Window AC unit not running, dimming lights, voltage drop


Old 08-13-04, 06:50 AM
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Angry Window AC unit not running, dimming lights, voltage drop

Hi all, first time poster, long time lurker.

Just moved into an apartment, so I have limited ability to rewire and/or access the mains to check things out thoroughly.
We installed a small window AC unit (6000btu), and had it running as a fan. when we switched it to cooling, it didn't kick in the compressor, but it did start making a different noise. just not the right noise. If it were a car, I'd say it wasn't turning over.
When this happens, all the lights on the same circuit go dim.
I threw a multimeter on the line to watch what happens, the base voltage is about 116, when I hit the cooling mode, it drops to around 90V.

My question is this: is it the unit or the wiring?

We've had the AC unit for about 2 years, and just drove it 400 miles in the back of a rental truck, so it's had a bit of abuse, but should still work. It wouldn't be the end of the world to replace it though, but I'd rather not replace it if the same thing is going to happen with the next one.

advice please!
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Old 08-13-04, 07:27 AM
Join Date: Sep 2000
Location: United States
Posts: 18,497
A drop from 116 to 90 is pretty severe. It suggests a high-resistance connection somewhere on the circuit. High resistance suggests high heat. High heat suggests fire.

The voltage drop is also probably causing the A/C to not function correctly.

Here's an experiment. Unplug the A/C and try the same voltage test at the same receptacle with a hair dryer, and then with a vacuum cleaner. If you get the same voltage drop with all three appliances, then contact your landlord and insist that an electrician check it out.
Old 08-13-04, 07:28 AM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Try the unit on another circuit, in another apartment, somewhere else. See if the unit works properly. Rule out the unit, or decide that the unit is the problem.

You can also tryo to borrow an air conditioner from someone else to see if the circuit is the problem.

By the way, you don't have limited ability to rewire you have NO ability to rewire. As you are a renter you cannot do anything, your landlord must do everything, via an electrician.
Old 08-13-04, 07:46 AM
Andrew's Avatar
Join Date: Apr 2003
Location: USA
Posts: 936
After ruling out the other suggestions--
You might need to replace the start capacitor on the compressor, or add a hard-start kit. Check with a appliance service center for more details.
Old 08-13-04, 08:03 AM
Ed Imeduc's Avatar
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389

AC unit for about 2 years, and just drove it 400 miles in the back of a rental truck, so it's had a bit of abuse,
and only 6000 btu.

Id just get a new one. I dont think a start kit will help here. Ill bet you got the comnpressor off its spring mount inside the can and its shot.

My .02 cents

Old 08-13-04, 09:10 AM
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
Based on your description,A defective capacitor in the "Start"-circuit is a definite possibilty. Capacitors are connected via leads with "push-on" crimp-terminals, so the replacement is not too difficult.

Good Luck & Enjoy the Experience!!!!

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