I'm trying to fix an old fridge/freezer about which I can find hardly any technical info. It's a Lec T663AW with a ZEM HQY90AA compressor, rated at 1/6HP. The 4uF run capacitor is OK, also the windings (22/25ohm) and the overload too. It doesn't have a proper relay as such, just a PTC. On opening that unit, parts of the silver disc PTC fell out. The plastic exterior shows slight signs of overheating. I've no idea if the unit's exterior markings ARB2 7100D4 meaning anything.

My hope is that, with a new PTC unit, it might be fixable. I've found a visually identical unit, currently on its way (via the slow boat from China), though I cannot know the PTC's suitability to my fridge.

The old/broken PTC unit, of which three quarters of the silver disc remains intact and in place, gives a 8.4 ohm resistance. My assumption is that the missing quarter would have reduced the resistance to a lower figure. I have found general comments suggesting 3 to 6 ohms is common, but having also found a Chinese supplier of these silver discs, I have seen values from 4.7ohms to several tens of ohms. Not so clear then.

My assumption would have been that a fairly small fridge/compressor would have needed less starter current, and so a higher PTC resistance. But the existing 8.4 ohms of the three quarters intact one is making me look towards the 4.7 ohm one.

Can anyone offer any advice on, in the absence of detailed tech info, what value PTC it might need? I don't want the thing to quietly overheat if I do get it running again.