Smart people unite! Electrical question.

[OZMDD]

I have an older window unit in my sunroom that I framed into the wall when I remodeled. It is outdated, but very effective and not easily removed without trim/sheetrock/paint repair, which I don't want to do.

Over the weekend it stopped working well. I determined that it is cooling/compressing fine, but the blower motor is not spinning up to full speed, so it is only moving a tiny bit of air. When I first played with the switch, it went back to normal for an hour or so, then resumed its current status, which has remained unchanged despite all manner of switch jiggling.

The unit is a 230V a/c AND heater. (Montgomery Wards!)

Question: Since the fan motor is still functioning, does that indicate the problem lies elsewhere, like a capacitor or switch(es)? What tests can I perform? I own a Fluke meter and I've already been able to access the motor, if I need to remove it. The control panel area is a bit more concealed, but I can get in there too, if needed.

Before I pull the motor, I wanted to get some expert input.

[POS Racing]

Do you have a wiring diagram on it??

I'd bet it is just a bad blower motor. Can you measure voltage to the motor?

Monkey Wards just re-branded stuff they never made anything. Also I know you live down in DeSoto so you guys may not be aware that Montgomery Wards isn't in business any longer.... Any clue on who the original manufacturer was??

[OZMDD]

No Monkey Wards??? Who has been taking all my charge card payment checks?

I'll see what I can determine from the placard inside. so, a bad motor can still function? I wasn't sure if they just died completely or faded away like Jimmy's sex drive after waffles.

[POS Racing]

Well if the fan is to get say 110 volts and you are seeing 6.5 volts then you can trace it back to the issue. Could also be the fan switch itself.

Montgomery Wards Electric Avenue FTW!!!

[OZMDD]

Thanks! I'll check that first.

[Davidss]

You're going to have to tear it apart. It may or may not have start and run capacitors. So for starters I would take it apart enough you can trace the wiring from the fan switch to the motor. Post that when you have it. Also get the part numbers for the caps/motor. It may be easier just to go on ebay and throw parts at it.

Are you sure it's not frozen? If it was it would be cold but not blow any air. That would be a symptom of low freon charge.

[OZMDD]

Nope, not frozen, the symptoms are the same even though its been off for days. I can see the coils clearly. I can also see the turbine fan, and its spins up, but doesn't go to "full speed." I could tell right away, since the sound is different.

I'm certain that the blower is the issue, just not sure where the fault lies.
IMAG0182.jpg

[goofygrin]

IMO since you worked on the switch and it started working, I'd focus my investigation there. Either the switch is corroded or there's some bad wiring in there related to the switch. Either a bad/broken solder joint, bad switch, etc. Ohm out the switch, test voltage on both sides of it, etc.

[onething]

Buy the squirrel some better kibble.

[boisking]

Take the front panel off and give it a look. Maybe you just need to clean a couple decades worth of dust out of there.

[OZMDD]

Unit is clean. I've been pretty diligent about cleaning and replacing the intake filter, and I had it serviced about 6 years ago.

I have gotten all the way into it, and found a wiring diagram inside! I tested several contact points, and was able to make the unit replicate the issue. I also managed to get it blowing at full strength for a short time, but not quite sure how. I'm pretty cautious around 230V, especially in this old unit with lots of exposed contacts.

I will remove the control switch tomorrow and clean it thoroughly with contact cleaner and see how that does. After that, I'll pull the fan capacitor and get a close look.

I was able to check impedance across both caps (other is for the compressor), and the fan cap is reading 80 ohms, the larger compressor cap is 12ohms.

Also, when the fan was running at the limp speed, i was getting around 228v across the cap, then when it kicked up to full power for a bit, it was putting out the full 338v. Process of elimination should get me to the culprit soon enough. I'm tempted to just replace both parts, but I'd rather know what went bad.

Any thoughts on those cap impedances?

[goofygrin]

A cap's resistance should change as it charges (think of a cap as a small [or in some cases large] battery).

[OZMDD]

Yeah, i knew that once upon a time. Lol. Pulled the cap today; its swollen at the sides, so I'm going to pick up a fresh one in a bit. The switch looked fine, and I cleaned it really well with contact cleaner, no change. All of the switch positions test good for continuity and consistent resistance, so I'm pretty sure its fine. Might grab a new one anyway. Thx all.