My 2012 VW Passat SEL has dual AC Zones. The driver's side is working fine. Hot and cold air. However, the passenger side AC is blowing what seems to be the outside air (on the really hot days it blows really hit air, and at night it blows not such hot air, but not cold air). When i turn on the AC on cold i hear a mild (hard to describe but sounds like a hissing) sound coming from the passanger side front area when driving in low gear.

I have been told it is possible that the flap that moves the air is broken, or the passenger compressor is broken (are there two compressors?).

I do have the cheap OBD2 (OBDII) scanner but it gave me no information about the AC system. Would AutoZone or a similar store scanner be able to pin the issue?

In reality, what would be good troubleshooting ideas/steps? Any ideas on a fix?

  • There is a button on AC control unit "DUAL" or "SYNC". Does the problem you mentioned repeat when the button is on/off? – coner Jul 11 at 14:49
  • @coner the passanger's side AC is never blowing cold air (unless its cold outside) regardless of the dual or sync setting. – KingsInnerSoul Jul 11 at 14:56
  • I don't think the car has two compressor. But maybe using wrong coolant clogged the system. Have you changed the coolant fluid recently? – coner Jul 11 at 15:06
  • @coner i haven't changed coolant. And they won't do that during an oil change either. – KingsInnerSoul Jul 11 at 15:10
  • @coner thinking about it, if the system is clogged, wouldn't that mean that both sides wont be producing cold air? In this instance only the passenger side is not cooling. – KingsInnerSoul Jul 12 at 21:07

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