Hi Peter

No.
You must set the bits of ADCON0.
If bit 6=0 ...Vdd is reference.
If bit 6=1 ...AN1(GP1) is reference.(To do this you must set GP1 is analog)

You can find details on page 43 of 132 of Microchip Pic 12F629/675 data sheet.
(www.microchip.com)

a.majid