condenser fan failure? or something else?

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Old 06-17-19, 07:14 AM
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condenser fan failure? or something else?

hi all!

when i 1st turn on my home a/c system, everything kicks on - except the condenser fan outside. you can hear the compressor humming away. but if i give the fan a nudge w/a stick, it starts turning, then runs, and everything's hunky dory, w/the a/c working fine.

the problem is, when it cycles off, then back on. because, then, if you're not there to baby-sit it, the condenser fan will not start; which means the compressor will just shut off, as the system overheats, and then stops. inside, the interior fan is running, and you don't notice a problem until it starts getting warm. then, if you shut the system off and let it cool down for a while, you can get it to run again, as long as you run outside to push-start the condenser fan.

my question - is the fan shot, and replacing it going to fix the a/c, or is there something else causing the fan not to start on its own?

thanks!

doug s.
 
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Old 06-17-19, 08:42 AM
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Check the run cap or try replacing it and see if that solves the problem.
 
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Old 06-17-19, 10:12 AM
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Test the capacitor with your meter.
 
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Old 06-17-19, 10:14 AM
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Your existing capacitor is probably two capacitors in one container and called a dual capacitor. Read the side of the capacitor and get the existing MFD numbers, then go buy a new capacitor. It will be located behind the access panel on your outdoor condensing unit.
 
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Old 06-17-19, 11:35 AM
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hi vs martin!

you said:
"Check the run cap or try replacing it and see if that solves the problem."

thanks for the reply. ok, i did some research; why would you think it's the run cap and not the start cap? since it runs, but won't start, w/o a push on the blades. i am not trying to be a smart a$$, i simply don't know enough about it.

thanks again!

doug s.
 

Last edited by doug s.; 06-17-19 at 11:45 AM. Reason: identify the post i am responding to
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Old 06-17-19, 11:40 AM
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The fan motor will only have one capacitor
 
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Old 06-17-19, 11:50 AM
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Hi roughneck77!

You said:
"Test the capacitor with your meter."

i'm familiar w/testing resistors, but capacitors, not so much. what, exactly am i wanting to test, and what setting on my multimeter should i be using? i bought a cap tester quite a while ago, but have never used it.

thanks again!

doug s.
 
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Old 06-17-19, 11:54 AM
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You’ll need a meter capable of measuring capacitance. Not all will.
 
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Old 06-17-19, 11:57 AM
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You need to check the capacitor for rated capacitance. It should be in the 5-10mfd range. If you don't have a capacitance setting on the meter try the capacitor tester. If that doesn't work buy a replacement and try it.
 
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Old 06-17-19, 03:00 PM
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hi roughneck77,

you said:
"The fan motor will only have one capacitor"

ok, i just checked, (now that i'm home), and as i suspected, there's two capacitors. maybe only one is the start/run cap?

[img]file:///C:/Users/doug%20sedon/Documents/ac%20cap%201%20up%20close.png[/img][img]file:///C:/Users/doug%20sedon/Documents/ac%20cap%201%20up%20close.png[/img]
thanks all, for your assistance!

doug s.
 
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Old 06-17-19, 03:49 PM
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The run capacitor is actually a duel cap in your photo.
 
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Old 06-17-19, 04:28 PM
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You will want to test the GE capacitor (on the left). Your reading should be 7.5 mfd +/-.5. Test between the common and fan terminals. When testing allow the leads to make contact with the terminals for a few seconds to get an accurate reading.

Visually inspecting the GE cap does the top look bulged at all? If yes, or you are unable to test the capacitor look like this is a replacement.

https://www.amazon.com/Genteq-Round-.../dp/B00BY9IH4W

Note : To prevent an electric shock pull the DC to the condenser unit prior to doing any tests and good practice to short the terminals on the capacitor before removing it.
 
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Old 06-17-19, 04:32 PM
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they're cheap, both delivered in 2 days, for $35. so i am going to replace both.

another question - the board has a light that blinks 6 times, then stops; then repeats. the legend says it's the compressor ptc's out of limits i guess the a/c compressor has to cool down before it will run again? it has not always started after the normal 5 minute delay is over. i didn't see the light until i pulled off the covers to check caps.

so, my question is this - why is the light still blinking, when the unit is turned off, and the fuses inside the mondo outside box have been pulled? the light still blinks, and there's juice still on some of the wires. (both caps have been bled.)

thanks,

doug s.
 
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Old 06-17-19, 05:38 PM
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there's juice still on some of the wires
Which wires? Did you measure voltage? Is this a package unit? Post pic or # of the board and the pros will be able to answer better.
 
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Old 06-17-19, 06:42 PM
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tumble, you said:
"Which wires? Did you measure voltage? Is this a package unit? Post pic or # of the board and the pros will be able to answer better."

no, i did not measure. i just got a shock when i went to reconnect a pressure switch that a tech bypassed last year, doing troubleshooting on a different area. i replaced the contactors last year, which had failed.

the unit is an old bryant dual stage unit. - model 598a
https://dms.hvacpartners.com/docs/10...I598A-36-7.pdf

but now it seems the unit is permanently off - the compressor's ptc out of limits switch will now not return to its limits, even when the compressor has cooled off. so i am not sure the unit will run when i install the new capacitors. and yes, the ge cap is quite bulged at the top, so i am sure it's bad. is it possible to replace the ptc sensor in a compressor, or does the compressor have to be replaced?

doug s.
 

Last edited by doug s.; 06-17-19 at 07:03 PM. Reason: typo; more unit info
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Old 06-17-19, 06:49 PM
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The pressure switch would have had 24vAc on it. You may have felt a tingle but it would not hurt you. That 24v comes from the thermostat via the yellow (Y) wire.

The thermal overload is deep inside the compressor and cannot be replaced.
The compressor will stay hot for many hours once the thermal has been tripped.
 
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Old 06-17-19, 07:09 PM
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PJmax, you said:
The pressure switch would have had 24vAc on it. You may have felt a tingle but it would not hurt you. That 24v comes from the thermostat via the yellow (Y) wire.

The thermal overload is deep inside the compressor and cannot be replaced.
The compressor will stay hot for many hours once the thermal has been tripped.


thanks; i will try again tomorrow.

curious, where the 24v is coming from (tho it felt like more than that; i have felt low-voltage system shocks before) or where is any voltage coming from, if all the power is turned off? and, is the 6-blink light powered by the ptc in the compressor? i thought it would turn off; it was blinking even when i disconnected the leads from the ptc to the board.

doug s.
 
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Old 06-17-19, 07:25 PM
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Typically in a heat pump system....... the 24v comes from the transformer inside of the air handler.
There would be an always live (R) to run the board, a compressor lead (Y) and a reversing valve (O).
 
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Old 06-17-19, 07:42 PM
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thanks, pete; i just now turned off the ahu as well. tho it's gas, not electric. there was a separate breaker for it in my inside electrical panel... we'll see what's up at the condenser tomorrow.

thanks again,

doug s.
 
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Old 06-17-19, 08:55 PM
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So you have a gas furnace with a split A/C system.
That means only one 24v wire (Y) and one C wire to the condenser.
 
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Old 06-18-19, 02:57 PM
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hi all,

well, when i came home today to check everything out, w/the ahu and the a/c condenser breakers flipped back on, the panel lights at the condenser board were continually flashing - indicating board failure. i was not happy. but, i decided to try starting it up anyway; the compressor kicked on; again the fan needed a nudge and started running. now, everything is cooling again. and now, the board flashes twice, pauses, twice pauses, etc - indicating hi-speed fan position.

when it cools down the house and shuts off, i suspect i will have to push-start the fan again, for it to run. but the new start/run capacitor arrives tomorrow; hopefully, the unit will start all by itself w/the new part. we'll see.

thanks,

doug s.
 
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Old 06-19-19, 03:02 PM
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hi all,

so, the new cap showed up today; took ~5 minutes to install. (even the bleeder resister was soldered to tabs, so it was all plug-n-play.) now, the condenser fan starts right up. and, its low speed works, as well as the high speed. can't remember the last time that happened!

and yes, the old cap was bulging quite badly:

so, $12.96, and i am back in business!

thanks all!!!

doug s.
 
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Old 06-19-19, 07:21 PM
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Good job. Name:  thumb.jpg
Views: 43
Size:  1.6 KB Thanks for letting us know how you made out.
 

Last edited by PJmax; 06-19-19 at 07:37 PM.
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Old 06-24-19, 05:50 AM
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doityourself is a great resource. now, i will post in the plumbing section so someone can help me figure out why my water heater only intermittently give hot water at the tap.

thanks again to everyone, for the help!

doug s.
 
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