Prem i air dehumidifier fan runs but compressor will not start up?

I have a Premiair PDEH2020, it is only just over 2 years old, last year (just after warrenty ran out) it stopped working and I phoned the helpline and purchased a new pcb board and thermostat and it has worked fine for the last year but now just after emptying it the fan runs but the compressor will not start up, I phoned the helpline and of course the company has been taken over and the technical section was of no help and I could not get through to the spares department.
I am wondering if itcould be some sort of cut out switch or is it likely to be the compressor itself, I do not want to waste money trying too many bits if it is likely to be the compressor.
Any help will be appreciated.
Thanks Tricia.