Window unit just quit....questions....

Joe Reed · Jul 13, 2017

I have a Kenmore window unit (18,000 btu cool/12,000 heat) that I installed through the wall of my standard 2-car garage in November 2008. It's only used occasionally whenever I'm working out there in cold weather - or hot (like today!). It's worked fine until today...when it completely quit putting out cold air. It's just recirculating ambient temp air - which is about 87 degrees in the garage (99 outside).

First question: What is the most likely cause of a sudden failure like that, and can it be a DIY fix? FWIW, I can't hear the compressor running....just the blower. The coils and filter are clean.

Second question: Given cost of labor and parts, should I just trash this unit and get a new one (prob. around $600 or so)? Although the unit is almost 9 years old, it actually only runs a total of a month or two a year - if that.

Third question: If I decide to see if repair is feasible, do typical HVAC repair techs do these units, or do I call an appliance repairman?

Fourth and last question: I have an 11,000 btu window unit in the attic that was barely used. I *could* stick that in the wall in place of the bigger unit for the time being but there is no 120V outlet close by. Anything wrong with swapping out the outlet and 40 amp duplex breaker for the appropriate parts - and utilize the existing wiring? It, of course, would be overkill on the wire size - but that would let me go back to a 240V unit later on...

bczygan · Jul 13, 2017

Go to store.

Take CC.

Bill

Joe Reed · Jul 13, 2017

Can I borrow yours?

wasfuzz · Jul 13, 2017

Just don't let Bill drive you in his Van, it wont start when you get there!!! :evil:

bczygan · Jul 13, 2017

wasfuzz said:
Just don't let Bill drive you in his Van, it wont start when you get there!!!

That IS 2 for 2 on longer trips, now that you mention it!!!

Bill

KRB52 · Jul 13, 2017

Check the wiring to see if some little furry critters didn't get in and start chewing, or that over the course of time some corrosion has hampered the compressor circuit.

An HVAC tech may be interested in this, but put you off until November or December; the summer it usually their busy season for A/C work. An appliance guy may be able to tackle it, but I would be surprised to see that they had the equipment needed to safely (and legally) remove and replace the refrigerant.

Joe Reed · Jul 13, 2017

Could it be a capacitor? I know I've had a couple of caps go bad in the house central unit...causing the compressor to not start. That is, of course, assuming window units also have a cap....and it's easily replaced...

chrispyny · Jul 13, 2017

Window units DEFINATELY have starter caps and i bet all the money in your wallet that the problem is in fact your starter cap.

Get into the unit, find capacitor, search online for replacement, purchase, install and enjoy!
Btw, the caps are like $11 online and VERY common.

Google "starter capacitor window a/c"

Joe Reed · Jul 13, 2017

I believe you may be right. I just looked up the parts list online and found where it's located. Sears has it....for $61. Repairclinic.com has is for about half that, but they're out of stock. Partsimple.com has it for $26. Never bought anything from them, but there's always a first time

Zexx · Jul 13, 2017

Read the label on the bad cap and get the voltage and micro farads (μF) then just buy a regular start cap that has similar ratings and the correct type of terminal. You will need to match the micro farad rating, but can go the same or higher on the voltage rating, best not to go too much higher though. (no 440v cap on a 240v system)

Joe Reed · Jul 13, 2017

Pulled the unit out far enough to get a look at the cap. It's not expanded like so many failures, but that doesn't mean it's not bad. It's certainly worth $30 or less to try to save the unit.

That thing is a ***** to get to....especially since the unit is hung high on the wall. Lots of wires & connectors crammed into the control box along with the cap.

On my central unit this is a 10 minute job...remove one panel and the cap is right out in the open. On this window unit I'm pretty sure the cap was item #1 on the assembly line and they built the rest of the unit around it. :sad:

crazy wheel · Jul 13, 2017

Zexx said:
Read the label on the bad cap and get the voltage and micro farads (μF) then just buy a regular start cap that has similar ratings and the correct type of terminal. You will need to match the micro farad rating, but can go the same or higher on the voltage rating, best not to go too much higher though. (no 440v cap on a 240v system)

Why not?

Most capacitors (that are used in air conditioners) have a voltage rating of 370 or 440 volts.
Do you know why?
Do you know where this 370 or 440 voltage comes from?
BTW it is perfectly fine to use a capacitor that rated for 440 volts in place of one that is rated 370 volts.
But not okay to use a 370 volt in place of a 440 volt.

Joe Reed · Jul 13, 2017

I'm just going to order the original LG/Kenmore part. For $26 I'll be sure I get the right one. It's a 4 terminal cap...

Ohmthis · Jul 13, 2017

I wouldn't order anything until I knew it was bad. Do you have a good meter? Do you know how to check the capacitor? It could be the capacitor (they commonly go bad) but also look to see if there is any corrosion on any of the plugs. I've seen a bad relay on the control board too. These unfortunately are made to be throw always now. There aren't any service ports for refrigerant and sometimes not many parts for em either.

Zexx · Jul 13, 2017

crazy wheel said:
Why not?

Most capacitors (that are used in air conditioners) have a voltage rating of 370 or 440 volts.
Do you know why?
Do you know where this 370 or 440 voltage comes from?
BTW it is perfectly fine to use a capacitor that rated for 440 volts in place of one that is rated 370 volts.
But not okay to use a 370 volt in place of a 440 volt.

Mainly because in my experience the higher voltage the cap is rated for the higher the cost, no reason to spend more than needed.

Marctrees · Jul 15, 2017

My first step would be to confirm that T stat is functioning..

Either w Voltmeter, or temp jumper the T stat.

Marc

CGVet · Jul 15, 2017

If the T stat is good. then pull the caps out (obviously mark them first) be sure to short them across the terminals first, or you might be in for quite a shock, then take them to any good electric motor shop, they will be able to test them for free and they will have generic replacements at a reasonable price without the wait and hassle of mail order and be able to confirm that you need one or both (many systems have 2)

crazy wheel · Jul 15, 2017

crazy wheel said:
Why not?

Most capacitors (that are used in air conditioners) have a voltage rating of 370 or 440 volts.
Do you know why?
Do you know where this 370 or 440 voltage comes from?
BTW it is perfectly fine to use a capacitor that rated for 440 volts in place of one that is rated 370 volts.
But not okay to use a 370 volt in place of a 440 volt.

Zexx said:
Mainly because in my experience the higher voltage the cap is rated for the higher the cost, no reason to spend more than needed.

Shouldn't be any cost difference.
Let me help out answering the other questions I asked you.
The higher voltage is induce voltage, like a transformer.
In a PSC motor there are 2 windings.
Each winding is a different length and diameter, wrapped around an iron core. Like a (setup) transformer....
This creates the higher voltage, therefore the capacitor must be rated to handle at least the amount of voltage that is created by start windings.

The voltage rating on the capacitors is the maximum voltage that the capacitor can handle. So it is perfectly fine to use a 440 volt in place of a 370 volt capacitor.

As for the uf rating, it's best to keep it the same as the original. A 50uf could be used to replace a 45uf in a pinch. But not a 10uf in place of a 5uf....
For whats its worth, if you do replace a smaller capacitor with a higher rated uf, it would be a good idea to write the rating of the original capacitor inside the unit. Then the next time the capacitor fails, it will not be upsized again and again

crazy wheel · Jul 15, 2017

Marctrees said:
My first step would be to confirm that T stat is functioning..

Either w Voltmeter, or temp jumper the T stat.

Marc

Good advice.
Some T-stats on window units use a thermistor. Some you can disconnect the thermistor from the control and the compressor will run

Joe Reed · Jul 15, 2017

Lots of good advice here. FWIW, the unit was working just for early in the morning. The garage was plenty cool, so I turned the fan speed lower. After a while it was getting warmer...and that's when I realized I had turned it down to the "Fan Only" setting. I switched it back to the "Low Cool" setting and the compressor never restarted.

Don't know it that points to any problem in particular....and it's too hot today to mess with it. I did already order a cap since they weren't expensive. I'm sure if it's a bad compressor or board the cost of replacement (& labor) would be high enough to warrant just buying a new unit.

mikebaker1129 · Jul 16, 2017

crazy wheel said:
Why not?

Most capacitors (that are used in air conditioners) have a voltage rating of 370 or 440 volts.
Do you know why?
Do you know where this 370 or 440 voltage comes from?
BTW it is perfectly fine to use a capacitor that rated for 440 volts in place of one that is rated 370 volts.
But not okay to use a 370 volt in place of a 440 volt.

^This is 100% true !
+ or- 10% microfarads is an acceptable amount in a pinch,but it is best to use the correct size.

LS6 Tommy · Jul 16, 2017

CGVet said:
If the T stat is good. then pull the caps out (obviously mark them first) be sure to short them across the terminals first, or you might be in for quite a shock, then take them to any good electric motor shop, they will be able to test them for free and they will have generic replacements at a reasonable price without the wait and hassle of mail order and be able to confirm that you need one or both (many systems have 2)

Shorting a run capacitor is a very good way to kill it if it wasn't already bad... It should discharge as soon as the unit is turned off anyway.

Tommy

Joe Reed · Jul 20, 2017

Ha! It WAS the cap! :bounce:

I now have cold air flowing into the garage again. Got the cap on Tuesday. Would have had it Monday but UPS decided to deliver it to someone on another street with the same house number

Maybe that's their business plan for cutting costs....just drop the stuff off in the neighborhood and let the neighbors do the final delivery. :headscrat

The cap wasn't as difficult to install as I thought at first glance. Working on a ladder just made it a slight bit more difficult.

It's nice to save a $600+ ac unit with a $38 part..especially since I've never worked on an ac unit before!

sourdough · Jul 21, 2017

Delete. You got it fixed. Good for you!

Window unit just quit....questions....

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