Fan sensor..

[BrianO]

Update 12-8-07 - save you from reading 5 pages...
SUCCESS!!!!!

man this makes my day!!!!

this morning I did the back flush of the system, didn't change..
I replaced the guage sender just for the hek of it since I have 3 sitting here.

I removed all the little lines near the fan switch and cleaned them all out, some debre in there..

filled again and now heater is HOTTER than it's ever been, guage works as it should, and gues what??? the damn fan switch CAME ON when it was supposed to...right between the A and the L....works like a charm now. I let it idle for a few minutes and it came on twice, cooled down, then heated up...etc...

WOOOHOOOOO!!!!!!!!!!!!!!!!!!!!!!

that is all.





WTH??

see attached photo.. the smaller sensor is the one that was on the car, I replaced it with the other one, the larger one. The first one didn't work, the second one worked one time only so I replaced the second one with one just like the first one and now the fan stays on all the time...

UPdate....I've tried 4 different sensors at this point I fail to see how they could all be bad. here are pics of the switch setup...if you have any ideas please let me know.. I'm way past being frustrated at this point.

see attached photos....
temp picture..I let it go WAY past this and nothing

setup picture ---shows where the switch is and how it's plumbed on an 86

wire picture -- a patch, just hooked it to ground and the fan comes on

[Eyelawdoc]

The sensor on the right is the correct switch for the cooling fan, even though it failed shortly after installation. The sensor on the left is the one properly used for the temperature gauge. It will screw into the orifice used for the fan sensor, but will cause it to run all the time as you have experienced.

Try another supplier for the cooling fan temperature sensor. I've had good luck with Autozone ones.

Don't laugh. They work better than the Ford originals. I've replaced many in the "fleet" over the years!

[BrianO]

interesting.. autozone actually has the one on the left listed as the coolant fan sensor..part number TU25, although as I pointed out when I got home was that it looks just like the temp sender one..just like you say.

ok, well I'll go look again for the correct one.
thanks

[Eyelawdoc]

For an 84 or early 85 the Autozone part number you need is SW501 for the cooling fan temperature sensor.

[BrianO]

yep, found it after some searching and just went to get one. I never kept the reciept for the first one..only 2 weeks old so I had to buy a new one..

reminder..KEEP RECIEPTS

[Eyelawdoc]

yep, found it after some searching and just went to get one. I never kept the reciept for the first one..only 2 weeks old so I had to buy a new one..

reminder..KEEP RECIEPTS

If you got the one that failed from Autozone, it has a warrenty (something like 45 days or so). They should replace the bad one for free. Even if you loose the receipt they can look up the warrenty for the part on their computerized warrenty system.

[Pat_in_L.A.]

That's the nice thing about AZ and Kragen. You don't need the receipt. They keep your warrantied parts on file in their system. That's why they ask the info they do when you buy the part. I have several "limited lifetime warranty" parts from them on my car and have never needed a receipt. One example is the brake pads on my wife's Mercury Sable. As long as there is brake pad left that hasn't gone metal-to metal, they just hand me a new replacement set whenever they get thin.

[BrianO]

that particular part from autozone has no warranty..so that's two I've purchased so far...do you know...it STILL doesn't work.

I can unplug the wire, touch it to the fender and the fan comes on, plug it into the sensor...NOTHING... that's 3 all together.. WTF???

I fixed the EGR that was leaking..it was cracked. Stopped by motion and got another one.

what's with this stupid sensor? it's hot as hell down there too, no reason it should work for a second time.. I'm stumped

[BrianO]

yeah I thought it was 220 or something, that's what Jim said at Motion.

well, I did let it get hot, but at first I left the cap off so I could burp the system of air. I'll let it run again with it sealed and see what happens. I just don't like letting that needle get to the "L" in Normal..

I'm running about 80/20 coolant/water

[Eyelawdoc]

When you take the sensor out of the threaded hole, does coolant run freely out of the hole? Corrosion can build up in back of the sensor, sealing it off from the coolant so it never gets hot enough to turn on.

If you tried to get the car hot enough to turn on the snesor with the cap off the raidator that won't work. The coolant won't get hot enough to activate the sensor unless the system is pressurized. The sensor should turn the fan on somewhere between the A and L in normal.

[Eyelawdoc]

Alternatively, Kragen offers the Niehoff TS25711 (formerly FF 135) for $11.99 or the Ready-Aire 5031 for $ 9.79. Both have a 1 year warrenty.

[BrianO]

removing the sensor coolant will drain with no restriction.

I've let the car idle witih cap ON until the gauge goes all the way past the L in Normal to the red....after that I remove the wire and short it so the engine doesn't over heat. the first replacement sensor kicked the fan on right at the M.

this is two sensors from Autozone, both SW501

[Oldham_Racing]

have you tried an orielly's sensor yet? go try a borg warner or a borg warner "Select"...

i realize i work for orielly's but i still have not ever had bad luck with the borg warner line of electronics...

[Eyelawdoc]

Hmmm... it should definitely come on by the time the needle hits the L. Kicking on at the M is ideal.

Are you using any teflon tape or other sealant on the threads that could possibly interefere with the electrical connection between the threads of the switch and the threads of the hole?

[BrianO]

I have not tried an Oreilly's one yet, but was going to take back the autozone ones and go to Napa.

yes I did try the sensor with and without tape on the threads and I even backed the sensor out a bit to make sure coolant was running over it. I find it hard to believe 2 sensors in a row, but who knows.

The first SW501 replacement turned the fans on and i was happy, but that was the last time it worked. Right when the temp hit the M the fans kicked on.