Adler Barbour Coldmachine

Ok, gang, We've got two boats with old AB Coldmachine fridges. Our Cal has the temp knob in the fridge box, where you'd expect it :-) The other boat has the knob in the lazarette, where you wouldn't expect it, although it is close to the compressor. Are these knobs simply electrical "rheostats" or do they have a temp sensor built into the assembly? If they don't, is the temp sensed at the compressor and based upon coolant temp vs knob setting? I'm only going on memory here, no access to either boat just now, but I thought maybe there was a metal tube running to the knob/temp assembly as well as wires... Thanks, Peter Cal 39 Ontario 32

The Cal probably has has a cap (capillary) tube that runs either to open air or it could be clamped to the evaporator tubing inside the fridge. There is probably a bulb on the end of the cap tube. The gas inside the cap tube exerts a pressure on a diaphragm that throws a switch on or off. This obviously stops and starts the compressor. The other system may have a connection from the switch to the suction line near the compressor and it reads the suction pressure directly. It also would have a cap tube between the switch and the connection to the suction line. The connection at the suction line could be soldered (most likely) or it could be a mechanical connection (flare nut). Which one is used is entirely based on the whim of the engineer that designed the system. Unless someone did a retrofit. Walter MacArthur '70 Cal 34 "Tejana" C. Peter Audet wrote: > > Ok, gang, > We've got two boats with old AB Coldmachine fridges. Our Cal has the > temp knob in the fridge box, where you'd expect it :-) > The other boat has the knob in the lazarette, where you wouldn't > expect it, although it is close to the compressor. > Are these knobs simply electrical "rheostats" or do they have a temp > sensor built into the assembly? If they don't, is the temp sensed at > the compressor and based upon coolant temp vs knob setting? > I'm only going on memory here, no access to either boat just now, but > I thought maybe there was a metal tube running to the knob/temp > assembly as well as wires... > Thanks, > Peter > Cal 39 > Ontario 32 >