Carrier 5ton dims house lights, seems worse

[aroethli]

We have a 5ton Carrier "Performance Series" Air Conditioner(not heat pump), model number: 24APA560A300

It is about 18 months old.

When the unit starts, it really dims the lights in the house noticeably. And over the last season, it really seems like it has gotten worse, although it is possible that this is our imagination.

The specs on the label are:

208/230V
26.4 rla
134.0 lra
Minimum Circuit Amps 34.3
Max breaker 50amp

We have a 200 amp service, and have a pretty light load. The only other big draw we have is our electric dryer, which doesn't run frequently and doesn't have to coincide with the A/C startup for lights to dim, and our electric water heater.

The breaker is 50amp SquareD, and we have 6 gauge service wire to the A/C unit.

Does anyone have any thoughts on why this unit would be dimming our house lights(whole house) so noticeably, and if it is possible it could be getting worse?

One electrician friend suggested it may be a poor ground, and that a local ground rod for the A/C itself might help.

Another said I should just upgrade to a 400 amp service, but I find that hard to believe.

Any thoughts?

I can provide more info if needed.

Thanks,
Al

[Mr Bill]

Sometimes a shot of nitrous at start up will solve this problem but it could also be a loose connection anywhere from the Light company pole to the a/c outside condenser, or maybe a start assist is due, but I would call a service company before it gets any worse.

[aroethli]

Hi Bill,

Thanks for the reply, and we'll definitely get our electrician out to double-check the connectivity end-to-end. That's a good first step for sure, although I was hoping if there were anything obvious about my specs/setup that didn't seem correct someone might point that out

One question about "hard start" or "kick start" modules though, I think this Carrier may already have an OEM hard start device. It appears as though it has a relay and large capacitor attached in the compressor wiring harness, although I could be mistaken.

Do any OEM units already have "kick start" type modules already installed?

I'd hate to invest in an aftermarket unit if I've already got one.

Thanks,
Al

[Mr Bill]

Hi Bill,
Do any OEM units already have "kick start" type modules already installed?
Thanks,
Al

Yes a lot of them do, but the start assist could be bad or getting bad, a service tech can test with his meter both capacitors, the run cap and the start assist cap.

[beenthere]

You may be seeing the run cap.
You DO NOT need a 400 amp service to run a 5 ton A/C.

As Bill said, even if it has a factory start, it could be bad/weak. You need a tech to check it, and the electrical connections.
How long of a wire run is it to the A/C from the panel box.

[aroethli]

You may be seeing the run cap.
You DO NOT need a 400 amp service to run a 5 ton A/C.

As Bill said, even if it has a factory start, it could be bad/weak. You need a tech to check it, and the electrical connections.
How long of a wire run is it to the A/C from the panel box.

Thanks,

That's reassuring that I don't need a 400A service, and I really didn't think we did.

And just an aside, how much "headroom" for another system can a 200A service typically support with our 5ton already installed? I am looking at a high-velocity system heat-pump for the remaining 1500-2000 sqft of downstairs space.

The service run is probably 20-30 feet.

We had the electrical service redone when the AC was installed, so it is all new.

Al

[beenthere]

That will depend on the size of the HV. And your current total load on the panel.

[geodude]

What kind of system did you have 18 months ago before the new unit was put in?
Sometimes the transformer from the utility company may need to be upgraded or the line from the power pole/transformer to the house up sized.
Had a job recently where we put in a 16 seer 3.5 ton heat pump and had the same problem. The previous unit was an oil furnace. Had an oil furnace before and a 200 amp panel. Called an electrian out and he found that the wires from the power pole to the meter head where they where hooked in to the meter head were cooked and corroded. Fixed that and problem solved!

[firecontrol]

An 18 month old unit should still be under warranty. I'd start with calling your contractor out to have them check it out. Explain what is happening when it starts. By doing a complete checkout they should be able to verify if it's something to do with the outdoor unit or a wiring issue.

[Daltex]

I'm not an electrician but it seems to me that if the AC was the culprit, it would be tripping the 50 amp breaker. The electric co. would be where I'd start. Once it's verified that your getting proper juice through the meter then I start looking at the AC.

[allan38]

Several possible causes.
Since it's dimming the lights upon startup I'd suspect the start assist is bad.
A high resistance connection can cause this too.
And sometime you never know what the problem is until you actually put your test equipment on the unit.
I've found a unit with both a bad start assist and a dead run cap.

[aroethli]

I'm not sure on the warrantee, but I think the labor has expired. I'll have to check with my vendor Monday.

The previous unit was also a 5 ton Carrier, but it had given up the ghost after about 20 years of service. So in theory the supply from Progress Energy is good, but who knows. What are the "magic words" I should use when I call them to get them to really check out the transformer and service lines?

Thanks for all the feedback!
Al

[Shophound]

I live in an older neighborhood. When one of my neighbor's condenser starts, my house lights dim. The transformers on the pole are old and may be getting weak. Either that or that neighbor has one hell of a hard start problem.

I would first have the compressor capacitors checked. If good I would then have a stem to stern sweep of all the electrical connections performed by a competent electrician. If that checks out, the power company may want to investigate the health of their transformer and power lines.