Refridge ice maker is not working and diagnostics advise looking at the water valve solenoids. I am to use a ohm meter to check the continuity of the solenoid. So I took my battery powered continuity tester (pin on one end and clip on the other) and tested the good solenoid and nothing came up. So I am guessing that continuity of a solenoid does not mean a simple continuity. I made some guesses from research, and would you explain?
1. Ohm is resistance of a load (in this case, the solenoid windings). We assume continuity of the windings, that the wire is not damaged somewhere, because the windings show resistance (that it is in working condition)?
2. I am purely guessing that solenoid windings has one end where current goes in and another end for current to come out, that the winding is one continuous wire. So why doesn’t the continuity tester glow?
I will buy a multimeter and test for resistance, but I would really appreciate some explanation about the difference between resistance/continuity and the simple continuity. I hope I asked a right question. Thank you in advance.
By the way, the water valve has 2 solenoids. One is working, supplying drinking water. Ice maker is not getting any water so I am assuming the other solenoid is kaput. I can’t say for sure until it is tested with a meter. If the meter shows proper resistance then the fault may be in the ice maker itself. But still, I am curious about resistance vs. continuity. Thank you.
Replies
typical 120 vac solenoid is near 1000 ohms, varies with size and make, ice maker solenoid should be fairly high.
Your pin tester (the type with a small light bulb I assume??) typically has a 1.5 V bulb and 1.5 V battery. For the bulb to glow, I'm guessing about 0.1 amps to see the glow in a lit room.
I=1.5/1000 = only 1.5 mA, hence you do not see a glow.
Get yourself one of the $3 HF meters, that will work fine for your solenoid measurement.
solenoid
Thank you for the explanation. I knew the answer had to be simpler than the head spinning guesses I was making.
I went and got a multimeter before I read your post. But I wanted one for a while. I will look into HF meter as well if that is all I will need for some appliance repairs I do around the house. Again, thanks.
One thing to be wary of with typical digital multimeters is measuring the voltage in regular household AC circuits. You may, eg, be trouble-shooting a 3-way switch and discover that one of the wires carries about 50 volts. In other cases you may find that a wire seems to carry about 100 volts when disconnected.
What you're seeing in these cases is "phantom voltage", caused by capacitance in the wires. The extremely high input impedance of the multimeter (on the order of several megohms) will "read" electrical charge picked up through the air by a long wire. But put any sort of a load on the wire (a resistance of, say, 100K ohms) and the phantom voltage will disappear.
(But note that this phenomenon isn't of importance when trouble-shooting a fridge, since the wires are all relatively short.)
Thank you for all information. Trying to avoid hyperbole, but everyone's help did focus all the loose information I was reading from the web. I do hope to learn some more about diagnosing residential electrical system, namely troubleshooting wires and dead outlets and such. I am hoping the multimeter will come in handy then. Again thank you.
Yeah, the typical solenoid wiil have from a few hundred to a few thousand ohms resistance. A battery-and-lightbulb tester likely won't light up. With your typical needle-type meter this resistance bring the needle to roughly mid-scale. (Obviously, with a digital meter the resistance will read off directly, but pay attention to the decimal point, and any range indicators such as "M" -- million -- or "K" -- thousand.) Anything much higher than a few thousand indicates the coil is "open" (your fingers will have a few K resistance, so take care to not touch the probes if your measurement is over about 1000 ohmo). Anything much lower than 100 indicates a short (except for current-sensing relays).
FWIW, resistive heaters (toaster elements, oven elements, water heater elements, etc) will have very low resistance -- from about an ohm to maybe 100 ohms. Very hard to tell if such an element is shorted (which is rare), but generally your simple lightbulb tester will tell you if it's open. Sometimes it's hard to get a good contact on such things, and you'll have 5-10 ohms of contact resistance on top of the 1 ohm element resistance. (Here you use your fingers and squeeze hard on the contacts, or press tightly with the pointed tips.)
What type of icemaker is it?
http://fixitnow.com/appliantology/typeoicemaker.htm
If it is a whirlpool (the most popular, used by a dozen brand names) I would bet the head is bad. That is the timer plate with all the contacts, cam and timer motor. I usually fix things but I have had zero luck fixing a bad timer on these things.
That will cause missed things like the water fill, the thing may also stall in mid cycle with nothing going on.
There are 2 pins you can short to force a cycle to watch it but you may have to block the door switch or unblock the photocell if this is a "icebucket on the door" model.
That link has some pretty good tips if you poke around.
The last time I bought one Midwest Appliance parts had the best price but shop it. I have fixed 4 of these and every one had a bad timer so that is a weak link.
It came with Kenmore about 14 years ago. Applianceaid.com lists it as old style Whirlpool ice maker, also used by GE, etc. Modular types ? are supposed to have holes where contacts or circuits can be tested but not this. It did look like the replacement head enables testing. Thank you for your help.