Re: [DML] Cooling system

["Walter" <Whalt@xxxx>]

David,

You say that your fan fail light flickers and the fan relay clicks
frantically sometimes when the fans come on. It shouldn't do this. I am
suspicious that you have a bad otterstat. This gadget is a switch that is
activated by a bi-metal strip. Two different metal alloys are layered
together. One alloy is more temperature sensitive that the other, so when
the temperature changes, it tends curl or warp. This triggers the switch.
It sounds like your problem may be that something inside this switch is
loose. When working properly, it is supposed to switch off when at several
degrees cooler than when it switched on. This is supposed to reduce the
chance of rapid cycling. In your case, it sounds like this mechanism has
gone to the other extreme where the coolant has to be luke warm before the
otterstat will switch off. When the switch comes on, it may be holding the
contacts closed with only mediocre force which would explain your flickering
light and chattering relay.

I have done this test before: take the otterstat out and put it in a
shallow pan of water with a thermometer. Heat it on a stove with a
continuity meter allegator clipped to the otterstat. You will be able to
see at what temperature it switches on and off. While you are at it, check
your original otterstat the same way and compare. Since you seem to be
having such bad luck with otterstats, I suggest checking any new ones the
same way before you put them on the car.

Let us know what you find.

Walt Tampa, FL