Strance A/C problem

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I'm having a strange problem with the A/C (a heat pump). One night near the end of last summer we had some lightning. The next day our upstairs A/C started blowing hot air so I called the A/C repair. They topped off the coolant, replaced the capacitor. They also said that the thermostat was calling for the heat strips, so the thermostat was replaced. The A/C was working. A day or two later the A/C was not blowing cool air. I determined that the compressor was running but the fan compressor was not turning. But the problem was intermittent. Anyhow they came back out and replaced the fan motor. It worked for about two weeks, but it was always noisier than the old one they took out. Then it quit working some of the time, but the problem was again intermittent. I had a hard time getting the fan to quit turning when they were out here, but finally it happened. They said that the motor they had put in was defective, and they put in another one. This motor was quieter than the one they replaced. This was near the end of summer, so soon we didn't need cooling anymore. They made a total of five trips.
Skip to about two weeks ago, once again cooling is needed. It was working, but I heard it make a loud noise, and the compressor fan stopped turning again. (One of the copper tubes also gets pretty hot when this happens.) This was in the middle of the afternoon. I thought that maybe the fan had gotten too hot or something. I turned it off and then tried it about six hours later, at night. The fan would not start turning. I waited until the night of the next day and tried it again - the fan would not start. Then it was cool for about a week and cooling was not needed. At this point I thought that it was never going to come on and I was going to call the repairmen again, but I was waiting for hot weather again. But then my daughter turned it on a few days ago and it has been working ever since.
That is a shortened version of the story. I also tried some experiments. It is on a setback thermostat, which was set to allow the temp to go to 81 during the day and then cool down to 79 at 5PM. I thought that it may be trying to do too much work in the process and overheating. I tried keeping it set on 79 to reduce the strain at 5PM. Sometimes it would work, others it would quit. I tried keeping it on 77 with the same results - sometimes the fan ran, sometimes it did not.
What can be the cause of this behavior? Keep in mind that we had some lightning just before the problem started so it may be electrical, but the thermostat has been replaced and the motor has been replaced twice.
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Makes me wonder if there is a circuit board in there some where.
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On Tue, 26 May 2009 22:24:32 -0400, "Stormin Mormon"

I don't know. It is about 9 years old.
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On Tue, 26 May 2009 22:24:32 -0400, "Stormin Mormon"

When the compressor fan is running and stops (while the compressor is still running), it makes a big noise, as if something mechanical is wrong. Also, if it won't start, it makes a noise (not as large).
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On Tue 26 May 2009 06:55:55p, Jud McCranie told us...

I can't address lightning and a/c or heat pump, but after we had a lightning strike, most of our electronic devices were either fried or damaged. This, even with whole house and individual surge suppressors. Even after costly repairs, various problems continued. We finally just replaced everything, as repairs were overrunning the cost of new equipment.
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On Wed, 27 May 2009 02:46:58 GMT, Wayne Boatwright

That's not what I wanted to hear :-( I don't know that we did get hit by lightening - nothing else was affected. But there was lightning in the area, and the thermostat was acting strangely.
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On Tue 26 May 2009 08:21:44p, Jud McCranie told us...

I sympathize, Jud, but it may prove to be an unfortunate and unpleasant reality. If it were me I would monitor the accumulated expenses and, at the same time, price out a new replacement unit.
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Jud McCranie wrote:

Are you sure they used the right (and a good quality) capacitor?
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No, I have no way of knowing that. Could that cause these symptoms?
They did take all of the data about the model of the unit, so I assume they put in the right one. But they did use a low-quality motor, so they may have done the same with the capacitor.
Seems like just about every time I've have A/C repair through the years (here and elsewhere), they replace the capacitor.
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snipped-for-privacy@comcast.net (Jud McCranie) writes:
| I'm having a strange problem with the A/C (a heat pump). One night | near the end of last summer we had some lightning. The next day our | upstairs A/C started blowing hot air so I called the A/C repair. They | topped off the coolant, replaced the capacitor. They also said that | the thermostat was calling for the heat strips, so the thermostat was | replaced. The A/C was working. A day or two later the A/C was not | blowing cool air. I determined that the compressor was running but | the fan compressor was not turning. But the problem was intermittent. | Anyhow they came back out and replaced the fan motor. It worked for | about two weeks, but it was always noisier than the old one they took | out. Then it quit working some of the time, but the problem was again | intermittent. I had a hard time getting the fan to quit turning when | they were out here, but finally it happened. They said that the motor | they had put in was defective, and they put in another one. This | motor was quieter than the one they replaced. This was near the end | of summer, so soon we didn't need cooling anymore. They made a total | of five trips. | | Skip to about two weeks ago, once again cooling is needed. It was | working, but I heard it make a loud noise, and the compressor fan | stopped turning again.
It seems unlikely that you had three bad fan motors. Given that it is a heat pump, the obvious guess is that a damaged defrost controller is erroneously entering defrost mode. On my heat pump defrost mode turns off the outside fan and turns on the secondary heat (heat strips in your case). You might want to check whether your heat pump is (was?) wired to be able to energize the heat strips during a defrost cycle.
I have one of the auxiliary indicator LEDs on my thermostat connected to the secondary heat line. The thermostat already has an LED to indicate that it is calling for secondary heat and this LED is conveniently _not_ turned on when something else (in this case the heat pump's defrost control) drives the secondary heat line. The combination of the two LEDs makes it easy to notice when something funny is going on.
                Dan Lanciani                 ddl@danlan.*com
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On 27 May 2009 06:02:30 GMT, ddl@danlan.*com (Dan Lanciani) wrote:

I haven't heard of defrost mode before, but that is making sense. The repairman said that the old thermostat (now replaced) was calling for the heat strips. This A/C is for a small upstairs, and when it is not working, at the bottom of the stairwell you can feel warm air coming down. So it may still be turning on the heat strips.
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wrote:

Lightning, it destroyed my AC and house electronics, call your insurance co and see what they say even though you are late. Lightning strikes are recorded, it can be proven or disproven it happened on that day if data is still stored. I would be suprised if the data is not still stored somewhere, insurance companies use it. Get a pro out it could be an expensive fix.
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On Wed, 27 May 2009 04:20:03 -0700 (PDT), ransley

We have a high deductibles.
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wrote:

It could cost more than you ever imagined, a new unit.
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On Wed, 27 May 2009 17:19:11 -0700 (PDT), ransley

Yes, A whole new unit would cost more than the deducible.
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On Tue, 26 May 2009 21:55:55 -0400, Jud McCranie

Jud, It could be lots of things. But first and foremost, why dont you find a company that doesnt just change parts at your expense? Its really not rocket science. You just need to find someone good at what they do. You've been using parts changers. That gets expensive. Ask your neighbors, co-workers, clubs, groups who they use and who they would recommend. Bubba
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wrote:

Bubba's advice is right on. There is no point in replacing an entire unit just because the defective part has not been determined. Intermittent problems are more difficult, but not impossible for a good troubleshooter.
Don Young
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wrote:

These were recommended to me, but there is one NATE certified place.
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On Tue, 26 May 2009 21:55:55 -0400, Jud McCranie

A few more days have gone by, and it seemed to be working until a few minutes ago I noticed a strange smell coming down the stairwell (which has been an indicator before). The compressor fan was turning but the thermostat was set to 79 and it was 81, and had been running a while. I suspect that the heat strips are on, which makes the smell.
I don't really need the heat strips upstairs anyway. Is this something the layman can disconnect?
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snipped-for-privacy@comcast.net (Jud McCranie) writes: | On Tue, 26 May 2009 21:55:55 -0400, Jud McCranie
| | >I'm having a strange problem with the A/C (a heat pump). ... | | A few more days have gone by, and it seemed to be working until a few | minutes ago I noticed a strange smell coming down the stairwell (which | has been an indicator before). The compressor fan was turning but the | thermostat was set to 79 and it was 81, and had been running a while. | I suspect that the heat strips are on, which makes the smell. | | I don't really need the heat strips upstairs anyway. Is this | something the layman can disconnect?
Probably, but I'd still be concerned about what is turning them on. If it is a damaged defrost control as I previously suggested it might return to its behavior of shutting off the outside fan. Maybe it had done that and you didn't notice the smell until after the cycle was complete and the fan turned back on.
                Dan Lanciani                 ddl@danlan.*com
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