More a/c questionable info

[Jerr-conn]

I bought my 87 Chevy swb 350/700r/4 a year ago Jan. The a/c didn't work, although it was all
Hooked up. So, I took it to this reputable service center to ck it out. They worked on it, refilled it
With r134 ( it was already converted ). $125 later , it worked good. That was last year. This year
When I went to use it , nothing. Took it back , they said it must have leaked all refrig out during winter because  of no use. In my reg cars, I don't use the a/c in the winter and it still works in
The summer. Compressor won't turn on either. I don't know a/c, but this don't sound right to me.
Need help. Thanks. Almost forgot. They did not ck out with die in system.

[bd]

The shop's response is feasible.  A/C compressors are energized whenever Defrost is selected.  This is done to dry the air before it reaches the windshield so that moisture laden air doesn't condense and film the interior surface of the windshield, obscuring driver visibility.  When the compressor is energized, the circulation of refrigerant through the system also circulates oil, coating the seals, which helps to minimize refrigerant leaks.  If the A/C compressor front seal isn't in pristine condition, seasonal non-use of the A/C (defrost) can allow refrigerant to leak past the compressor seal as the seal "dries."  However, refrigerant can leak through the tiniest of holes, so no assumptions should be made as to why the system has emptied without proper testing.

A workable approach is to inspect all hose connections, Schrader valves and the compressor clutch area for any evidence of oil seepage.  Recover any residual refrigerant, install new Schrader valves then evacuate and charge the system adding an appropriate amount of dye, followed by a thorough check for active leaks.  The use of dye is a secondary diagnostic measure most useful over the long term.  For primary diagnosis, a technician should use an electronic leak detector that is sensitive to the type of refrigerant used in the vehicle.  Only through proper diagnosis can you ensure a lasting repair.