American Whirlpool catastrophic defrost

Hi,
After searching threads in vain for the answer to my problem, i decided to start a new one. Our Whirlpool ARZ740/S packed up on christmas eve, as did our washing machine but that’s another story…

The Whirlpool is I think about 12 yrs old,and it says “made in USA”. It’s old enough not to have a display, and the only controls are two sliders: off/freezer temp, and fridge temp. It’s been fine in the four years since I got it, but has now totally defrosted over a 24 hr period.

The compressor seems to be humming as usual, but the compressor cooling fan exhaust seems to be at room temp so it can’t be generating much heat, therefore it isn’t doing its job. Uncooled air is being blown into the freezer compartment so it reached room temperature within a few hours, and the fridge followed suit.

I have hoovered out dust although the symptoms don’t suggest a gradual loss of efficiency. I had the lower back cover off and there was no water in the evaporation tray.

I have turned the appliance off for 48hrs and there was no sign of any meltwater. I restarted it about half and hour ago but am still not getting any cold air.

From the above symptoms, can anyone give me any clues as to whether this is economically repairable? I know the cost of a compressor would be prohibitive, but could there be some kind of controller fault?

Or should I just get down to currys before the sales finish? I’m tempted, because they are offering £30 off washing machine and f/f bought together.

THanks for reading this.