Have '03 S-80 Volvo. AC work fine until car idles. Everything continues to work but no cold air. Switch off AC (only)…wait few minutes. Switch AC back on. Cold air returns. Added refrig. Made no difference. What could be my problem?
Make sure the engine fan is working properly. If it does not kick on when the engine heats up the AC will operate poorly. The AC condenser sits in front of the radiator and the only way the refrigerant gets cooled at a standstill is by the engine fan pulling in cooler air.
On some cars (I believe that includes at least some Volvos there is a blend door that is vacuum controlled. A leaking vacuum hose could be the problem.