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HVAC Question: Loud Hum, no fan (1 Viewer)

Jobber

Footballguy
I apologize for the new thread, but I'm not a search ninja like some around here.

Hot as hell yesterday and we noticed that the central AC seemed to be on, but was not blowing cold air. I went outside to the unit, and the fan blades were not spinning. And there was a somewhat loud humming. Before I call the local AC guys, does anyone have a diagnosis and approximately how bad I'm screwed?

1999 Carrier Puron unit.

 
More than likely a capacitor. With a service call, should run you about $250.

Granted, it could be several things. Just be hopeful it's not your compressor.

Could also be a condenser fan motor, which should be about $600-$700.

 
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And if you ever need any advice on replacing or if you are getting screwed, just run it past me first. I'm in the business and have been for the last 12 years or so. Mainly on the residential side.

 
Had that same thing earlier in the year for my upstairs unit. Went from capacitor to fan to entire unit. It was as old as yours too. 

 
IIRC, for us the same thing happened and it was the condensation pump in the attic.  The pump had a safety switch that would cut the AC unit off when the water in the reservoir reached a certain level. 

 
 Same thing happened to me a couple years ago and it was the capacitor. It was actually pretty easy to replace, as I just followed a YouTube video and it cost me about $20 total. 

 
 Same thing happened to me a couple years ago and it was the capacitor. It was actually pretty easy to replace, as I just followed a YouTube video and it cost me about $20 total. 


FYI, I think this is the video I used at the time, since the guy is very thorough.  Definitely try the stick test (about 4 minutes in) and see what happens.

 
So, worst case is a replacement unit. I'm a below average FBG so my house is only about 2100 sq ft. What tyoe of unit is recommended? I know they'll push me toward the Cadillac, but I just want something that'll last 20 years and do the job. 

It does get a little warm upstairs in the afternoon and evening though which is worth mentioning.

 
So, worst case is a replacement unit. I'm a below average FBG so my house is only about 2100 sq ft. What tyoe of unit is recommended? I know they'll push me toward the Cadillac, but I just want something that'll last 20 years and do the job. 

It does get a little warm upstairs in the afternoon and evening though which is worth mentioning.
my goodman units work well.....

 
More than likely a capacitor. With a service call, should run you about $250.

Granted, it could be several things. Just be hopeful it's not your compressor.

Could also be a condenser fan motor, which should be about $600-$700.
Chiefd couldnt he verify if it is a capacitor by removing the metal fan cover, turning on the unit, and when it starts to hum, manually turn the blades with a piece of cardboard or something else?

 
So, worst case is a replacement unit. I'm a below average FBG so my house is only about 2100 sq ft. What tyoe of unit is recommended? I know they'll push me toward the Cadillac, but I just want something that'll last 20 years and do the job. 

It does get a little warm upstairs in the afternoon and evening though which is worth mentioning.
Well, you are in Minnesota, so get a 95% efficient furnace. For your air conditioner, get something like a 14 seer air conditioner. Its a step up from the minimum required by law.

Anything over that is a waste of money in your climate. 

If it comes to that, just let me know what they are recommending and the costs and I will let you know if they are high or not.

 
Chiefd couldnt he verify if it is a capacitor by removing the metal fan cover, turning on the unit, and when it starts to hum, manually turn the blades with a piece of cardboard or something else?
The easiest way to tell this is to remove the service panel where the main electrical line goes into the AC. The capacitor will be there with some other wires. It looks like a cylinder - kind of the size of a smaller beer can. If it's bad, it will be swollen. So it will look like a beer can that has expanded.

Oh, and pull your outside disconnect before you check this.

 
Just had the exact same thing happen to me about a month ago, and it was the capacitor. I carry the home service plus plan with my power company (about $25/month), so the fix was free and it took the service guy a grand total of 5 minutes to diagnose and replace it.

 
I also had capacitor blow and fixed for $25. It looks like a small pop can, and if blown it will look obviously misshapen. Google is your friend. 

If the capacitor is fine next likely culprit is the motor on the fan. You can buy a new motor for around $200 and if you are handy you can replace yourself. I have done this repair twice (different homes) and it is straight forward.  Grab a meter from hardware store and see if you have power to the motor leads. If you do and the fan is not spinning that is the likely cause. 

 
FYI, I think this is the video I used at the time, since the guy is very thorough.  Definitely try the stick test (about 4 minutes in) and see what happens.
I took out the old capacitor and ordered a replacement off of Amazon for $11. It is a little bulged at the top and bottom so yeah, you guys were correct in the diagnosis. Thanks!

 
I took out the old capacitor and ordered a replacement off of Amazon for $11. It is a little bulged at the top and bottom so yeah, you guys were correct in the diagnosis. Thanks!
That's good news, but get ready: your unit is 18 years old and you're playing with house money. Be prepared just in case the rest of it starts to crap the bed shortly.

 
Had the same thing happen to me.  Replaced the cap, to no avail.  Called an AC repair guy and it was the compressor...  Replaced it instead of the whole unit since it would have needed a crane to get it onto the roof of my rowhome (thus requiring street closure and a permit).

I also recently replaced the blower motor in the air handler in the basement.  Was tough to find the exact correct part (1 HP ECM motor with end bell), but bolted right on and worked like a charm.

 
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ChiefD said:
Well, you are in Minnesota, so get a 95% efficient furnace. For your air conditioner, get something like a 14 seer air conditioner. Its a step up from the minimum required by law.

Anything over that is a waste of money in your climate. 

If it comes to that, just let me know what they are recommending and the costs and I will let you know if they are high or not.




1
I immediately thought pricing that would make one say, "Are you high or something???"  :lmao:

So cool with the advice, ChiefD.

 

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