A/C Fan won't turn off...ever

[McPants]

Bernie, ive sent you a pm

[Bernie351]

Thanks mcpants
Ive done what ausblue and mcPants suggested..
Great tips and pics..

Spent last 4 hrs replacing transistor, and swapping relays...bought new soldering iron.

But same :(
Anyone else have any luck?
I spent all my cash on this car...cant afford to pay ford or auto lec
Fan doesn't stop when I pull fuse or relays.
Ive disconnected wires behind glovebox (brown plug)

ps. mine is a AU LTD V8

[aussiblue]

Any chance you inserted the transistor the wrong way around? Did you use new mica or rubber isolation washers? Check with a multimeter that there is no continuity between the transistors casing and the finned controller casing.

[Bernie351]

I did watch the pins when I put it in, and put it in same way (pins closer to one side)
But no markings? so hard to tell?
washers? I didn't see any?
I took the old transsister to the auto lec to test...no word yet.

[aussiblue]

washers? I didn't see any

That's the problem then.
You need insulating washers and eyelets like this otherwise the transistor will short to the fan speed controller case and fail. :

so the transistor case is electrically isolated from the case of the fan speed controller.



The eyelets are not labelled (they are the black items but the fit in the screw holes so the screws don't connect the case to the transistor. The isolating pad/washer can be mica or rubber and needs to be covered with heatsink paste so the heat but not electricity can move between the transistor and the finned case of the fan speed controller.

Mica washers or isolating pad:

[aussiblue]

This may help http://www.youtube.com/watch?v=hNRacVQRgBc


and http://www.youtube.com/watch?v=nPpPWSrrxfM


and for some theory:

http://www.youtube.com/watch?v=8ruFVmxf0zs

[aussiblue]

Original link was http://www.fordforums.com.au/showthread.php?t=11395945

[aussiblue]

Note, that if didn't use the eyelets and insulating washer/pad you will have replicated the original failure when wet leaves short the TO-3 transistor to the case of the fan speed controller (or corrode its case) and killed your new transistor.

[aussiblue]

TO-3 Mounting kits are available from:

Altronics: http://www.altronics.com.au/index.as...=item&id=H7200
Jaycar: http://www.jaycar.com.au/productView.asp?ID=HP1172
Element14 (Farnell): http://au.element14.com/keystone/472...tor/dp/3299776
Futerlec http://www.futurlec.com/HeatAccess.shtml
RS Components http://australia.rs-online.com/web/p...ories/0263239/ and http://australia.rs-online.com/web/p...ories/0298493/

and if you want to socket it: http://australia.rs-online.com/web/p...ories/1897912/


and heatsink paste to coat the pad:

Altronics http://www.altronics.com.au/index.as...=item&id=H1600
Jaycar http://www.jaycar.com.au/productView.asp?ID=NM2010

etc

[McPants]

your a wealth of knowledge blue. I don't own my Fairmont anymore, but do miss that effortless steering and 4ltr power. my new cars engine is half the size.

[aussiblue]

and there's always eBay

http://www.ebay.com.au/itm/10-Sets-M...item20d35aa065
http://www.ebay.com.au/itm/30g-Therm...item43bbc84643 etc

[Bernie351]

hey great work bluey
il get wifey to leave LTD at home agin and il have another try..
I bought the transistor from jcar...so will go back and get other bits and try again.

went to 2 auto lecs and big computer shop
no one knows how to test transistor??

stay tuned...I might video it for the next poor Ford owners hahh
Bernie

[Bernie351]

checked the old transistor...
sure enough found the washers under the coating

[aussiblue]

Most multimeters these days have a transistor testing function and the specs for most transistors are available online. i.e. in this case http://www.futurlec.com/Transistors/2N5686.shtml
http://www.onsemi.com/pub_link/Collateral/2N5684-D.PDF
http://pdf.datasheetcatalog.com/data...emi/2n5685.pdf

[Bernie351]

Originally Posted by dnk

I had the same problem, but couldn't source the transistor. A 2N3055 from Dick Smith or Jaycar works just as well. You might want to replace the transistor's insulator washer and bushes as well.

DAM, this was the step I missed :(

[Bernie351]

FIXED
Thanks bluey and others..
Got the parts from jcar ($8)
the insulators listed didn't fit, too small for the bolts?
I changed the bolts to suit and whacked it back together ..
woohoo...we have a heater again..

These forums are great

[monaroman]

Awesome thread guys, just what the doctor ordered, followed aussieblue's instructions on a AU series 2 fixed the problem in about 2 hours, thankyou to all who have contributed info here, cheers

[mwoonkey]

Originally Posted by aussiblue

The main transistor in the fan speed controller that sits in the a/c air intake duct to keep cool will have corroded and shorted. Leaves and moisture get caught in the duct sit on the transistor casing and rust it away. Replacement transistor can be had from Worldwide Electronics http://members.iinet.net.au/~worcom/ for less than $15. The symptom of the transistor's failure is a fan that stays on high speed or stays on all the time.

The transistor is Motorola 2N5686 (Ford used to own Motorola). The fan speed controller box (silver metallic held by two screws behind glove box) opens easily by bending the tabs and its not too hard to unsolder the transistor and replace it - just ensure the orientation is correct so you don't reverse wire it (very easy to do as it seems to fit better the wrong way around).

To prevent the transistor failing again I suggest you add a TO-3 plastic cover (Cat ZM-0004 at Jaycar, Cat H7290 at Altronics, Dick Smith have them but I can't find it in the catalogue) and /or an additional TO-3 heatsink (part number H3400 at Disk Smith, Cat number H0610 at Altronics, and HH8510 at Jaycar). These will keep the leaves away. You can also spray the transistor's outer case with circuit board lacquer or something similar for added protection.


See also page 6 & 7 of this thread http://www.fordforums.com.au/showth...05&page=6&pp=25
__________________

for the life of me I cant find this dang fan speed controller.
had the glove box out and cant find no silver metallic box to unscrew.

I have an 03 BA falcon.

any help would be much appreciated

[aussiblue]

BA onward is different the fan speed controller is integrated into the HIM (HVAC Integrated Module).

[mwoonkey]

Damn. Thanks blue

[aussiblue]

See http://www.fordforums.com.au/showthr...56#post5302456

We now know there are two different types of fan speed controller; the more common (and more frequently failing ones) with the TO-3 Motorola transistor and seeming less common and less troublesome (no case in the vent to corrode) Bosch Blower Module ones. I suspect they are interchangeable but someone will have to trial test and see.

[aussiblue]

Also see http://www.fordforums.com.au/showthread.php?t=11433274 re the other small MJE 3055T transistor that also fails.

[Ismegordo]

Originally Posted by aussiblue

See http://www.fordforums.com.au/showthr...56#post5302456

We now know there are two different types of fan speed controller; the more common (and more frequently failing ones) with the TO-3 Motorola transistor and seeming less common and less troublesome (no case in the vent to corrode) Bosch Blower Module ones. I suspect they are interchangeable but someone will have to trial test and see.

Hey there AussieBlue,
Now I am not sure if I have the right part as the part I have seen is the same Silver box and it still gets screwed to the A/C duct work BUT there is no Transistor to worry about, so if thats the one then I can tell you that they are not interchangeable, YES all the Electrical connectors are the same as our one BUT when connected all I got was the Blower only working on H but it would turn off which was at least nice.
I hope this helps and doesn't confuse anyone
Thanks for All your help though AussieBlue.
Regards
Gordon

[MercurySilver]

Lovely
Just grabbed an ef monty wagon and the clinate just stays on at 19 degrees.....wbich is fine right now as its stinking hot.
Ill g et to jaycar and get these parts before xmas

[aussiblue]

Now I am not sure if I have the right part as the part I have seen is the same Silver box and it still gets screwed to the A/C duct work BUT there is no Transistor to worry about, so if thats the one then I can tell you that they are not interchangeable, YES all the Electrical connectors are the same as our one BUT when connected all I got was the Blower only working on H but it would turn off which was at least nice.

Useful to know.

[MercurySilver]

Aussieblue
Ive removed the silver thing via the 3 screws
Prised the tabs open and taken cover off
Thers no transistor in side
Two small circuit type boards. Its pretty clean
In the photos on the prev page you can see the rusted silver cover because of the angle bracket on the bottom, but i have none of that stuff on top like in the photo...unless its all sitting inside the big black box on the right where the silver box inserts
Damn thats a tight fit
??

95 ef fairmont wags
Any ideas?

Would i need to replace the whole silver box bit??

Was the old stuck on 19 degrees no wipers radio power windows etc trick

[aussiblue]

See http://www.fordforums.com.au/showthread.php?t=11433274

[Lastofthev8s]

Thanks to everyone above for helping me solve my problem

My fan was either on high or low, none of the manual settings in between would work

After finding the fan speed control box I removed then replaced only for the fan to work at all times on high even with no key inserted

Found this thread and went to Jaycar. I bought 2 transistors and a pack of insulators for $9

I found it best to unsolder all 3 wires including earth to the bolt for fitment

Using both the insulator gasket and heat sink paste I bolted the transistor to the housing. Then soldered the 3 wires back to their terminals

I now have the full manual range of fan speeds on my climate control for the first time since buying my car

Ford forums is awesome

Thanks everyone again

Black 92 EBII Fairmont Ghia 5.0 full Tickford optioned

[glennrachridd]

2000 AU2 Fairmont. hi guys i have a almost a same problem . my fan for my ac/ heater wont turn off and is stuck on high speed but will turn off with the key off . now after reading alot of pages of stuff on the net i found out how to unplug it so its not going all the time and that i there is a controller behind the glove box so i pulled the unit out and took it auto sparky for to have a look at it and test it they sent it to Melbourne to be repaired $528 later thinking that was the problem plug it back in and still the same . not sure what to do now has anyone had this problem and know whats going on ..... thanks Glen

[pparbo]

1991 EB Fairmont.
My problem is similar to glennrachridd.
I put a new Transistor into the Fan Controller - No good, still the same problem.
I replaced the Climate Control Unit (CCU)- still no good!
WTF is going on??
Is it possible that The Fan Controller is 'stuffed' - Not the Transistor??