Central Air Conditioning Question – Fan Motor?

problem: when trying to heat the house no warm air blows (only cold) until after we turn the heat up enough for the coils in the furnance (emergency heat) to come on.
we had ac guys come out and they checked everything and replaced the capacitor.
this worked about a day and a half
exact same problem came back. we have not called anyone yet.
additonal info: last night i tried to cool the house, theromstat said it was cooling but no air at all was blowing. i walked out to the unit and i heard buzzing (i heard this when the ac guys were working on getting the heat going) and finally after about 5 minutes, the fan started turning.
i went back inside and cold air was blowing………. the fan outside quit turning again off and on.
the fan blade turns freely (i saw the guy check that so i checked it as well)
when heating: cold air blows until coils in furnace come on (emergency heat), it should at least be warm when you bump it up a few degrees
when cooling: no air blows until the fan outside starts turning which seems to be sporadic.
it seems that maybe instead of a capacitor maybe its another problem
if its the fan motor, i know i can replace that myself because i took it out a few years ago and oiled it no problem.
what does everyone think? i have an ohm tester but if you tell me to use it you will need to tell me exactly what setting to put it on and explain it to me like a 3rd grader :)
thanks in advance for any ideas or help!

  1. Comment by DAN THE AC MAN
    February 20, 2010 @ 7:08 pm

    i’ll assume that the blower motor in the indoor unit [ air handler] always runs when it should…its the outdoor unit fan motor thats the problem??..if so,,likely it needs a new motor..even if the capacitor was bad,likely the motor had run hot for a long time [weeks,months],,the difference between a heat pump in heating season and cooling season is that in cooling season,you will notice a problem soon after it begins due to no cooling,or noticable drop in cooling…in the heat mode,heat pumps arent very good heaters anyway,can be tough to distinguish between a heat pump thats working ok but struggling with the cold outdoor temps, and a heat pump with a problem..therefore that motor is probably bad due to running all that time with a bad capacitor…motors fail in different ways..just because it turns freely with power off doesnt mean the windings are ok…as long as the capacitor is good,a motor that doesnt start up and get to speed quickly after being energized is bad…if it does start up and sound ok at 1st,it might be overheating after running a while…basically,as long as it has power and capacitor is good, [ and correct uf],there is no excuse for is not to be able to run for hours at a time,esp if its cold outside,which should help keep it from overheating…so go ahead and replace the motor if you know how…be sure to get same rpm and = or slightly greater horsepower..also be sure that new capacitor is the correct microfared [uf] for the new motor..if it isnt,then you will have to replace it with correct one for the new motor………dan

  2. Comment by gizmoe
    February 20, 2010 @ 11:21 pm

    Heat pumps are a bit complicated to be able to walk you through a trouble shooting procedure.
    Most companies provide a 30 day warranty on service repairs.
    I would call them back.

  3. Comment by KTB
    February 21, 2010 @ 3:23 am

    Without even knowing what unit you have, your issue is not unknown, nor is it unusual. The Capacitor is certainly not your problem. Your course/heat interchange is. It is called many different things, depending on where you are located, but the unit is always the same.
    This is the device that tells your unit when to operate, and at what capacity. Usually, this issue is caused by a faulty stat (thermostat). Or, and more importantly, someone either adjusted the programmable settings or heat intelligence program (unit specific) to your system.
    My money is on a faulty thermostat. Most programmable units can be corrected without even spending a dime. Write to me, tell me what you currently have (both unit and thermostat wise) and I will present you with a generally simple solution. If, however, after hearing all that you might say, I might come to a conclusion that you may not be happy with, but one that is likely necessary. So please don’t yell at me for being honest.
    BUT, My money is still on the simple and inexpensive solution.

  4. Comment by Brian
    March 11, 2010 @ 10:00 pm

    My blower in the air handler has been running for a week straight (seemingly at a lower speed than when the heat or a/c kicks in.) Even if I turn the whole thing off. (Only disabling it at the breaker stops it). It is not an auto v. manual mode issue. The A/C guy checked a lot of stuff (and replaced a few parts) and finally decided I need a new blower motor. I know very little, but does this make sense? I would suspect the problem is that the motor is being sent electricity constantly and that is the problem. He tested the t-stat and lots of stuff.

  5. Comment by ArnoldArnold
    August 7, 2012 @ 5:11 am


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