More HVAC concerns


Saturday, my HVAC went belly-up.
The outside compressor would not start in the evening. Even the Fan mode would not run by itself. Turn the entire unit off after checking breaker, for ice and dripping from the condensate lines. I left it off all night until early sunrise. Turned it on and the condenser came on, the attic blower came on and in just a few minutes it failed again. Won't start now.
Single story, 1800 sf home, Mojave Desert.. 110 F this week, HOT!
Would this be a start capacitor on the condenser/compressor?
I have a _Comfort Representative_ coming in a few hours. I may replace the entire unit, compressor and furnace/air blower. Go from 10 SEER to what ever?
I'm comfortable replacing the capacitor and have the tools and will be cautious, power off, etc. I don't have a VOM but can get one.
Does this act like a start capacitor? The unit is 13 years of age.
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Oren wrote the following:

I had a similar situation a few weeks ago. It turned out that the thermostat was bad. I though that it was dead batteries, but it did the same with new batteries. Start and then stop. I think that it had something to do with the contacts between the unit and the base. A new thermostat fixed the problem.
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Bill
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wrote:

Good point, I did change batteries last night, and reset the T-stat (digital) to default, but at daylight the HVAC fired up and died right away. The T-stat is acting (working) as it has for years. I won't rule it out though. It does seem to work.
Glad I have a pool right now it is 109 F.
Thanks.
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Jumper the connections on the thermostat that are for cool. If that starts it you have an intermittent contacts on thermostat. WW
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Time to get the VOM and the guy who owns the VOM. Go over everything, looking for power, etc. I don't have enough information to even make a guess.
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Christopher A. Young
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Oren wrote:

Could be - it's cheap enough to try. A capacitor - start or run or combo - should cost, oh, five bucks.
Don't let them talk you into a new compressor. Usually, if it runs at all, it can run forever. Further, I suspect that the replacement of any other part is more economical than a new unit.
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No it doesn't. If it has a start capacitor that would be to start it. It also has a run capacitor. If either of these are bad it more likely won't run at all rather than start and run for a while. If it's starting up and then dying a few minutes later the first thing I would check is the high pressure side. But you need gauges for that. The compressors have a built in thermal over load switch. It sounds like that maybe tripping. Does the outside fan stay on and just the compressor cut off? That would be the overload switch. If the entire outside unit cuts off that may be a safety device of some sort. Some more complex units will shut themselves off if they are not working properly. 13 years is not way too old but it's old enough that I'd think about replacement before a major repair.
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