higher. This caused the dishwasher to shut down and then start back up again as soon as the faulty strip outlet reset itself.
Sometimes its so easy to ignore the fundimentals when you’re out on a witch-hunt for the problem you ASSUME to be with the appliance.
Or try this one on for size…
Two days ago, a Fisher and Paykel Dish drawer Dishwasher. Lady said it wouldn’t do anything, no lights, nothing.
She was setting up the back end of an office suite for a studio rental. About halfway through I learn from her that she had new wiring and outlets installed and the dishwasher wasn’t doing anything. (now she tells me…) It was plugged into an outlet that supplied power to a Gaggenau two burner studio cooktop which was working. So as with all no power complaints I start at the source, and placed my pocket voltage probe
to the power line and it glowed, so naturally I presumed that the problem was inside the dishwasher, so start following the voltage trail till you hit the end right? Voltage inside the dishwasher was 62 VAC. Isn’t that odd? Shouldn’t it be 120 VAC instead? And curious that 62 is just about half of 120… Well, cut to the chase. Turns out that the household 120 VAC standard electrical wall outlet was defective, but only HALF of it was bad. The other half was running the cooktop with no problem. Prove it! Ok, Swap the plugs on the outlet. Now the dishwasher runs but the cooktop doesn’t. Had to be one for the books, A standard household electrical wall outlet that’s half bad. Close examination of the defective outlet showed nothing externally abnormal, Could have been installed by an electrical contractor or an inept husband and neither would have been the wiser. Oh and by the way, the cause was an open neutral line. I found this out using a wall outlet tester
Both of these nifty little devices are a must have for just about anybody that owns a home. It will pay for itself many times over, and they’re cheap; about 8 bucks each.