Air Conditioning is broken in home

spidey07

No Lifer
Aug 4, 2000
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Any clues? I'm going to skip work to get repair out here tomorrow. The fan on the AC unit isn't turning and the unit is making a humming/whining sound. It happened yesterday and I turned it off for a while and it started up just fine but that's not working.

The fan appears to be a direct drive, so no belt. I'm only talking about the fan on the AC itself, not the air handler/central air.
 

Rubycon

Madame President
Aug 10, 2005
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CAC has two parts. Is this on the indoor unit or the outdoor unit?

Most common causes of fans not turning are seized bearings (they should be lubed!) and a bad start capacitor if the motor has one.

Saw your edit.

Try using a ruler to see if the blade turns easily. If not your bearings are gone. If it turns easy you may have a bad cap, condenser fan relay or open motor winding. You hear a humming - is the large pipe that goes inside getting cold? That would indicate the compressor is running. Without the condenser fan the head pressure will sky rocket. This makes the little line get hot and the coil will get hot as well. If you have a water sprinkler you can aim it on the condenser coil overnight so you can have AC until the morning. An oscillating sprinkler works best set on park so the coil gets a gentle but constant shower of water. It should keep it cool enough to prevent the head pressure switch from disengaging the compressor.
 

spidey07

No Lifer
Aug 4, 2000
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Outside AC unit, not the blower/inside stuff. You may be onto something with the bad start capacitor (whining/humming). I'll see if the fan turns freely, not with my hands of course, to rule out bearings. It's only 9 years old.
 

MovingTarget

Diamond Member
Jun 22, 2003
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Is this a window unit or a central air system?

Isolate the motor electrically and test for continuity. If it passes, you may have a control board issue. If it fails, then the motor itself is to blame. If it is an older unit, all it may need is a new set of brushes. I'm no technician, but the blower motor may not be something you need an AC guy to fix if you know what you are doing. It isn't like fixing or replacing a compressor.
 

brxndxn

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Apr 3, 2001
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If it's a bad capacitor, you may be able to get the fan started by poking it causing it to start turning.. Don't use your finger unless you hate having your fingers. Then, turn the fan to 'ON' so it just stays running until you can get an AC guy to come and replace the capacitor. The AC will turn off and on when needed.. the fan would just stay on.

 

Rubycon

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Aug 10, 2005
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Originally posted by: brxndxn
If it's a bad capacitor, you may be able to get the fan started by poking it causing it to start turning.. Don't use your finger unless you hate having your fingers. Then, turn the fan to 'ON' so it just stays running until you can get an AC guy to come and replace the capacitor. The AC will turn off and on when needed.. the fan would just stay on.

The outdoor fan relay is controlled by the thermostat so even if the fan inside is set to on it will still cycle. To keep the outdoor fan running requires clipping a jumper wire from the R terminal to the hot side of the coil on the fan relay. If you are not familiar with schematics don't try this - these relays have 240VAC across the LINE terminals! :Q
 

spidey07

No Lifer
Aug 4, 2000
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I'm pretty sure the problem is indeed the AC unit fan (probably bushings, not seized). I can turn the fan blades, using a metal rod, and they move with little resistance. The fan motor itself however is pretty warm to the touch and it's been off a good 30 minutes. Warm as in you can hold your entire palm to it, but you'll want to pull it away after 10 seconds or so.

I'm not willing to risk doing this myself but you guys did point me in the right direction, thanks a ton. I'll be able to give a better description to the repair guy before he comes out.
 

Rubycon

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Aug 10, 2005
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How easy does it turn? If you give the blades a whack if the bearings are good it should spin around one full time and come to rest gently. If it comes to rest fast and not smooth there is too much resistance. This is probably salvageable with an oiling. Look on each end of the motor and you should see tiny plugs usually yellow or black in color. These are the oil filler holes. You can use 3in1 oil in a bind...

Those motors are air over cooled and run quite warm to human hands so a motor that's uncomfortable to touch at a typical 65C running temp is perfectly normal. Now if the motor is not turning at all but getting power it will be quite warm. They are thermally protected with a bimetal protector embedded within the windings. The fact that the motor is warm indicates you have a functioning motor relay/contactor...
 

brxndxn

Diamond Member
Apr 3, 2001
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Originally posted by: Rubycon
Originally posted by: brxndxn
If it's a bad capacitor, you may be able to get the fan started by poking it causing it to start turning.. Don't use your finger unless you hate having your fingers. Then, turn the fan to 'ON' so it just stays running until you can get an AC guy to come and replace the capacitor. The AC will turn off and on when needed.. the fan would just stay on.

The outdoor fan relay is controlled by the thermostat so even if the fan inside is set to on it will still cycle. To keep the outdoor fan running requires clipping a jumper wire from the R terminal to the hot side of the coil on the fan relay. If you are not familiar with schematics don't try this - these relays have 240VAC across the LINE terminals! :Q

Doh.. I misread it and thought he said the air handler fan wasn't running.
 

Engineer

Elite Member
Oct 9, 1999
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I've replaced the outside unit fan motor on two units. They are generally pretty easy to change and usually pretty easy to find (especially if you have a common size and a store like Grainger nearby (or don't mind ordering it)). Never had a problem with the caps though.

The motor should cost less than $100 (maybe below $50 if you can find one that has been rebuilt/rewound).
 

spidey07

No Lifer
Aug 4, 2000
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Originally posted by: Rubycon
How easy does it turn? If you give the blades a whack if the bearings are good it should spin around one full time and come to rest gently. If it comes to rest fast and not smooth there is too much resistance. This is probably salvageable with an oiling. Look on each end of the motor and you should see tiny plugs usually yellow or black in color. These are the oil filler holes. You can use 3in1 oil in a bind...

Those motors are air over cooled and run quite warm to human hands so a motor that's uncomfortable to touch at a typical 65C running temp is perfectly normal. Now if the motor is not turning at all but getting power it will be quite warm. They are thermally protected with a bimetal protector embedded within the windings. The fact that the motor is warm indicates you have a functioning motor relay/contactor...

You my be onto something then. They move, but there is some resistance. Imagine a bicycle wheel with the brakes rubbing slightly. I would not call the fan free moving or gliding.

From your description bearings/lube could be a problem. The resistance is enough to stop the blades quickly - no way am I going to get a full revolution out of them, the motion isn't chunky though. More like very constant resistance.

If anything you guys have given me tons of information to not get taken for a ride.
 

Rubycon

Madame President
Aug 10, 2005
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With the unit running try spinning the blades and see if it takes off. As previously mentioned do NOT use your hands!

A weird thought just crossed my mind...

As I type this my mouse won't even stay still by itself! It's not due to the motion of the ocean but due to the ridiculous bass from "Flight Of The Cosmic Hippo" that's playing. What does this have to do with your stubborn fan? I bet if it were here it would beat it - stat! :laugh:

Double :laugh: for mentioning MOUSE in an A/C thread. Damn stuff is cursed forever I tell you.
 

iGas

Diamond Member
Feb 7, 2009
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Blades is easily spin by hand, indicated that the problem is the capacitor.

 

Platypus

Lifer
Apr 26, 2001
31,046
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Originally posted by: Rubycon
With the unit running try spinning the blades and see if it takes off. As previously mentioned do NOT use your hands!

A weird thought just crossed my mind...

As I type this my mouse won't even stay still by itself! It's not due to the motion of the ocean but due to the ridiculous bass from "Flight Of The Cosmic Hippo" that's playing. What does this have to do with your stubborn fan? I bet if it were here it would beat it - stat! :laugh:

Double :laugh: for mentioning MOUSE in an A/C thread. Damn stuff is cursed forever I tell you.

the hippo has landed
 

Engineer

Elite Member
Oct 9, 1999
39,230
701
126
Originally posted by: Rubycon
With the unit running try spinning the blades and see if it takes off. As previously mentioned do NOT use your hands!

A weird thought just crossed my mind...

As I type this my mouse won't even stay still by itself! It's not due to the motion of the ocean but due to the ridiculous bass from "Flight Of The Cosmic Hippo" that's playing. What does this have to do with your stubborn fan? I bet if it were here it would beat it - stat! :laugh:

Double :laugh: for mentioning MOUSE in an A/C thread. Damn stuff is cursed forever I tell you.

Flight of the Cosmic Hippo 2008...just for you!
 

Rubycon

Madame President
Aug 10, 2005
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Originally posted by: iGas

Blades is easily spin by hand, indicated that the problem is the capacitor.

Cap has probably been going bad for a while and now the bearings stiffening up has added enough resistance to make it lazy. A new cap and shot of oil in bearings should fix it up.



My connection has gone into severe under drive. That will take half an hour to load before it starts playing. :(
 

spidey07

No Lifer
Aug 4, 2000
65,469
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Progress! Turned the AC back on and watched/listened to the outdoor unit start up. After maybe 5-8 seconds after the unit having power to it the screeching started (some kind of compressor protection?). The whining I was hearing is the compressor I'm pretty sure. Still no movement from the fan.

I gave it some very strong turns with a metal skewer, I was essentially trying to "start" the motor. There was much more resistance this time, as in the motor was getting power and in a RUN state. A few more really strong yanks on the fan and it started running. I felt like I was trying to pull start a decent size lawn mower engine.

iGas, sorry, I didn't catch the make/model.

No matter what you guys really helped, thank you. I'm with you RubyCon - probably both. I gave the motor enough to get going but there is still too much resistance.
 

Rubycon

Madame President
Aug 10, 2005
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I'd be willing to bet if you grabbed the fan blades and pulled up and down there's probably a good 1/2" of play there!
 

spidey07

No Lifer
Aug 4, 2000
65,469
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Originally posted by: Rubycon
I'd be willing to bet if you grabbed the fan blades and pulled up and down there's probably a good 1/2" of play there!

They're actually very stable in their rotational plane and the vertical. Blades rotate on the horizontal plane from the cylinder of coils on the vertical plane.

///---motor---///

I'm half tempted to do this myself now. I could just pull the motor and service it! Or just replace it. But the cap is probably elsewhere?
 

xanis

Lifer
Sep 11, 2005
17,571
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Originally posted by: spidey07
Originally posted by: Rubycon
I'd be willing to bet if you grabbed the fan blades and pulled up and down there's probably a good 1/2" of play there!

They're actually very stable in their rotational plane and the vertical. Blades rotate on the horizontal plane from the cylinder of coils on the vertical plane.

///---motor---///

I'm half tempted to do this myself now. I could just pull the motor and service it! Or just replace it. But the cap is probably elsewhere?

I kinda feel like you might want to leave this to a pro. :p
 

Rubycon

Madame President
Aug 10, 2005
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Tug on the shaft to see how much play you have. If it's more than half the diameter of the shaft it's pretty shot. You can oil it up so it spins freely but don't expect this to be a long term repair. Is this a heat pump or AC unit? 9 years of heat pump use is rather tall.
 

xanis

Lifer
Sep 11, 2005
17,571
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0
Originally posted by: Rubycon
Tug on the shaft to see how much play you have. If it's more than half the diameter of the shaft it's pretty shot. You can oil it up so it spins freely but don't expect this to be a long term repair. Is this a heat pump or AC unit? 9 years of heat pump use is rather tall.

must... resist... jokes....