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Topic: Heat/A/C fan speed

in Forum: C3 Cooling and Heating Systems

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Heat/A/C fan speed (1/14)
7/21/08 4:50pm

Brown78
Former Member
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Ft.Lauderdale, FL - USA

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.

Joined: 6/21/2008
Posts: 31

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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Heat/A/C fan speed (2/14)
7/21/08 6:27pm

DaveM

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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.

Joined: 1/27/2004
Posts: 2553

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.

Dave

DaveM2008-07-21 18:29:39

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Dave's '82

Heat/A/C fan speed (3/14)
7/22/08 7:59am

gs77vet
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Joined: 3/19/2005
Posts: 385

Hi speed has a fuse seperate (on my 77) from the other speeds. It is the top fuse in the fuse box. I use a fuse with a circuit breaker, I buy the fuses at NAPA, 30 amp. Gene

Heat/A/C fan speed (4/14)
7/22/08 10:16am

Adams' Apple

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Duncanville, TX - USA

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

Joined: 11/8/2003
Posts: 20210

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.

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Heat/A/C fan speed (5/14)
7/27/08 7:03am

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.

Heat/A/C fan speed (6/14)
7/27/08 7:37am

Adams' Apple

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.

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Heat/A/C fan speed (7/14)
7/28/08 7:44am

DaveM

My money is still on the resistor.

Dave

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Dave's '82

Heat/A/C fan speed (8/14)
8/3/08 8:13pm

gemini
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Vette(s):
04 57 80corvette/berlina

Joined: 5/31/2008
Posts: 6

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

Heat/A/C fan speed (9/14)
8/4/08 4:36pm

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. Embarrassed

How can I test if the link is bad? Brown782008-08-04 16:36:59

Heat/A/C fan speed (10/14)
8/4/08 6:06pm

gemini
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Vette(s):
04 57 80corvette/berlina

Joined: 5/31/2008
Posts: 6

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!!!

Heat/A/C fan speed (11/14)
8/4/08 7:10pm

Adams' Apple

[QUOTE=Brown78] 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. Embarrassed

How can I test if the link is bad? [/QUOTE]

Sooooo....what yer sayin is...you HAD high speed until ya messed with the wires on da relay?

The high speed is controlled by that relay...might wanna check yer work again!

(just messin with ya

)
There is usually a fuse-link for the blower motor running in the harness, just to the passenger side of the distributor area. But...you had high before, so I can't see the fuse-link being a problem. Most of the time, when the high speed doesn't work, it's the relay.

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Heat/A/C fan speed (12/14)
8/5/08 11:26am

gs77vet
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Joined: 3/19/2005
Posts: 385

The fuse was my problem, I put a circuit breaker fuse in (30amp)and it has been working since.
BUT, in order to get my blower to work I have to slide the heat wide open for a couple of seconds, pull to slide back to the correct position and the blower works fine. WHY?
Gene

Heat/A/C fan speed (13/14)
8/19/08 9:01pm

gemini
Former Member
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Vette(s):
04 57 80corvette/berlina

Joined: 5/31/2008
Posts: 6

all

i changed the rear springs to trw composites and upgraded the front springs with kyb g2 and presto the ride improved a lot

this of course is true as long as your on a decent road

if you get on one thats choppy at all you can still feel the hard ride

overall its great improvment!

thanks again for all the info!! it worked

now to find electric sports mirrors for the 80 s wonder if c4s can work??

Heat/A/C fan speed (14/14)
8/20/08 6:47pm

kstyer

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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!

Joined: 12/2/2003
Posts: 6424

Gs77vet

The heater control head also has a switch for blower control. It only allows the blower to run on low when the heater control head is shut off. But you switch is starting to fail, or has dirty contacts. Either way, it may continue to work that way for years, or may fail soon. You will need to replace/repair the heater control head.

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