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Cadillac Fan Control Filter Assembly

Dave in Texas on Mon May 26, 2008 10:09 AM User is offlineView users profile

Year: 1987
Make: Cadillac
Model: Coupe DeVille
Engine Size: 4100
Refrigerant Type: 134 conversion
Ambient Temp: na
Pressure Low: na
Pressure High: na
Country of Origin: United States

Does anyone know what the function of the FCFA is? This electrical unit is between the fan-control relay and the fan-control module with 14G wire In/Out. The schematic symbol in the SM shows this piece to be a solenoid but....?! I can not find any info on this unit anywhere. I've asked in various tech groups, but no responses. ACDelco parts guys have no info on it. I'm trying to chase down a pita telltale light problem that's be ongoing for a very long time and I 'wonder' if this piece is or is contributing to the problem. Problem: 'Coolant/Fan Temp' telltale illuminates Only in AC mode and vehicle is idling or moving slowly. Once 35-40mph is achieved, light goes Off. This never illuminates in Econ mode. I've chased the grounds and gone throught the F41 code diagnostic tree, but those procedures showed no problems. There is not a problem in the cooling system, the parameters show it's never been over 220dg since I changed the battery three years ago. Filter? Filter what? It filters the signal from the relay to the module? How does a solenoid filter anything....? I'm stumped. Any ideas/help will be appreciated. I have two SM pics showing this piece, but don't know how to put them on here.....Thanks, I appreciate any info.

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

Dave in Texas on Tue May 27, 2008 9:39 AM User is offlineView users profile

Ok, found out what that part does: electrical noise filter. Was not the cause of problem, unfortunately. Need cooling-fan module, hopefully I can find a good used one somewhere, because I sure can not afford new. Thanks

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

bohica2xo on Tue May 27, 2008 12:17 PM User is offline

Dave:

First, do your fans work? Pull the plugs on the passenger side of the module, and feed one plug 12v & ground. One fan should run. Then try the second one.

I have pulled more than one of those modules from junked cars, and they are still good parts. Fan motors crap out far more often.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Dave in Texas on Wed May 28, 2008 9:02 AM User is offlineView users profile

I've replaced the primary fan motor. It would not play hook-up directly to battery. I tested the module fan-outputs for voltage. 1v difference between the two, but both under 6v, with the Ign On and then also using the OBD program with the fans commanded to Hi. I found a TSB on this intermittent F41 code problem from 1987. It concerned checking the main Ground and apparently some cars had a wrong module. Mine has the correct part number and I'd already checked that Ground connection. I will continue to look for a good used-module. Pricing on this piece is 'dear'. GM dealers want anywhere from $275 to $375 and online parts stores charge $180/up+shipping. Shipping is anywhere from $8 to $25 for this 20oz piece....thanks for the reply.

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

NickD on Wed May 28, 2008 11:36 AM User is offline

Fans and blowers are confusing, fans cool the radiator/condenser, and the blower motor blows air into the vehicle, the blower control module, a solid state device tends to short out leaving the blower run constantly, also has a 30 amp fuse in series with it that never seems to blow first. Your prices tend to make me think you are talking about the blower control module. I did post a repair circuit below someplace where it can be rebuilt better for around 15 bucks.

bohica2xo on Wed May 28, 2008 12:39 PM User is offline

Actually Nick he does mean the radiator fans in this case. GM used the module below to control the speed of the two radiator fans in some Cadillac models. I am sure you could fix his bad one, they are not even potted & the cover is bolted on.







B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Dave in Texas on Wed May 28, 2008 1:48 PM User is offlineView users profile

The innards of that thing are foreign territory for me..

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

mk378 on Wed May 28, 2008 3:16 PM User is offline

One thing you can try is resoldering all the connections on the board. Use a small soldering iron and rosin-core electronic solder. Especially concentrate on the connections to the plugs and the larger, heavier components. The vibration of a car will crack the solder sometimes.

NickD on Wed May 28, 2008 4:58 PM User is offline

Agree with the soldering as long as no burnt parts are showing, found many flux connections a bead of flux around the lead that while looking good, is not making contact to the land of the printed circuit broad. Touch it with a hot iron and you will see a puff of smoke emit. This is caused by either rushing hand soldering or over the wave soldering machine, got to get those products out, quick.

My 92 DeVille went back to relays for fan control so I don't have this module. That MR24D1R is a house number for Delco, order a ton of parts, and they will print anything on it, but is a diode, same with that 16 pin DIP chip, but can also be an ASIC part or a custom if you may. One trick is to grind off the epoxy to the chip and look at it under a 500 power microscope to learn the manufacturer and chip number.

Without the electrical diagram, can't really tell the function of this device, but would get one and check all inputs and outputs first before buying a new one. They don't like taking stuff like this back.

NickD on Thu May 29, 2008 8:49 AM User is offline

Stuff like this always happens, cut down a bunch of trees, hey they are killing each other, go to hook up my trailer to my Caddy, open the trunk to get the trailer cord, pull down motor doesn't come up so I can't close the dang trunk no matter how hard I slam it. One thing at a time, tied it down with a rope, and hauled my trees to the dump. While this is my 5th vehicle with a pull down trunk lid, never had problems with them before until now. Matter of fact, never liked this feature as people were always slamming the trunk down that can break the pull down motor assembly.

So I had to learn how it works, not too bad, close the lid switch then depress the motor switch at the bottom and the striker should go down, raise the motor switch and it should come up, wasn't doing that so pulled both the lid switch and motor assembly on put those on the bench, lid switch was good as was the solenoid, but cleaned the contacts anyway. Problem turned out to be in the reversing switch not providing a ground, brushes and lube of the motor were fine. Really didn't want to take this switch apart, all riveted together so got on the net, have to buy the entire motor assembly for $220.00 with shipping, never called my dealer, they ain't selling cars now, so really sticking it to me on parts costs. That was motivation to drill out the rivets, just drilled out one and learned a perfect hole size for a 4-40 tap, least I can get it back together again.

A tricky switch to put back together with that toggle and spring, but found dried grease that cause high resistance that melted around a plastic embedded switch contact causing the slide armature to raise just enough. Cleaned that off, polished all the contacts, tapped the holes and put it back together again, it works. So just a simple contact problem and can use that 220 bucks to buy 50 gallons of gas. Last month it was the blower control module with also a very steep price tag, didn't like the bipolar design, pass transistor would blow before the fuse, so redesigned that using P-channel FET's with a 430 amp surge capacity. My Caddy as in nice condition as it is, is only worth 500 bucks on a trade-in.

So I can appreciate your problem and these things will overheat without radiator fans. Sure a bunch of electronic crap in these cars, all nickel and dime stuff, until you go to your dealer, least my education is paying off, a little.

Dave in Texas on Thu May 29, 2008 10:24 AM User is offlineView users profile

I've replaced the Primary fan-motor and will replace the module as soon as it arrives. Next up is to cure one/more oil leaks on this vehicle. I'm fairly-certain I can get to the offending gaskets/seals from the RH wheel-well. Not much of a fun job for me since I have a single-car garage and have to do it in the driveway/90dg+days/no shade/old-timer/not rich enough to hire the job out, but WTH! I'll just do it. Next life I'll choose rich instead of good-lookin'. Thanks

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

NickD on Thu May 29, 2008 12:01 PM User is offline

That PCB has all the signs of being hand assembled and soldered, either in Mexico or China. For automatic insertion and wave soldering, the leads are straight and all cut to an even length with a router and the flux is burnt off completely. Try touching any lead with a hot soldering iron to see if you get a puff of smoke, dead give away. Use only 60/40 rosin core solder for touching up. Dang stuff today is like buying gold.

Dave in Texas on Sat May 31, 2008 8:45 AM User is offlineView users profile

Replaced module yesterday. This module cured the F41 code/telltale light problems. Next is the gasket replacement project.
If anyone has experience on replacing the gaskets on this FWD Cad: does a 'conversion set' of gaskets contain every seal/gasket needed? Also: can the oil-pan gasket be changed with the engine still mounted in the cradle?
Thanks Brad for the help!

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

NickD on Sat May 31, 2008 9:58 AM User is offline

Ha, back in the 50's could buy a complete overhaul gasket set that contained everything you needed plus a lot of stuff you didn't need, like two sets of head gaskets that covered both smaller and larger V-8 GM engines or two sets of valve seals. Had to keep track of the gaskets you were taking out and line those up, but still had enough gaskets left over to do another engine. Price back then was four bucks for the entire set. Use to pull engines apart just to clean them and install new gaskets, made a huge difference.

According to my 92 shop manual, you can just drop the pan, remove negative battery cable, raise engine, drain oil, remove two flywheel covers, pan bolts and drop pan. They seem to be fussy about adding RTV to key spots around the front and rear main bearings, I like to RTV the entire gasket. Gets a little tight around the timing chain cover, and if your car is like mine, those AC lines are sure in the way. So do your fans work now?

Dave in Texas on Sat May 31, 2008 1:37 PM User is offlineView users profile

I would have done this a long time ago had the engine been installed properly in the first place. Someone put it in sideways! I'll scope-it out, clean everything up, check for loose fasterners and see after that. I used to work at a parts house 40yrs ago, but stuff changes over time when it comes to wording. Thanks Nick

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

NickD on Sat May 31, 2008 4:04 PM User is offline

See that rockauto.com wants 230 bucks for a "Complete gasket set" less exhaust packing, prices have gone up. Had to pay over nine bucks for a rear end gasket and 27 bucks for upper intake manifold gaskets, pretty expensive pieces of paper, where's the gold?

Yeah, I thought I was crazy for buying a V-8 in a FWD, but my Caddy is not too bad for changing the rear plugs, have to remove the strut tower brace and the relay box first. But getting to the block coolant drain plug is impossible with that transaxle only an inch away from it.

Dave in Texas on Sun June 01, 2008 12:54 PM User is offlineView users profile

Yeah, getting to the plugs on the rear-bank is a challange. I was able to change them by jamming my arm down to each. I installed some fancy platinums, so they should out-last me. Somewhere I heard or read these transverse-mounted engines can be 'rolled' to get access to that area, but I haven't a clue about the procedure. Thanks Nick

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

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