DIY testing washer/dryer AIO components, do I need a better multimeter

natticus · Dec 23, 2023

Hello,

I have an all-in-one washer/dryer unit and it is giving me error codes. I have the manual that describes how to test the various components on the control module, but the introduction to the Component Testing Procedures section has me a little confused. It seems to contradict itself by stating that I need power attached but need to make sure no power is attached. Honestly, I just plan on testing the resistances and for that I know I'm not supposed to have power, but in some of the component specific instructions it seems to want me to have power supplied to the unit. My biggest question has to do with the suggestion that the tests should be performed with a VOM or DVM with a sensitivity of 20,000 ohms-per-volt DC or greater. I have an innova 3320 multimeter and would like to know if I need to purchase something with higher sensitivity?
I've attached a screenshot of the introduction as well as screenshots of the testing instructions, such as they are, for the two components that are giving me error codes. One component is the Wash NTC and the other is the Water Pump(listed just as pump in the chart pictured).

Thanks!

Avo Mk8 · Dec 23, 2023

The instructions suggest, as you say, that to do the resistance testing, you must switch off and unplug the machine for all the resistance tests.
There are some other checks shown that are not resistance tests (eg middle pic - "running the main motor with AC voltage test") where you obviously have to connect the mains to do the test. To me it makes sense!

Your meter has an input impedance of 10 Megohms, which will be fine.
An old style meter would have an input impedance depending on the range it was manually switched to, but as yours is autoranging it appears to have a fixed impedance of 10Meg. It's equivalent to an old style meter of 20k ohms/volt switched to its 500V range!

natticus · Dec 23, 2023

Okay, thank you. The language just threw me because it was, you MUST remove power, then it says to test, as in the middle pic, with power supplied.
And thanks for the info on the multimeter. I kept getting conflicting information using a web search. Some saying 10 Megohm input impedance meant 10k ohms/volt and others saying it was fine for the same reason you have stated, so I wanted to get advice straight from the horse's mouth, so to speak.

I appreciate the help.