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Old 08-29-07, 04:01 AM   #1 (permalink)
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fan control repair (add more solder)

Hi all, thought I’d add a post for those who are suffering with whacky radiator fan & A/C behavior.

Here’s the symptoms I had:

A/C clutch would engage at every start (A/C switch in the off position ! ) for ~ 5 to 10 minutes.
If it was hot and the car restarted after an hour or less, the A/C would not work, no clutch engagement.
The car came to me with a worn out A/C condenser fan.
The rad fans would run at high speed at every start for a few minutes. At times the fans would turn on and off and vary their speed.

So A/C on cool mornings, and no A/C on hot afternoons getting into a parked car… grrrr

The cure, you guessed it, resolder some of the joints on the fan controller board.
I had eyeballed the board previously and it seemed ok, during inspection #2 I got out the magnifier and found about 10 bad solder joints. What I saw were circular cracks in the solder joints on the back of the board. The solder joints are about 1/16” in diameter, the cracks ran around the wire of the attached component and formed circles about 1/3 of the diameter of the solder joint. This left the wire attached to a little cone of solder that had separated form the main part of each affected joint. Presumably these cracks were caused by thermal cycling, perhaps the amount of solder applied was inadequate. In any event I resoldered using a small soldering iron (not a soldering gun) and some fine electronic solder. It seems to work just fine now.

Cheers, Jay
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Old 08-29-07, 10:21 AM   #2 (permalink)
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Quote:
Originally Posted by Jay P View Post
Hi all, thought I’d add a post for those who are suffering with whacky radiator fan & A/C behavior.

Here’s the symptoms I had:

A/C clutch would engage at every start (A/C switch in the off position ! ) for ~ 5 to 10 minutes.
If it was hot and the car restarted after an hour or less, the A/C would not work, no clutch engagement.
The car came to me with a worn out A/C condenser fan.
The rad fans would run at high speed at every start for a few minutes. At times the fans would turn on and off and vary their speed.

So A/C on cool mornings, and no A/C on hot afternoons getting into a parked car… grrrr

The cure, you guessed it, resolder some of the joints on the fan controller board.
I had eyeballed the board previously and it seemed ok, during inspection #2 I got out the magnifier and found about 10 bad solder joints. What I saw were circular cracks in the solder joints on the back of the board. The solder joints are about 1/16” in diameter, the cracks ran around the wire of the attached component and formed circles about 1/3 of the diameter of the solder joint. This left the wire attached to a little cone of solder that had separated form the main part of each affected joint. Presumably these cracks were caused by thermal cycling, perhaps the amount of solder applied was inadequate. In any event I resoldered using a small soldering iron (not a soldering gun) and some fine electronic solder. It seems to work just fine now.

Cheers, Jay

It's amazing what you can find under magnification.

The same repair procedure usually works for the speed sensor in the speeometer head.
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Last edited by paulo57509; 08-29-07 at 02:13 PM.
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Old 08-29-07, 11:44 AM   #3 (permalink)
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Old 08-29-07, 12:21 PM   #4 (permalink)
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Jay, thanks for this posting. I too have intermittent fan problems that are really unexplainable. Most of the time neither fan runs (figured I had a bad sensor, relay or something) but yesterday for some unexplained reason the fans started cycling on and off normally.

So, where is the fan control board? My shop manual shows the fan control unit under the dash. Is that what you're talking about?
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Old 08-29-07, 03:47 PM   #5 (permalink)
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the fcu

FCU does seem like a pretty appropriate abreviation....
yep it's the one under the dash, black box about 3" x 4" way up & under the dash, about 4" to the left of the radio. I used a 10x loupe to see the solder trouble.

cheers, Jay
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Old 08-29-07, 05:11 PM   #6 (permalink)
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Hey Jay, thanks for getting back to me so soon. Now, if you would tell me if this unit is more easily accessible by removing the lower dash panel or by removing the radio I'd appreciate it.

In fact, you've been so kind why don't you come by the house after work and take this thing out for me
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Old 08-29-07, 10:48 PM   #7 (permalink)
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that darn FCU

Hi, you can leave the radio alone for this one, access the FCU by removing the plastic panel below the dash, aka the panel above the driver's feet. Pull the panel, note the metal clip in the center of the panel, closest to the firewall, near the steering column, is released by reaching behind the panel and squeezing the clip that is attached to the panel and protrudes through a 1" x 1/2" hole in a bracket attached to the chassis, maybe that will make more sense once you yank it off and see for yourself.
The FCU is mounted 'vertically' about 2/3 of the way from the column to the radio. What I hate most about it is wriggling awkwardly into position and then discovering I can't reach the 1/4" extension that had rolled under my ass without getting out and then wriggling back in all over again only to realize I have the wrong socket. And then it's time to play 'where the hell did that bolt go'. Kinda makes one wonder, why why why.

I'll come out and declare your FCU unrepairable for a modest fee if you buck up for the airfare!

have fun under the dash, Jay
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Old 08-29-07, 11:17 PM   #8 (permalink)
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Thanks for the detailed description. I've been under my dash too many times just as you described and really didn't want to go through it again.

I think there should be a law prevented auto manufacturers from placing any parts under the dash except a fuse box. And the fuses would have to have proven accessibility while driving the Boston's I-128 at 90, Blackberrying your boss in LA, and drinking a diet Coke while eating a beef jerky. Other than that nothing goes under the dash.

Thanks again!
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Old 10-04-07, 09:38 PM   #9 (permalink)
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so im gonna be taking this FCU out soon, what i was wondering, is it possible to drive without it installed?

mechanic said i needed a new one and i read the resolder repair and thought i'd try that, but idk if the solder guys are still open

i would sure love to be able to drive without the FCU installed for simplicity's sake
thanks
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Old 10-04-07, 09:55 PM   #10 (permalink)
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well i believe i have uninstalled the correct thing, its a little black box (shaped somewhat like an "L", that was held on with one screw which had a 6 prong electrical connector

also the black case had the words "ILLMI controller" and "nippon seiki japan"

i hope this is the fan control unit and I would appreciate any feedback as to if i am correct or not
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Old 10-04-07, 10:22 PM   #11 (permalink)
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I think you've pulled the wrong thing out. I'm looking at mine now (from an 86 and I just put one in from an 88, both the same) and it's 3x3x1 with a connector that's 2 rows of 5. Also, no screws needed to pull it out. It's held in by a bracket and a real bear for me to get out.
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Old 10-05-07, 12:06 AM   #12 (permalink)
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anyone else agree?

i think jgurley is right, that seems like it was too easy to get out lol
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Old 10-05-07, 12:19 AM   #13 (permalink)
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Trust me on this one. I just took another look at mine and it says

Control Unit, Rad Fan
37735-PH7-0030
TV-43
Lot No. 6.3.251

I have no idea what you pulled out. BTW, your car will run without the FCU.
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Old 10-05-07, 01:10 AM   #14 (permalink)
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FCU vs illmi controller

Hi, the Fan CU is outboard of the ill mi controller and a little higher up, the fcu is above the driver's right knee. BTW, what the hell does the ILL MI controller do? TI think I looked briefly at the schematic but didn't find reference to it. Controls the illumination of something? Probably the control box for the ashtray light judging by the rest of the electronic overkill present.

Anyway, keep hunting. The acura electrical repair manual is somewhat helpful as it had photos of the mounting position of most items.

cheers, Jay
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Old 11-01-07, 08:24 PM   #15 (permalink)
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found it

well if anyone else needed to know what the RFC looked like i got some pics



also i have a picture of the contacts, and i needed to know, which of the contacts must be re soldered? is it just all of them or only a certain few?


thanks for any help
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