Home AC makes loud buzzing sound

[themechanic]

Turn it off, pop the covers, check out the contactor.. .. clean it, give it a hit, what ever it takes.. turn it back on. See if you can keep her running, otherwise you're asking for bigger issues.

WILCO.

 

[toolmanmike]

Yep.. why I put a 1.5 ton in a 6000 square foot house!

I was sizing up a new boiler for my house and did a Manual J study and contacted a HVAC engineer on line. I also asked about ac. I sent him all the specs and he looked at where I live. He said if my A/C runs constantly for 2 or 3 days during the hottest days of the summer, the unit is sized perfect. It runs long enough to keep the humidity low. My old house stays very comfortable at 77° and 50% humidity.

 

[GrabberOrange69]

Turn it off, pop the covers, check out the contactor.. .. clean it, give it a hit, what ever it takes.. turn it back on. See if you can keep her running, otherwise you're asking for bigger issues.

...agree and lots of costs. Your unit has R22, and it will be expensive to fix (probably need to find a small time a/c company, because all the national companies will want to replace with a R410 unit).

Hopefully an easy fix.

 

[hunt2elk]

I'm going to guess that the motor capacitor is bad. The motor looks like it is not spinning nearly as fast as it should be. Shut off the power and open it up. A lot of times when a cap goes bad it will bulge out on the terminal end.

 

[dadsbee]

I was sizing up a new boiler for my house and did a Manual J study and contacted a HVAC engineer on line. I also asked about ac. I sent him all the specs and he looked at where I live. He said if my A/C runs constantly for 2 or 3 days during the hottest days of the summer, the unit is sized perfect. It runs long enough to keep the humidity low. My old house stays very comfortable at 77° and 50% humidity.

Purposely undersized mine for the same reason. 90F out and it pretty much runs constat to keep the house at 73. If it gets to 100F outside it will slowly climb to about 76 in the house and is not keeping up until night time and we get things back. Humidity stays below 45% even when it's 90% outside.

 

[themechanic]

I'm going to guess that the motor capacitor is bad. The motor looks like it is not spinning nearly as fast as it should be. Shut off the power and open it up. A lot of times when a cap goes bad it will bulge out on the terminal end.

WILCO

 

[toolmanmike]

Purposely undersized mine for the same reason. 90F out and it pretty much runs constat to keep the house at 73. If it gets to 100F outside it will slowly climb to about 76 in the house and is not keeping up until night time and we get things back. Humidity stays below 45% even when it's 90% outside.

Perfect....

 

[themechanic]

Thanks everyone. It is the contactor, again. Lots of critters, egg pods, etc in there. I push down on the top and the buzzing goes away. Will replace the contactor tomorrow if I can buy one locally. The earwigs are bad this year. They like the dark places. I'm going to puts some insecticide on the yard this week.

 

[Beekeeper]

Looks like the fan isn’t running at full speed check the start capacitor and as stated the contractor for the fan.

 

[khryslerkid]

Short across the capacitor terminals to drain the voltage that's being stored. You'll get a good jolt if you make contact with the wiring on the contactor when replacing it if you don't.

If there's a disconnect outside make sure you pull it. Otherwise find the breaker. Good luck!

 

[Slap Stick]

1.5 tons for 6k sq ft is much too small. Your a.c. shouldn't run all the the time if is the right size.
There is a formula for figuring a.c. size for your size area.
My home is 1k sq ft and had a 2 ton unit. It ran constantly set at 78. This month I had the entire system replaced with a 2.5 ton unit. It runs much less even set at a lower temp and the humidity is still 20-25%.

 

[sloinker]

Replace the start/run cap at the same time as you replace the contactor. Cheap insurance for a part that has a relatively short service life and is cheap to buy. Cheaper than a motor and better than a week of waiting for a new install in a 94 degree house.

 

[themechanic]

New contactor is in with zero noise.

Thanks FBBO

 

[dadsbee]

Nice! My Miller has been running for 24 years and I've never had as much as the disconnect box open.

 

[themechanic]

Mine is a mid 90s Rheem.

 

[Ranger16]

I've replaced the contactor once since 1980. Mine is Singer. Still got the original furnace and Rheem water heater as well. How long can my luck last?

 

[Slap Stick]

You are due to find out this winter!

 

[bm02tj]

Please note it is not the size of the AC it is the CFM per ton
slow fan down to dehumidify