not had the problem but there are 2 versions of that model. with different thermistor part numbers. APM6855 0:
502023500 NO FROST RADIATOR PROBE 1
502023400 FREEZER AMBIENT PROBE 1
and APM6855 1 which is from jan 2007:
502055800 APM6855/1 NO-FROST RADIATOR PROBE
502055700 APM6855/1 FREEZER AMBIENT PROBE