Air Conditioning - Whistling noise in AC

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timmyg123
09-13-05, 07:33 PM
Have had the system for 4 years. Almost everytime it starts up,
I hear a loud and very high frequency whistling noise for 15-20 seconds
somewhere near the compressor just inside the wall.

HVAC guy could never figure out the problem years ago and it's
time to try again.

Is this common? Anyone know possible causes?

lenny56769
09-13-05, 07:42 PM
if its comeing from wall could it be a air leak in your duct system most duct in homes are not sealed and air can blow out the drives that hold the two pieces together making a Whistling . if this is the case get some duct seal and paint it out .
DNT1
09-13-05, 08:32 PM
Have noticed some whistling on some zoned systems with a bypass damper at startup is this a zoned system per chance?

Grady
09-13-05, 08:57 PM
If the lines from the outdoor unit are in the wall near where you hear the noise, it could be the sound of mixed gas & liquid refrigerant in the high pressure line. After a few seconds to maybe a minute, the gas & liquid are separated & the noise goes away until the unit has been off for a while & comes back on.
timmyg123
09-13-05, 10:06 PM
If the lines from the outdoor unit are in the wall near where you hear the noise, it could be the sound of mixed gas & liquid refrigerant in the high pressure line. After a few seconds to maybe a minute, the gas & liquid are separated & the noise goes away until the unit has been off for a while & comes back on.

This sounds most probable.
Is there a fix?
Grady
09-14-05, 04:14 PM
No cure I am aware of, sorry. You might want to have the refrigerant charge checked but I doubt seriously it will make a difference.
I know it won't make you feel any better but mine does the same thing. When I hear it, I think "OK the A/C is working".
Rob61
09-23-05, 07:14 PM
I ran into this some years ago, it was on a york system. The freon would go through the lines a littler quicker.

The fix was (as silly as it sounds) to put mufflers inline between the compressor and coils on the outside unit. (as per york they had to be silver soldered)

we had 3 of these in 1 house and it drove the owner nuts till it was fixed.

After the recharge and startup there were quiet as a mouse.



Rob
Retired due to injury HVCA Tech.