Hi - long time owner, first time poster... My A/C is only working for about 30 seconds and then although the blower continues (I can hear it loud & clear) the vents all shut and no cold air goes through. If I switch the A/C button off & then on again, the vents open - it immediately blows lovely cold air and then again after 30secs the vents close. Any ideas? Seems like a vent actuation issue rather than a compressor issue. No DTC error codes.