My ( end of 2013 ) 2.2d 175 hp engine power is cut-off from time to time, and the warning "Engine not cooling" is displayed.
The problem occurs more often when the A/C is turned ON. If i turn the A/C Off, the engine runs pretty ok.

The issue occurred after i've changed the serpentine belt tensioner along with the belt.
Is there are chance they could miss install the belt or use a longer version with can make the water pump slip ?

The service guys said i could maybe have blown the head gasket, but i have no oil in the coolant, coolant in the oil and the coolant hoses are not rock solid.

Any suggestions ?