Assume you have checked the fuse in plug is Ok,
If unit is less than five year old suggest you phone Hoover at 01204556111 Have Model number and serial number to hand You may find replacement parts are free We discovered Hoover offer a very good repair deal when 4 year old frost free model HNMF2805AL faled. This model has a circuit board in place of a thermostat
Scot, February 2011