Mazda 626 coolant fan polarity reversed?

What could cause a coolant fan to shut off when the engine is hot but to
run the rest of the time? The radiator temperature switch is new, (the one
near the thermostat housing). The only other sensor is at the bottom of the
radiator, but that's supposed to be for heater/air conditioner. Is there
some relay or other contact where the polarity could be reversed to make
the fan run the opposite of that it's supposed to do? Or could it be the
ignition switch, like someone suggested to me? This is on an '87 626
non-turbo.

It might be a relay wired wrong, i.e. connected to normal closed instead of normal open contacts.
A sensor near the radiator outlet (bottom) usually controls the fan.

Bichette wrote:
>
> What could cause a coolant fan to shut off when the engine is hot but to
> run the rest of the time? The radiator temperature switch is new, (the one
> near the thermostat housing). The only other sensor is at the bottom of the
> radiator, but that's supposed to be for heater/air conditioner. Is there
> some relay or other contact where the polarity could be reversed to make
> the fan run the opposite of that it's supposed to do? Or could it be the
> ignition switch, like someone suggested to me? This is on an '87 626
> non-turbo.

--
Mike Walsh
West Palm Beach, Florida, U.S.A.

mazda has three sensors for coolant 1)temp for gauge 2)temp for computer
3)low coolant a fan can run
reverse but not likley it requires special tools to swap wire connectors
in the plug. ignition switch no!
does the coolant fan come on with a/c on?
with the a/c on is the fan pulling air through the condensor and radaitor?
if the fan is blowing forward (polarity must be correct)any more questions
e-mail good luck

There is no a/c on this car. I'll check the fan direction. Thanks for the
info on coolant sensors. I'd never heard about the temp sensor for
computer, but doubt that could cause the fan to run from start-up. I
replaced the sensor on the block, which I think is the guage sensor. The
one at the bottom of the radiator checks out okay with an ohm meter - no
connection when cool, yes connection when hot. A dealership suggested the
ignition switch, since it affects other things like turn signals,
windshield wipers, etc. when wires in the electrical part get melted. The
switch was recalled about 12 years ago & got replaced at that time, but
could have gone bad again. I don't look forward to taking the steering
wheel off to change the it though.

There are 3 relays in front of the engine on the driver side. A dealership
said that one is the main relay, one is the fan relay & one is some other
relay. They let me try a new fan relay, but that didn't fix the problem.
Are there other relays to check somewhere else?
The sensor at the bottom of the radiator checks out okay with an ohm meter
- open when cold & closed when hot.