Heat Pump Exterior Fan and noise help


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Old 02-20-07, 08:10 PM
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Heat Pump Exterior Fan and noise help

I've been here for about a year in this house with a heat pump. Some problems in the past, but the tech has come out and repaired it. My quetion is should the exterior unit make a loud electrical noise while it is on? I've seen the fan running outside during the summer and thought that it ran in the winter as well, but it does not run right now. It makes a loud buzz or hum while it is on, like a lot of current is going through it. I don't want to call the tech and pay if nothing is wrong. Heat is working, but sometimes it will blow ice cold for a few minutes then get warmer. The electric bill doubled this month, but it is very cold, 30 degrees colder than normal. I'm afraid its going to blow.
 
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Old 02-20-07, 11:10 PM
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Yes and no. On some units the fan dont run in defrost. So what you have Id say call a tech. You can put it over to AC and see if the fan runs. If not give it a push with a small stick the way it turns. if it runs then you only need a capacitor for it . If not can be the motor then on to the defrost board. For sure get it fixed. High bill Id have the freon checked also. is the air filter clean ? It helps on the bill???????
 
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Old 02-21-07, 06:16 AM
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At first I thought it needed a push, but it was on heat still, i pushed it and it spins fine, i thought maybe if the motor was fried it would not turn. I kicked the ac on and i didn't hear it, but does it always turn on with the ac? Is there a way I can just test the motor on the fan out there. I'm pretty good and fixing things, but need some sort of step by step on this one. the local hvac place wasn't that helpful. they admitted being new to heatpumps and we aren't from the area. The filter is clean, just replaced it. The motor on the inside unit fried last year due to not being clean (before we moved in).
 
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Old 02-21-07, 06:44 AM
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Okay, more to this. Today its not as cold as it has been. The loud buzz I heard briefly and now I can hear a small compressor like noise. I walked over to it and the fan isn't running, but you can hear it running, but its not noisey like it usually is. The air is warm, not ice cold like when it is usually not buzzing.
 
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Old 02-21-07, 09:08 AM
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Quote " i pushed it and it spins fine, i thought maybe if the motor was fried it would not turn".
I think Ed was correct you probably just need to replace the Condensor fan capacitor. Most residential heat pumps use a dual capacitor which runs the compressor and fan will be a can looking thing about the size of a soup can with wires running to it. NOTE/CAUTION/WARNING capacitors store electrical energy after the power source has been shutdown. If you touch the terminals and the capacitor has not been discharged you could recieve a nasty shock. The high electric bill makes sense, if the outside unit fan is not operating the outside coils cannot efficiently get rid of the cold (pull enough air thru the coils to keep them from freezing) and will constantly freeze up putting the unit into defrost mode to often plus making the backup heat kick in.
 
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Old 02-21-07, 03:28 PM
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So if I look for the capacitor, can i shut down the power, let it sit then change it out? Will it have a part number or something on it? Any way to test this out before I change it? Sounds like a cheap part. My normal therm usage is 1700, 5400 last month. I just can't see it being that much difference when in the summer it runs all day for AC and doesn't soak up that much elec.
 
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Old 02-21-07, 05:03 PM
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You could read this:

http://toad.net/~jsmeenen/capacitor.html
 
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Old 02-21-07, 05:30 PM
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heres another question.


sounds like it is probablythe cap. can i run a jumper to make sure the fan fires up? if it does, how much and where can i get the capacitor? i here the buzz right now, but it has been going on and off all day opposed to on all day when it was 0 out.

thanks for the help, u guys have been more helpful then the hvac co out here
 
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Old 02-21-07, 05:39 PM
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Turn the outside unit off till you get the fan fixed .
 
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Old 02-21-07, 05:44 PM
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I'll have no heat?!
 
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Old 02-21-07, 05:47 PM
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Turn the tstat to EME or AUX and you will have electric heat.
 
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Old 02-21-07, 05:54 PM
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I was wrong, my fan is stuck

Whats that due to my bill?? So i was out there just now looking for the capacitor. The loud buzz started and my fan tried to turn on. It moved an inch then stopped, an inch then stopped. I'm going to try to give it a good spin to see if it is just stuck. This is just a simple swap out to a new fan motor right? I'm so mad that I heard this and never had it fixed now. what awasted of money on elec...
 
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Old 02-21-07, 05:55 PM
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Also, if i flip it to AUX, will it stay hot the entire time or just when it needs to warm the house? I can't swing another month of 5412 KWH
 
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Old 02-21-07, 06:11 PM
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That will only come on when you need heat in the home . It works off the tstat just as the heatpump does
 
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Old 02-21-07, 06:27 PM
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Okay, i can do something else too, can I unplug the wires to the fan with no problems to keep the fan from getting full power and not spinning? I grabbed the numbers off it
FPN Stock 3729
S4070SV

Its a GE. Is it really just plug in? Looks like a few bolts.
 
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Old 02-21-07, 07:07 PM
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How cold is it where you are right now? In maybe 15 minutes you could test the motor and the bearings. Test the bearings first as this is the quickest thing to do. With a push of the blades(with this unit off!) will it keep freely rotating around and round and round for many many turns, like it should.

If you can't get to where wires to fan might just plug in at a contactor or some other termination, you could snip the run and neutral wires and nut them back together. Test current in the wire that feeds the motor to make sure you are getting full line voltage. Then do a continuity test between your run wire and the neutral wire. Then test for a full short to motor casing(something you don't want...and would indicate the motor is junk, for sure, if this test is done with the wires diconnected from the motor) by putting ohm test leads between run wire and case. (You should have no continuity for this last test).

IF the motor checks out, it then would almost have to be the capacitor.

But the symptom you gave is also indicitive of a bad motor. A bad motor winding can cause the motor to hum and try to spin a blade like for one inch and then stop and hum. And if you try to push the blade while it is on and humming...sometimes it will spin for a short bit, but then stop again and seem to be magnetically glued in a position and won't let you freely spin the motor blade unless you turn off the power. But as soon as you turn the power on, the blade becomes 'frozen' again as if magnetically attracted to some spot. I have changed out quite a few burned out motors that behave this way.
 
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Old 02-21-07, 07:29 PM
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I just pulled it off and put it back on, i tried with the two wires disconnected and it sounded like it was louder so I realized i was only cutting part of the power, i reconnected the wires on the side, small wires, and i did them backwards and the motor reversed and RAN FINE!? So should I leave it in reverse mode until I get a new motor to install? I'm going back out there to try it again in the direction it was in, but why would it run in reverse?! common sense would tell me since it is reversable it will work fine until fixed and just send air the wrong way. Please let me know what you guys think. Its getting late and its cold as hell in here right now with everything off!
 
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Old 02-21-07, 07:47 PM
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Nevermind, its fried in reverse now too. I set it up in reverse, put two bolts in plugged it in and same thing as forward now. I should have just left it alone the first time I had it spinning in reverse! Guess I'll need a motor its a GE 3729 if anyone knows a cheap place in Rochester, NY?
 
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Old 02-21-07, 10:27 PM
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If you can buy from them Johnstone Supply and Grainger

Make sure the same HP , RPM and that it turns the same way CW or CCW
 
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Old 02-22-07, 07:05 AM
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called grainger, they won't sell to me. I gave in and called my HVAC Co. They are going to give me a price over the phone.
 
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Old 02-22-07, 02:47 PM
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Fixed

Tried replacing just the capacitor, no luck, went back and found and AOS motor the same specs as the GE for $99. PUt it in and it works perfect, quieter than ever! It should be blowing the air up through the grate right?
The HVAC People I called this am never even bothered to call me back to fix my heat. Glad I found this forum. Thanks!
 
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Old 02-22-07, 05:20 PM
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Glad you got it. Yes the air should blow up.
 
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Old 02-22-07, 05:23 PM
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Thanks to everyone!

Thanks everyone who responded, I think I saved a few hundred bucks today. I bookmarked this site with the hopes that I'll never need it again, but that is unlikely.
 
 

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