Had a new lennox high eff ac installed 6 years ago. Had it serviced this
year to clean the A coil. Week later the unit is out of freon. Called
themback and said it was most likely the A coil leaking although he could
not find the leak. Finally got a hold of the orig installer (diff co) and
he came over and pump it up at n/c 9 pounds of freon and a day and half
later the compressor shuts off due to low pressure (out of freon again).
Both techs cannot find the leak.

Leaking that fast should'nt it be easy to find the leak? Far fetched ?, but
could it leak on the pipe run from the compressor to the a coil somewhere
due to a crazy vibration that wore a hole in the line?

2nd tech says he soaped the a coil and used his leak detector and could not
find it leaking on the a coil.

What should I ask the tech to do to find the leak? Whats the proper
procedure?

thanks.

Mango