Topic: Heat/A/C fan speed
in Forum: C3 Cooling and Heating Systems
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Ft.Lauderdale, FL - USA
Joined: 6/21/2008
Posts: 31
Vette(s): 78 coupe, Dk Brown, ZZ4 385 hp fast burn, steeroid rack/pinion, Keisler 5 speed. Built to run with C5 and C6. on the highway. Can't beat them. But they can't lose me in there mirrors. LOL I built it to enjoy. So far I've tripped through 15 States.
I only have one speed on my fan control. I have a new 3 speed switch to put in. Question is will this get me low, mid, hi fan speeds??? Or is there another elect. relay for the fan some where else?
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There is a resistor assembly in the engine bay on my '82. There is a plate on top of the blower housing with a connector, unplug the connector and remove the plate and the resistor assy is mounted on the inside of the plate. This is most likely your problem. The high speed setting does not use the resistor, so when the resistor goes bad you loose low & medium speeds but not high speed. simple fix, takes 2 minutes.
DaveM 2008-07-21 18:29:39
Dave
Lifetime Member #116
Dave's '82 
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
What speed(s) do you have now? Low? Med? High?
The others are correct. High speed is a totally separate circuit, and runs from a relay, usually located on the side of the A/C plenum(box) in the engine compartment. There will also be a separate fuse for this circuit.
The other speeds are regulated by the aforementioned resistor assy., located as Dave stated on the top of the plenum.
If you have only high speed, check the blower-A/C fuse first in the fuse box. Then go to the resistor block next. Sometimes, the resistor assy just gets a little rusty, and a little tap might get it making contact again....until it happens again.
The resistor is really just a series of coiled wires, with each coils series a different speed.
The others are correct. High speed is a totally separate circuit, and runs from a relay, usually located on the side of the A/C plenum(box) in the engine compartment. There will also be a separate fuse for this circuit.
The other speeds are regulated by the aforementioned resistor assy., located as Dave stated on the top of the plenum.
If you have only high speed, check the blower-A/C fuse first in the fuse box. Then go to the resistor block next. Sometimes, the resistor assy just gets a little rusty, and a little tap might get it making contact again....until it happens again.
The resistor is really just a series of coiled wires, with each coils series a different speed.
Joel Adams
C3VR Lifetime Member #56 
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Former Member
Send PM
Ft.Lauderdale, FL - USA
Joined: 6/21/2008
Posts: 31
Vette(s): 78 coupe, Dk Brown, ZZ4 385 hp fast burn, steeroid rack/pinion, Keisler 5 speed. Built to run with C5 and C6. on the highway. Can't beat them. But they can't lose me in there mirrors. LOL I built it to enjoy. So far I've tripped through 15 States.
I only have high speed. I removed the resister and cleaned it up on the wire wheel. Still only one speed " high". Today I'm going to check the fuse block.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
If the fuse is good, then you'd need to go to the switch, which you say you have a new one for. Make sure to check for 12v(key on) at the connector first, tho. 
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
hey guys
i think my fan goes to med not high its been a while since i have had a c3 so i m a little rusty
i thought i used to get some real air out of my fan on high but i dont get a lot
its a low mile car with AC 30k and the fan is really quiet
i cant get the ac to cool down the car without a lot fan speed to circulate it
could i have the fan working on lower speeds except high?? and i have high just not working??
also i have rattles and sqeaks comining out of the center of the dash
thinking its the ac stuff behind the panel
any suggestions on how to muzzle the noise??/ thanks
Former Member
Send PM
Ft.Lauderdale, FL - USA
Joined: 6/21/2008
Posts: 31
Vette(s): 78 coupe, Dk Brown, ZZ4 385 hp fast burn, steeroid rack/pinion, Keisler 5 speed. Built to run with C5 and C6. on the highway. Can't beat them. But they can't lose me in there mirrors. LOL I built it to enjoy. So far I've tripped through 15 States.
I installed a new resister and corrected the 3 bottom wires connection on the relay. Now I have low and mid no high speed. I asked around and was told that there is a fuse-able link somewhere between the fuse block and the relay. If this is true. I can't find it. The only fuse-able links I can find is connected to the starter. I thought there would be only 1 kink but, there was 2. Where do they go to. 
How can I test if the link is bad? Brown78 2008-08-04 16:36:59
How can I test if the link is bad? you guys really really rock
i followed up on your suggestions and presto......and i got my high fan working with the fuse
now any ideas on the rattles and sqeaks inside the ac central panel??
its really annoying
maybe when i get my new front springs and composite rears with new shocks its going to make for a much softer ride! and less rattles!!!
in Forum: C3 Cooling and Heating Systems
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