Thermocouple sensor for rad. fan

[ericsmith32]

According to the haynes manual only when warm I should get a ohm reading. Right now it's in the low 50's and I checked the sensor and I got a no resistance at all -basically like a straight wire - this is from the prong and housing. Since it's been getting cooler I've had the problem of it not wanting to start after its set a while. I noticed today the fan running when I was trying to start it this morning. In my eyes this sensor is bad.. any objections??

PS On a side note I thought the computer read the temp through the one in the block on the front, so why am I having problems starting it? This is on a 91 festiva btw.

[mechanicaldj]

to put it simply ,if you disconnect the wire from the sensor while the engine is running , the fan will come on.

if your fan is on all of the time, there is an open in that wire or your cooling fan relay is stuck

or if you have a/c , a/c relay #1 may be at fault

[ericsmith32]

I normally test the fan by unplugging that sensor. When I unplugged it, it continued to run, and when I plugged it back it still ran. The funny thing is that the new sensor read the same as the old, but the fan didn't run. So as I like to say... only time will tell.

[festivaaah]

I"ve got an 89 carb'd festiva i just picked up...

my fans aren't turning on....

I've checked the fan motor itself by unplugging the connector that it right near it, and applying power...it workd fine.. the terminals on the connector were oxidized so i scraped them clean...but it still doesn't turn on by itself....I"ve also checked the fuse under the dash


can someone tell me where the sensor and relay are for this? ccasion5:

and how do i test which one is faulty...the sensor or the relay

[ericsmith32]

It's on the thermostat housing, to test remove the wire and the fans should turn on. The relay is on the drivers side, black and yellow and is a pain in the butt to remove. Is it overheating?? It takes alot for the fans to turn on, small engines doesn't create alot of heat.

[Safety Guy]

I don't recall the fan in my '89L ever running at all.

I think it would take a 110 degree day with a full load of trailered camels in the desert sanddunes to overheat that car--if I get it running right ever again.

Karl

[gdawgs]

Yep, I think my fan comes on maybe 3 or 4 times/year.

[festivaaah]

yea it's overheating...the fan doesn't come on at all...

[festivaaah]

ok yea...so i unplugged the sensor...fan came on....




so what's the dilly?

to me that sounds like the wiring is good...so it is likely be the relay?

[FB71]

so is that "festivaaah" like at the doctors' or dentists', or like post - orgasm?

[festivaaah]

so is that "festivaaah" like at the doctors' or dentists', or like post - orgasm?

neither...


it's me screaming down the road in fear as i bury the needle at 140kph! hahaha

[ericsmith32]

What shape is your cooling system in? Have you flushed it lately? New coolant? Also a stuck open or closed thermostat can cause overheating. The best way to test the switch is in boiling water at certain temp, at a certain temp it will cause a open circuit 0 ohms, closed it should read nothing. Is it boiling over? If you just changed the coolant it will steam up for a while so don't mistake it for overheating.

[festivaaah]

the car is definatly overheating ...and it is caused by the fans not coming on...i know this because when i had the car on the dyno for an emissions test they had no fan in front of the car and it overheated....i looked and the fan hadn't come on in the car.....

[Champ 98]

I would wire the fan direct, with a simple switch in the dash. We have done this several times with a few of our racers. A rear defog switch works great and looks OE.