Whirlpool refrigerator behaving oddly

This is a 1979 Whirlpool refrigerator, model EET-172PK.
I was in the kitchen for a couple minutes this morning and noticed that the compressor was attempting to cycle ON about every 20-25 seconds, but only staying on for maybe 3 seconds. The evaporator fan motor feeding the freezer compartment was running continuously, cool but not icy. The condenser coils were not hot to touch as they normally would be when the compressor is on.
So I quickly cleaned the dust out of the condenser coils, but that didn't change anything. So I thought that for whatever reason there wasn't enough freon for the compressor to run.
Then after a few more minutes, the compressor turned on, and stayed on, and appears to now be running fine - hot condenser coils and all. It has now reached the trip point of the thermostat, and turned off as it normally does.
So I'm wondering if maybe this is what's happening: this morning I caught it in the middle of a defrost cycle, when the compressor and fans should have been off, but weren't. So there may be a switch, or a clock of some kind that controls the defrost cycles, and it's not disabling the compressor fully during defrost like it should, but there's an additional backup safety switch that's shutting down the compressor when the heating coils are hot.
Does this sound reasonable? If so, is it possible to get to the defrost clock and switches? Where would they be? And is it possible to get a replacement for whatever assembly that is, or even fix it? I have this image in my mind of a switch carrying power to the compressor that's supposed to open during defrost cycles (cam-driven, probably), but is fused closed. Or maybe there's some crud in the way. Or maybe a cam lobe broke off.
Anyway, what do you think?
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On Tue, 18 Oct 2011 13:30:47 -0500, Peabody wrote:

Hmm, ours is an EEB-191PKWR1, dating from around 1977, which was in the property when we bought it. When we first moved in, it was off and unplugged (and room-temp, obviously) - when I first plugged it in, it gave exactly the same behavior as yours, cycling and eventually starting up properly.
It's been running fine for over years since, and has never had any problems after the power's been out. I figured at the time that I'd investigate more when it broke next, and maybe even replace it, but so far it hasn't so much as coughed (but the freezer compartment fan bearings are noisy, and some of the plastic fixtures inside have seen better days - so SWMBO sometimes bugs me about a new one :-)
I'm not sure if mine has any kind of auto-defrost, though. *if* it has any kind of timer mechanism, I expect it's behind the controls in the back of the fridge compartment - but I'm not sure it's laden with such new-fangled tech ;-) As yours is a little newer, maybe it does have a few more smarts, though.
cheers
Jules
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Is it a self-defrosting model?
Just leave it alone if everything is running ok now.
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