Outside A/C unit makes high pitch noise when turned on
I am a builder. I have a homeowner who has 3 Trane A/C units. It took a while to distinguish which unit was squeeling. But we now know that when the second floor unit comes on the A/C compressor on the outside make a loud squeeling noice that wakes the homeowner at night. It makes the noise for 30 seconds or less. My sub that installed the units is having a hard time figuring out the problem - mainly because the noise does not last very long. Any ideas?
Thanks
:confused: