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Discussion Starter · #1 · (Edited)
Bought this house last June. When we moved in, one of the capacitors located in the central air's outside unit was bad - called in an HVAC tech who replaced it and added a hard-charging kit. It ran perfectly after that through the rest of the summer.

We started using it again in April and it was working fine until just last week. We went away on a week-long vacation and on my way out the door I set the temp to 76 degrees, since no one would be home no sense in cooling it too much. When we got back I dropped it back down to 72 and it worked fine, but then, at numerous times throughout the day since, what happens is I'll notice the air is not blowing as cold (but it is still blowing), will look at the thermostat and it will be reading the inside temp at 75 degrees even though we have it set to 'hold' at 72 degrees during the day.

This happens for a short while and then it starts working as normal again, brings the temp in the house down to 72 (or whatever we set it to be) and then after a while it cuts out again for a while.

This has been happening for the past 2 weeks. It's been fairly comfortable - it never gets too hot. But I know something's wrong. Unfortunately, some other financial hits have come up during these two weeks (dog died, after numerous high-cost emergency vet bills, and my dryer just broke down...it's been a tough week : (

The problem, I believe, is in the outside unit. When I go out there sometimes the fan is blowing and it is operating as would be expected. But other times it is very loud, with a slight hiss to the sound, and the fan is not turning at all. The coil is not blocked or frozen. The unit is just louder than normal, and no fan blowing.

Before I call someone, I was hoping someone here might be able to give some advice as to what the problem could be.

One last thing - when this first started happening I *hoped* it was just the thermostat, so I bought a new one (same type honeywell) and replaced the old one with it. But it did not solve the problem.

*** additional info:
After posting this I noticed it's off again, with somewhat cold air coming out of the registers but not nearly as cold as normal, so I went out and checked the outside unit and the fan is not turning, but there is just a not very loud 'hum' sound coming from the outside unit. I have some electrical/electronics experience but no HVAC experience so forgive me for guessing, but it seems to my unprofessional eye that perhaps the motor is bad and it is overheating and there may be some type of protection circuitry in it that cuts it off until it cools down, then restarts it when it is cool enough, and the cycle continues? Just a guess.
 

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if the compressor is running from the stat the condenser fan should be also....not to deep on controls they always both run.....next time it isn't running shut the disconnnect outside...touch the casing of the condenser motor if it is tooo hot:censored: it need to be changesd probably triping internal overload from heat spin with no power on the condenser...both ways should free spin...brakes hard bearings took a hit during the winter or rain sitting there....get back for where to get motor if your in a $$ crunch at leastthe labor is free:wink:
 

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Either the capacitor is weak on the fan side or the fan motor needs replaced. Turn the unit off until it's fixed or you will be buying a new compressor. That internal pressure relief that you hear hissing can not take too much abuse.
 

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Discussion Starter · #4 ·
Thanks guys. I just got back from visiting a relative and it appears the outside unit is no longer working at all now. I just shut off the central air and was thinking I'd turn it back on tomorrow morning and see if anything happens, and then cut power and take a look. With the holiday weekend there's no way that I can get a tech out anytime soon so it won't hurt for me to take a look myself for now. My brother is a licensed HVAC tech but he does not work in that field (he's an electrician). I gave him a call to see if he can make the drive out to take a look soon. I'll reply back to this thread with what I/we find.
 

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Discussion Starter · #5 ·
So I woke up this morning and figured I'd take a look at the AC outside unit to see why it wouldn't run. I started by turning on the thermostat to cool, setting it to hold at 70 degrees (house temp was 76 at the time), and then I immediately walked outside to the side of the house where the outside unit is. To my surprise, it was/is running, and working normally.

I have no illusions that it will continue to work fine. But for now, my goal is to get the house temp down to 70 or less, in order to keep the downstairs somewhat cool during what will likely be a pretty hot next 2 days. Perhaps I got lucky by shutting it down for the night - perhaps it just 'reset' something? I'll report back when it stops working (I have a feeling it will be once it gets hotter outside today and it overheats). Once it does stop working properly, my plan is to cut the power and pull the cover and take a look at the electrical area to see if anything is obviously defective. Until then, it's working, and so now it's off to figure out why my dryer is producing no heat all of a sudden....been a rough week : (
 

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Discussion Starter · #6 ·
Update: it's been running fine every since yesterday morning. I set it to 69 degrees in the AM, in order to get the house as cool as possible before I assumed it would stop working, but it kept going. Temp was hot yesterday. I now set it back to our normal 72 degrees and it's staying steady. Perhaps shutting it off for the night reset something? No idea. But it's working....for now : )
 

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Discussion Starter · #7 ·
Final Update: so it worked fine until about 7pm that night when I noticed it was no longer pushing out cool air. Inside unit was still running but outside unit fan not running. Restarting resulted in compressor firing up but fan not, so I got a new fan motor and replaced that, along with the run capacitor, and it's now been running great for the past 2 days. Fan motor cost me $140 for a direct replacement (I have a relative who works for a company that has steep discounts through grainger and other parts suppliers, so I got almost a 50% discount over list).

Glad it's fixed : )
 
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