While troubleshooting an issue with my downdraft range vent external blower unit (Kitchenaid KPED829K. ~20 years old. Motor model: ebm-papst R4E310-AL15-10 ) I noticed that the start and run capacitor wiring seemed unusual. I thought I'd post a question to see if there is an explanation that I have overlooked. I am unable to find an official wiring diagram for this model but I did draw a diagram (below) of the actual wiring, and another of what I had expected to see.

The unit seems to run fine and the only issues that I have had with it is that it is a bit slow to get up to full speed and once it is running the kitchen and living room lights (LED) flicker a little or a lot depending on which speed I select using the variable speed switch. I suspect (hope) the flickering lights may mostly be due to a aging variable speed switch which I will soon replace, but I am really not sure.

I tested both the start capacitor (16uF +/- 5% @ 250V) and the run capacitor (7uF +/- 5% @ 250V) and they are both within tolerance.

This is the current wiring setup:

actual wiring

This is what I had expected to see:

expected wiring

I have no idea whether this was installed this way or changed either intentionally or unintentionally during a repair somewhere along the way.

Are these two methods of using a run capacitor equivalent?

Is the run capacitor actually doing anything for the motor?

Is this unsafe in any way?

Is the run capacitor possibly contributing to my flickering lights (I have no idea why that would be but I figured I'd ask)?

UPDATE 1: Confusingly, I found a similar model (KPED892K) that has those same two capacitors (16uF and 7uF) and a manual disconnect button in its part list but the over simplified wiring diagram (figure 3, page 4 of the installation manual) for that model only shows 1 capacitor and uses different coloured wires coming from the motor which sort of indicates an undocumented wiring harness connected to the wires coming from the motor... based on the diagram provided by @Bryan I'm thinking U1 goes to black, U2 goes to white, Z goes to one side of the capacitor, PE goes to ground). ...but no sign of that second capacitor in that diagram.


1 Answer 1


The connection diagram for the blower motor you specify indicates a single run capacitor in a normal configuration:

snip from blower datasheet page 9


There's no way that the run cap AND the start cap are doing something in the way you've found it wired. There's two options there: either the installer was having a moment, or perhaps you've chased out the wiring wrong. I would have another look (though I suspect you already have) and experiment with putting the caps in according to the connection diagram and your own good sense.

  • \$\begingroup\$ Thanks @Bryan. I wasn't able to find that document, but I had found an AP15-11 model which had that same diagram. I had assumed it was a different spec therefore had different capacitor requirements so decided to ignore it. I double checked the wiring again (from a photo)... it is not even close to what that document specifies. In fact, it looks like U1 is hooked up to Neutral and U2 is hooked up to Line so it appears to be wired backwards... but i haven't confirmed that the black wire coming from the house is Line and white is Neutral (perhaps that's backwards too). \$\endgroup\$ Sep 4, 2022 at 20:52
  • \$\begingroup\$ @AllainLegacy I actually found that data sheet by googling the motor, clicking on the similar data sheet and then substituting the real motor model into the URI - and it worked! Do report back on your experiences with this setup, I’m interested to hear what happens. Also does this motor really have a manual start button? \$\endgroup\$
    – Bryan
    Sep 5, 2022 at 17:12
  • \$\begingroup\$ I am hoping to find some time to work on it this week. I will post an update. The motor itself doesn’t have a start button but there is one wired into the overall blower unit assembly. Not sure why because to get at it you have to remove the external cover and if you are doing that you should probably disconnect power altogether. \$\endgroup\$ Sep 6, 2022 at 11:41

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