Trane XLi16 unusual sound

[drose224]

I live in Bucks County Pa and recently my heat pump has been making an unusual sound outside. I have emergency heat set to come on at 20 degrees. At 34 degrees like this morning, just as the outdoor unit is shutting off it makes a sound I can only describe as a donkey uttering a death bray. It's loud enough to clearly hear in the house and only makes the sound when the outdoor unit is shutting down after inside temp is reached. What makes this really crazy is it does it sporadically and I know if I call service out it will make the noise.

Any ideas???

Thanks

[toddestock]

check to see if you have 2 compressures i belive that is the 16 i the 19 i has 2 stage compressure sound like both compressures were running when they shut down the pressure equlizes between the two

[mark beiser]

check to see if you have 2 compressures i belive that is the 16 i the 19 i has 2 stage compressure sound like both compressures were running when they shut down the pressure equlizes between the two

The 16i has one 2 step scroll compressor.
The 19i has 2 compressors, both never run at the same time.

[snuffy collins]

I live in Bucks County Pa and recently my heat pump has been making an unusual sound outside. I have emergency heat set to come on at 20 degrees. At 34 degrees like this morning, just as the outdoor unit is shutting off it makes a sound I can only describe as a donkey uttering a death bray. It's loud enough to clearly hear in the house and only makes the sound when the outdoor unit is shutting down after inside temp is reached. What makes this really crazy is it does it sporadically and I know if I call service out it will make the noise.

Any ideas???

Thanks

if it is a scroll compressor it may be internal check valve letting gas by and making it run backwards momentely.