Actuator For Temperture Flap At Rear

[cjblues]

Hi, I've an 1.9 Diesel Galaxy on a 02 plate, with Auto Air Conditioning/Heating (no rear a/c).

 

The control unit has started flashing for about 10 seconds when the ignition is turned on which indicates a fault.

 

The diagnostics shows fault code 01187 (Actuator for Temperture Flap at Rear).

 

I've not been able to find out what this actually is, and the Ford Dealer couldn't find anything obviously wrong.

 

Any ideas ?