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'71 Fan Switch

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
I have a '71, base motor, Automatic, PS, PB and A/C.
Problem #1
I am having issues with the fan motor switch on the console: It seems to have only one speed (low) no matter where I position the switch, so it doesn't really cool the car down. It is also difficult to move the switch lever. More troubling is the switch lever becomes so hot that you can barely touch the thing without burning your fingers. I'm afraid the damn thing is going to set the car on fire ! Any ideas ?
Problem #2
The transmission leaks fluid. Sometimes it seems to leak a lot, other times not so much. I took it to a local shop and asked them to fix the leak. They pulled the pan, installed a new gasket - it still leaks. I then re-tightened the pan bolts as they seemed to loose to me - it still leaks. Some have suggested i replace the pan itself with another new gasket. I can easily do this but if it still leaks i will be very unhappy. Any suggestions will be appreciated.

I am trying to sell this car and buy a C-6, but feel I have to solve these issues before I list it.
Thanks,
Bernie O
 

bill81vette

Moderator
Joined
Jan 17, 2004
Messages
4,272
Location
Troy,NY
Corvette
1981 dark blue metallic
1st.fan switch...check you fuse make sure it hasn't corroded.
Otherwise you switch is most likely going bad.
2nd tranny leak chances are you pan bolts have overtightened and are no longer even with the pans surface they probably have been pushed up a little and it is having a hard time sealing.remove the pan again and you'll probably have to have the bolt holes flattened back down.

Sent from my moto z3 using Tapatalk
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
Bill,
Thanks for the response !
Fan Switch: I probably should have noted that this is the 3rd or 4th fan switch I've installed in this car. The've all had the same problem except the original that I replaced when it "died". One of them actually looked like it was burned and about to catch fire. I pulled the inline fuse from the wire in the engine compartment and it looked like there might be a little corrosioin on the inside of the fuse. I'll just go ahead and replace that as well as the one in the fuse panel. I still dont understand was this switch is so hard to move from one position to the next. I'm also not enough of an electrician to test the switch with a meter to see what, if anything, that would tell.

Trans Leak: Yeah, you pretty much said what a few others have told me. I may just buy a new pan and gasket and be done with it .
Thanks for the help !
Bernie O
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
Bill,
I replaced both the underhood and under dash fuses yesterday; both were somewhat corroded with the under dash fuse being worse. There is definitely improvement, but the fan still does not seem to have the "high" speed. Any thoughts ?
I'm going to order a new trans pan and gasket soon and will let you know how that goes.
Thanks again,

Bernie O
 

bill81vette

Moderator
Joined
Jan 17, 2004
Messages
4,272
Location
Troy,NY
Corvette
1981 dark blue metallic
check the blower motor.remove it and try it with a couple of jumper wires to a battery to see how well it works
check in where the blower sit and make sure the critters haven't made a home in there.
check your grounds to make sure they are good.
good luck!!!
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
Fan speed resister is burnt out,It's in the AC case under the hood held in with 2-3 screws and has 3-4 wire plug on it.:thumb

Trans leak is probly dipstick tube seal,Longer it sets,More it will leak as the fluid comes down out of the converter and rises the fluid level setting. Common on Turbo 350 and 400's.:beer
 

Tom Bryant

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Administrator
Joined
Nov 9, 2000
Messages
7,205
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
I agree. The resistor has coils of different gage wire that control the motor speed. If one coil burns out you loose that speed.
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
Ok ….. I like the idea that its the resistor. However, I'm looking through the Corvette Central catalog and I see P/N 453048 for an "A/C Blower Motor Resistor" for a '68 and P/N 453044 for an "A/C Blower Motor Resistor (on top of A/C box)" for a '72 - '82, but nothing for '69 through '71 ??? On top of that I just went out to see if there was one on my A/C box. There is a bright aluminum thing that looks more like a horn relay ("A/C Blower Motor Cutout Relay" ??) and looks almost new. On top of that the thing is warm, almost hot, to the touch. That's not right is it ? I disconnected the battery when i found that out !
I've had this car for almost 12 years and I never replaced this resistor or relay or whatever it is, but it may have been replaced when I had someone do the A/C change over from R-12 to R-134a a couple of years ago.
Thanks for any and all thoughts and suggestions !
 

Tom Bryant

Well-known member
Administrator
Joined
Nov 9, 2000
Messages
7,205
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
On my '81 this inserts right on top of the a/c evap /heater box. Has a plug on it. Here is one for your car from Zip. Original GM part number was 3942651. You can just remove the 2 screws and pull it out to look at it. It will be easy to tell if one of the coils is burnt out.


Resistor

Tom
 

DGVETTE

Well-known member
Joined
Jan 7, 2008
Messages
52
Location
Marion, AR
Corvette
2004 Coupe, 1971 Coupe
Corvette Central Part #453179 69-71 Air Conditioning Resister - On Top Of AC Box For Blower Motor
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
DG, Thanks for the part number. I must need a new catalog, because this P/N is not in my book. The other thing is I cannot see this thing anywhere on my car. There is something that looks more like a horn relay on the side of the A/C box toward the engine, but I think that's the Blower Motor Cutout Relay. Any chance anyone has a picture of this on their car ?
Thanks for all the help !
 

DGVETTE

Well-known member
Joined
Jan 7, 2008
Messages
52
Location
Marion, AR
Corvette
2004 Coupe, 1971 Coupe
No Picture. Switch is physically located below the outside mounting bolt for windshield wiper door vacuum actuator. The resistor assembly is located inside the AC box and only the wiring connector is visible outside the box. It is a 4 wire connector: purple (mine looks dark blue); light blue; yellow and light green wires according to AIM wiring diagram.
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
DG, Tom,

Thanks ! I thought that might be it. But how do i get the resistor out of there ? Do I just pull on it or do I have to open up the A/C box ? There don't appear to be any screws holding it down.
And while I was fishing around I found this thing all taped up and stuffed under door actuator. What the hell is this ??? It is definitely still hot as I could read 4 - 6 Volts on it with a meter. A little scary if you ask me.
Thanks again for all your help - you guys are great !
Bernie O

IMG_3315.JPG
 

DGVETTE

Well-known member
Joined
Jan 7, 2008
Messages
52
Location
Marion, AR
Corvette
2004 Coupe, 1971 Coupe
i have not removed resistor before, but mine appears to have 2 bolts mounting it to AC box. WW Door Actuator will probably have to be removed to gain access room.
The picture is a mystery to me. I don't see any wires similar to those (color) on my car in that area.
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
OK, now I'm really at a loss. I finally figured out how to get the resistor out: One screw was hidden under the ww actuator door and a wiring harness clip and the other screw was hidden under what I can only describe as dried out and/or melted plastic or caulk. I had to chip away at it with a screw driver and putty knife to expose the second screw.
Soooo..... I pull the resistor out and it appears to be fine. Now what ? I've got a new resistor ordered (fairly cheap) so I might as well install it along with the Blower Motor Cutout Relay that I ordered as well.
I'm still concerned with the wires and melted connector in my earlier post. I don't know what they are or where they go, but I downloaded a wiring diagram that I'll have to study a little bit more to try to make sense of this mess - it's getting really frustrating at this point (my '59 is a LOT easier to work on !)
As always, any and all comments/suggestions are welcome and appreciated !
Thanks,
Bernie O

IMG_3330.JPGIMG_3331.JPG
 

Tom Bryant

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7,205
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
You should have 2 bigger wires on the relay and 2 smaller. One of the bigger is 12 volt with key on and the other goes to the blower motor. Jump across them and see if the motor spins up to full speed. Sounds like you have a short someplace to cause that switch to get that hot. May be related to that melted mess. 3 green wires together makes me think someone has been doing some home brewed fix of some sort.
 

Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
Tom,
Just tobe sure so I don't blow something up or set something on fire: You mean the RELAY that's on the side of the A/C box and NOT the resistor that I just pulled out, correct ?
And I'm still trying to find out what that "melted mess" is; I've got to wait until I can get a friend over here to help me trace it.
Thanks for your help.
 

Tom Bryant

Well-known member
Administrator
Joined
Nov 9, 2000
Messages
7,205
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
Yes I'm talking about jumping the relay. Here is a picture from Wilcox that might help.
 

Attachments

  • 69-71 C3 blower motor relay.jpg
    69-71 C3 blower motor relay.jpg
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Bwmurph

Well-known member
Joined
Dec 24, 2003
Messages
367
Location
Conway, SC
Corvette
'59 Blk/Red, '71 Blk/Red
Tom,
The plot thickens !! Take a look at this: I received my new relay and resistor today and I was going to take your advice and jump the two wires that you suggested to see what, if anything, would happen. So I pull the relay off the A/C box and this is what I find. Someone has positioned the three wire connector so that it is only plugged into one terminal !! On top of that it looks like they've jammed two wires into the same (top) socket (I literally just noticed that when I was attaching these pictures to this email). I'm going to have to double check the wiring diagram because I don't think that all the wires are the correct colors - looks like there are two orange and a dark blue and I think there is supposed to be a green or yellow in this connector somewhere, Again, I'll have to check the diagram.

I don't know what to make of this mess now, but I know its driving me up the wall. I'm hoping this can all be straightened out under the hood, because I really don't want to take the console in this car apart again if at all possible.

And I still have the trans leak to deal with !! That should be a walk in the park after this.


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