We have an engine-driven refrigeration
system (we have a 12V system in parallel, but that's another story). The compressor clutch
excitation line runs through a manual switch and an oil-pressure switch, in series. That way, the clutch
circuit is disabled whenever we want it to be or when the engine
We live aboard, almost always at sea or at anchor
, and use the engine-driven fridge system almost daily. The oil
pressure switch gives out regularly. Not every month, but more often than once a year.
We actually have three oil-pressure switches aboard, one for each alternator
and the one for the fridge. The two alternator
switches have worked fine for decades, without replacement. Any idea why the compressor
clutch circuit is different? The only thing I can think of is current
-- the other two circuits are sensing only, no real load.
And what is the solution? These switches are hard to find, at least in the more developed parts
of the world. They have two poles and screw into an oil
pressure manifold. It turns out (I have a lot of experience with this) that there are two thread pitches. Ours is more common, and in some places (Morocco, Panama) our switch is widely available -- just walk into 3 or 4 little family-run stores and ask for one, and one of the stores will have it. I can't find them at all in the US, having visited just about every chain auto parts
store there is (Napa, CarQuest, Pep Boy etc.). Of course, I'm hampered by not having a car model to give the clerk -- amazingly, none of their databases can be searched by part type. But eventually the clerk goes back into the shelving and looks for anything that appears to be similar to the old switch I've brought along. This is the one quest I've found easier to carry out in Spanish or French than English!
Anyway, suggestions are welcome. Meanwhile, I can simply short across the switch and we have to remember to turn the fridge off manually. Otherwise, we'll burn the clutch out in short order (been there, done that).