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setting window unit a/c


I have a small window unit a/c. I bought it almost 20 years ago and other than having to hand-start the fan to get it going once, it's been fine.

Now that it's hot here, I'm running it 24/7. My question is, is it better to set it so that it remains cooling constantly or set it so that it stops cooling periodically? With this heatwave it has only stopped cooling early in the morning. It shudders when it stops cooling and starts up so that is my concern. I would think letting it run constantly would be better for it than having the cooling/compressor turn on and off. My apt stays nice despite the mid to upper 90s we are having and doesn't get too cool when things cool off at night so I'm comfortable letting it run.

What do you think?



John L

Re: setting window unit a/c

Every motor needs some rest, a chance to cool down. You know that heat is the main cause of motor breakdown.

At 20 years old, your A/C unit is ready to quit, and slaving it 24/7 will make sure it dies doing what it loves to do.

Start shopping around for a new air conditioner, if you can find one. Most outlets around here are sold out.

Re: setting window unit a/c

OK, thanks.

Re: setting window unit a/c

As a former HVAC contractor I would rather see the AC unit run 24/7.

The reasons are

1. better temperature / humidity control
2. the hardest thing for any electrical device to do is start up.

This is based on the conditions that the freon charge is full and both coils and filters are kept clean and properly serviced. The compressor motor is designed to be cooled by the freon inside the unit and when the compressor starts the oil level inside the compressor takes a few minutes to stabilize after starting.


Re: setting window unit a/c

I'm with Mike5785 on this one. Motors like this are designed for constant duty and the hot environment they are in. Especially with capacitor-start motors, the highest current drawn is on start-up and it is the over-current that burns out motor windings moreso than constant heat. But yeah, if you've got to start the fan by hand it's time for a new one or at least a repair on the fan. I've seen near-ancient AC's and window fans that ran fine all summer long once they got started but were sluggish to start.

My Mom's US-made window AC is about 20 years old and still working fine. I hesitate to replace it as I built a custom panel for it that fits her vinyl windows well with the sash in place so that it can slide closed during the winter. The new cheaper imported AC units won't last that long- you get 4-5 years max with most of them, often less. The last one I had stopped cooling well after 2 years and wasn't worth fixing.

If the OP's unit were mine I'd see if I could finagle some lubrication to the fan bearings or replace them. That might get you a few more years out of it. Then again I'm about as cheap as they come and I hate spending money when I don't have to :cool:


Re: setting window unit a/c

Thank you both. I think I like running it 24/7 better. I worry about the shudder it gives when the compressor starts up seems being the most stressful point in it's use. Yeah, it's hot out too. I'll just have to hope it can handle that.

I've hand-started it only once. I doubt I can lubricate it though. I'm on the second floor and it's hard to get to.

The unit is a Carrier LCA061P. Real small. I love it.

I'd be curious what you think of these factors:

It's on a 20 amp circuit breaker that has two other outlets on it. (All of the circuits are 20 amp breakers. There's a 100 amp main and a 50 which I think is unused or is the boiler.) The microwave and toaster oven are on a different breaker but I turn the cooling off when I use either, just to be safer. (I never use the two at the same time either.) That's the only time it isn't cooling. I keep the fan running though; I don't turn the unit off. It takes a few minutes to do whatever cooking I need to do so it works out that the compressor is off for at least two minutes, as the manual recommends that I don't turn it back on without at least two minutes to go by.

I have noticed that a laser printer on the same breaker (but different wall plug) has affected the a/c when the printer starts up. The printer must draw alot when it first comes on as the a/c unit gives a shudder when it comes on. The rest of the time it's fine and no lights dim at any time as far as I can tell. I rarely use the printer anyway, but it's effect on the a/c is a concern.

The a/c draws 6 amps and 665 watts.
The laser printer draws 7.8 amps
I have a stereo receiver that is on the same circuit which draws 4.5 amps (550 volt amps). Even though I should have plenty of capacity left, I am being very careful and not using the stereo much when the a/c is on.

So, between cooking and the printer, those are the only electrical system challenges to the a/c.

I'd be curious your thoughts.

Re: setting window unit a/c

Thanks LIPWAK for this conversation

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