My fridge freezer is in my garage and defrosts at low ambient temperature. Switching to fast freeze froze the freezer but also froze the contents of the fridge and spoilt them.On my fridge freezer the fast freeze switch is a hard wired switch which I have to switch on and off, it does not time out as on some models.I have used a plug in lighting timer normally used to switch lights on and off which has 1/2hr settings (one with 1/4hr settings would give finer control) but mine seems to be working fine. I have set it on for 1/2hr and off for 31/2hr (totalling 4hr) 8 times round the dial. The fridge freezer is plugged in with the fast freeze permanently turned on. I have monitored fridge temperatures between 0/5C and freezer temperatures between -24/-20C so the timer is closely imitating the thermostat control. The refrigerant cycle is obviously working at the low ambient in my garage (-1/+6C during the cold spell). I cannot comment yet on whether there will be long term degradation of the coolant but at least the fridge freezer works at the moment
Peter, March 2009