Need Help Diagnosing Air Handler Noise/Problem


Old 09-22-14, 11:41 PM
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Need Help Diagnosing Air Handler Noise/Problem

I'm having a problem diagnosing a situation with my Air handler inside my condo. Its a PF4M NA025 Payne model and whenever the AC turns on it seems like the blowing speed is fine for a minute or two, then slows down and I can hear a noise coming from the air handler. almost like a vibrating/shaky/humming noise. The air blowing out when slowing down is still cold, but nowhere near the usual blowing speed, barely a light breeze. I'm wondering if this is common or if anyone has any ideas on where I should begin to look to find a problem. Thanks
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Old 09-23-14, 07:17 AM
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I suggest you inspect the air filter to make sure it is clean, the return air ducts are not blocked and all vents are open. The type of blower motor you have are sensitive to any restriction of air flow. Have you recently changed the type of air filter you are using? You can remove the air filter and see if that abates the vibration and noise issues.
Old 09-23-14, 07:38 AM
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Not the air filter. It's definitely something internal inside the air handler in the closet. Some more background info: The unit is only 3 or 4 years old. The condo say vacant when it was built in 2010-2011 for about a year. Lots of electrical and plumbing problems around the 16 unit condo (company that bid for the job bid extremely lower than the other companies and their work certainly shows for it). The AC unit has not had any problems, but here in west central coast florida, it has been raining a lot lately. Ive noticed several months ago the outside ac unit had a loose bolt and was rattling/shaking around, so I tightened it and it seemed to fix it, i believe unrelated. There has been some visible mold, moisture in the closet with the inside unit, possibly related. i removed all air filters to examine if coils needed to be cleaned and noticed the coils (the ones on the inside unit that resemble that of a car's radiator) were extremely wet when I tried to vacuum the little dust that was around them. Not sure if they should be that wet, but the drainage seems to be functioning fine.

The main description/audible problem im seeing is that when the noise begins to come from the inside ac unit, resembling an echoing almost metal-to-metal sound, like something spinning but with friction from metal not being lubed?, thats when the vents blowing speed practically halts. then it may sound like the ac kicks on again and it starts blowing again for a second until the noise returns and the blowing speed is reduced to barely a light breeze.

ANY advice is greatly appreciated, thanks everyone!

I have the unit turned off now, and will try to keep it off all day to see if it works after resting for a while. There is lots of overcast and looks like rain coming, so its only about 80 inside.

Thanks again everyone!
Old 09-23-14, 08:22 AM
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When the A/C system is in use the inside coil will be wet and especially right after the system shuts down. It sounds like you may have a defective blower motor in your air handler. The unit should have a removable cover where you can access the blower and motor. With power turned off - check for binding motor.
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