Any HVAC Gurus Out There?
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Shog9 should have become an HVAC guru by now:). I recently (2 weeks back) had a dead capacitor. The way to find out is if the capacitor is swollen or the size is abnormal. Once it was replaced everything worked fine. But my outside fan was not moving at all. Is it the same with you?
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Roger Wright wrote:
Is there an easy way to check this?
Yes. Do I know what you are talking about? No. :) Believe it or not, there is actually a website called EngineerProject.com[^], don't know if they have a discussion forum for engineering questions.
My .NET Business Application Framework My Home Page My Younger Son & His "PET"
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Roger Wright wrote:
Can anyone tell me whether this is a symptom of a dead capacitor?
Not sure, but it not a huge deal to simply check the microfarads of the capacitor with a multimeter. Should tell you right off the bat if it is good or not.
You may be right I may be crazy -- Billy Joel -- Within you lies the power for good - Use it!
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Shog9 should have become an HVAC guru by now:). I recently (2 weeks back) had a dead capacitor. The way to find out is if the capacitor is swollen or the size is abnormal. Once it was replaced everything worked fine. But my outside fan was not moving at all. Is it the same with you?
Yes, the fan stopped. But it started up again once I cooled the system off with water.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Yes, the fan stopped. But it started up again once I cooled the system off with water.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Yes, the fan stopped. But it started up again once I cooled the system off with water.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
So you have to cool the fan, instead of the other way around? :)
Luc Pattyn [Forum Guidelines] [My Articles]
DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
You need to go low-tech and get a swamp cooler. I thought they were standard equipment out in the desert.
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Roger Wright wrote:
Can anyone tell me whether this is a symptom of a dead capacitor?
Not sure, but it not a huge deal to simply check the microfarads of the capacitor with a multimeter. Should tell you right off the bat if it is good or not.
You may be right I may be crazy -- Billy Joel -- Within you lies the power for good - Use it!
Not really. It depends on the fault. A leaky capacitor and a good one can look the same, because the DMM can't put out much current. In a perfect world, the resistance would look low for a few moments, then rise to infinity. In the real world they tend to waver a lot and never get to a high level of resistance. An open capacitor gives an open indication right away, but that's an odd way for electrolytics to fail. Even film types rarely open.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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You need to go low-tech and get a swamp cooler. I thought they were standard equipment out in the desert.
They are when the humidity is low enough for them to work, but that season is over. From now until Fall the dewpoint will be too high for them to work.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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They are when the humidity is low enough for them to work, but that season is over. From now until Fall the dewpoint will be too high for them to work.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Humid and 120. You need to get that thing fixed fast. I used to live a bit southwest of Death Valley. Evaporator was all you needed there.
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Unless it's inacessible, changing the cap is going to be inexpensve both in $ and time, so I'd just do it anyway.
Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)
Why are you using VB6? Do you hate yourself? (Christian Graus) -
Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Can you not measure the SCALAR voltages with your DMM (Supply voltage, Capacitor voltage, Motor voltage) and infer - or at least get a good idea of - the phase angle from that? It might also be worth looking for the stupid fault - is everything free running or has something expanded in the heat and jammed?
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Got a question... This weekend, when the temp hit 121°F, my a/c unit quit. The condenser fan motor stopped turning, the refrigerant vaporized, and the compressor was working its little iron heart out trying to work it all out. Without success, I might add. I shut down the system for an hour and hosed off the condenser coils to liquify the refrigerant, and it started working again. I've replaced this motor a few times over the years, a 10 minute surgery that the a/c guy charges $270 to do, and the motors used to cost $50. Now they've gone up to $180, so I'm not so quick to replace this one. It uses a 5μF run capacitor, and I've just read that the capacitor should be replaced every time the motor is changed out; I've never done that. Can anyone tell me whether this is a symptom of a dead capacitor? I really don't want to get out the oscilloscope and check the phase shift between the main and auxillary windings of the motor in this heat, but the a/c guys I've talked to are all idiots. They suggest checking continuity across the cap with a DMM. That's useless unless the thing has failed open, a rather rare failure mode for capacitors. Electrolytics usually fail shorted because of punch-throughs of the dielectric between foil layers, or loss of Q or capacity through electrolyte dehydration. Is there an easy way to check this?
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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So you have to cool the fan, instead of the other way around? :)
Luc Pattyn [Forum Guidelines] [My Articles]
DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.
Luc Pattyn wrote:
So you have to cool the fan, instead of the other way around?
...only in Soviet Russia...
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Yes; I have automatic updates enabled. And I did reboot. Twice.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Unless it's inacessible, changing the cap is going to be inexpensve both in $ and time, so I'd just do it anyway.
Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)
Why are you using VB6? Do you hate yourself? (Christian Graus)It certainly won't hurt. :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Can you not measure the SCALAR voltages with your DMM (Supply voltage, Capacitor voltage, Motor voltage) and infer - or at least get a good idea of - the phase angle from that? It might also be worth looking for the stupid fault - is everything free running or has something expanded in the heat and jammed?
Everything spins freely, but since the failure is intermittent (I only notice it when the sound is "wrong") I can't tell if the fan stops, or fails to start. If it stops, that would indicate that the built-in thermal protection of the motor is kicking in, and increase the likelihood that the motor is bad. If it fails to start I'd be more inclined to suspect the capacitor.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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Pixa wrote:
Is it plugged in?
I can't tell. It's dark back there because the power is out. ;P
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
