My brother-in-law's 2006 E350 passenger fan has cold AC from the dash vents but ambient air from the ceiling vents. The system has front and rear blowers, blower dials and evaporators but a single thermostat dial. I think either the rear expansion valve is bad (it would have a rear expansion valve if it has a rear evaporator, right?) or the evaporator is beyond clogged. There's good airflow from the ceiling vents so it has to be a bad expansion valve. Anything else it could be? The van's in the shop today.

Sixto
87 300D^2

Most likely the expansion valve in the rear unit. Front unit uses an orifice tube. You can get to the A/C lines for the rear unit by crawling under the vehicle where the unit it (I think it's the left hand side) and feel the lines to see if the suction line is cold. If not, the expansion valve is clogged or failed. Make sure there isn't debris in the system, such as from a failed accumulator.

A less likely failure is the temperature blend door no longer operating and being stuck in position.

Either way, the E-Series dual A/C units really don't cool all that great in hot weather. 60°F at the vents is considered acceptable according to the manufacturer temperature-pressure charts for normal operation.

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Erich Loepke
2010 Ford Focus
Currently Benz-less