Air Conditioning - Dimming lights when A/C kicks on

Hi guys,

We just had new oil hot air furnace and central A/C installed. Today was the first day/night we had it running. As part of the install, the installer brought in an electrician who wired the new furnace and outside A/C unit. He ran new wires and put in new circuit breakers in the main panel. The installer hooked up the low voltage wiring himself (thermostat, any thing else?). Now the lights dim throughout the house whenever the unit kicks on, right as the blower begins to run. The house was built in 1886 and had a variety of wiring types when we bought it. In Oct 2004 we had the elec service upgraded to 200A, status of all visible wiring checked, grounded outlets (or GFI) installed thoughout, knob-and-tube removed wherever possible and a sub-panel installed in attic just for extra capacity to the upstairs if we need it later. Only some knob-and-tube overhead lights in walk-in closet and hallways remain. Anyway, with the service change, many new wires run, new low-voltage accent lights added with several transformers, etc. System was upgraded knowing that A/C would be added this spring.

So, why are the lights dimming when the A/C blower starts? I'm tempted to turn on the heat and see if it dims when blower starts then too. Should this be happending and, is it dangerous? Are the power surges bad for electronics/computers, etc?

BTW, we had central A/C installed in our last house (ca. 1725, elec had been upgraded to 100 A) by the same guy. We had the same light dimming and when I asked an electrician, he said the house was old and that it was to be expected. I've been to a lot of other houses with central A/C and I've never noticed their lights dimming...

Sorry for the long post--just trying to give all info...Appreciate your help!
JMM

This could be a number of things I would first call your power compny first. It maybe your connection between the meter and the house

Like Scott says it could be several things. The dimming I'm sure is from the start up of the compressor.

Where is the a/c breaker in the panel?? I've found that it's best to install it at the very top of the panel to reduce light dimming.

Another thing that will help is a start capacitor. It will give the compressor the extra boost it needs for start up without taking it from your lights.

The breaker is near the bottom of the panel, but I can see the wires feeding the breaker are punched through the side rather than fed through the top like the rest of them. Does that matter? I would have expected the lights to dim when the compressor kicks on, but doesn't that usually happen a minute or two before the fan? The lights are definitely dimming when the fan kicks on. And about a start capacitor--where would it be located, how big, etc. Is it possible I already have one?
--thanks for replying

Might have them check the amp draw on start of AC. The compressor might be a tight one and need a start kit put on it.

ED :thinker:

"The compressor might be a tight one and need a start kit put on it"

I agree with Ed


HiltonTech

Thanks for the replies, but excuse my ignorance. Is the "start kit" the same thing as a start capacitor or something else?

I've called my local electrician, the one that did all of the work six months ago, not the one that installed the A/C. Can he put the start kit in?

A hard start kit includes a start capacitor & relay, usually all in one "container". I would suggest calling the A/C guy rather than the electrician. Electricians are very good at what they do but most are completely lost once they get into the workings of an A/C.

Where the wires go into the breaker panel don't matter side or top. Hard start kit will probably fix the problem.

http://www.xxxxxxxxxxxxxxxx-surpris.com/.dtc

Forum Monitors Note:
link to obscene picture has been removed.
Member banned.

OK guys,

Thanks for the good info. I don't know who posted the obscene picture here in my thread...and it is in French, so I can't even be sure what it says...not that I want to know...only a jerk would do something like that!

I googled "Goodman hard start kit" and noticed that people put these in for older compressors that may be having trouble starting up. Mine is brand new, out of the box less than a week. It is a Goodman, air being delivered with an AirEase furnace blower motor. As I mentioned lights dim when it kicks on. Given that my system is new, is a hard start kit the best solution? Or shall I have the breaker moved up in the circuit panel? Or both?

You guys are great. thanks for your help. and sorry for the obscenities--hopefully the moderator will get rid of that last post.

ISS