Interesting problem I've seen a total of 3 times now...and I haven't a CLUE. Nor does Carrier or Trane tech support.
I've had this happen on a Trane Package Heat Pump, York Heat Pump and Carrier Straight A/C.
The condensor fan assembly is running but doesn't move air UP and OUT of unit. Instead it seems to kick the air off the sides of the unit, which includes pushing it through the top of the condensing coil. I've replaced the motor and blade on the Carrier and Trane units but it doesn't solve the problem. This is causing very little air to be moved across the coil and is resulting in very high head pressure. Has anybody ever seen this? And if so have you found a solution?