Specimen head temperature problem

Specimen head temperature doesn't work I changed the Peltier object and checked in the service mode how much current it draws only 1600mA comparing to the original one from anther cryostat x50 that draw 2400mA and the temperature reaches only -3 in the best cases. so is the problem the new peltries because i,ve changed twice and still the problem occurs please help thanks Mohannad