Topic: AC fan problem
in Forum: C3 Cooling and Heating Systems
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Some of our cars have a hot lead directly from a fusiable link to the high position on the blower relay. Some are fused or use a circit breaker. If you have a high speed blower relay, the relay uses the switch to control the lower speeds through the resistor block, and uses a separate power supply to the relay to supply direct power through the relay to the blower motor for high speed. In this case the high speed switch on the dash supplies power to trigger the relay when you select high blower.kstyer 38920.8302430556
Lifetime MemberPoquoson, VA - USA
Joined: 11/20/2004
Posts: 1023
Vette(s): 73 Conv, Blue-Green/White Top - 454, M21 - Dark Saddle Leather, Power Windows, A/C, Tilt/Tele, AM/FM St. (orig. and sounds like it too).#2 -- 2007 Coupe,3 LT package, Z51 option, Victory Red, Ebony Int. Clear Top.
[QUOTE=annicorvette]Do you have a rear defrost ? if you do check this--in my 78 the fan is wired so the high speed fan is disabled if the rear defrost is on. Don't ask why i just know it is.[/QUOTE]
Is it possible they use the same circuit and if both are on high the AMP draw would be too high?
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USN 1966-1970
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Featured in Corvette Enthusiast Aug 2007 "Shark Attack"
Blue Green *** 454,4 Spd, Dark Saddle Leather, A/C, AM-FM St. (orig), PW, Tilt -Tele Wheel"
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USN 1966-1970
WestPac 67-68 Tet I&II
Featured in Corvette Enthusiast Aug 2007 "Shark Attack"
Blue Green *** 454,4 Spd, Dark Saddle Leather, A/C, AM-FM St. (orig), PW, Tilt -Tele Wheel"
(click to see a bigger image)
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Duncanville, TX - USA
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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
More than likely. 
It should be noted tho, that on the '74(and earlier cars, up to '77), the rear defrogger was simply an extra blower fan that blew on the rear winder. The later cars('78-82) wid da large rear winder had imbedded defrogger circuits in the glass.
The 'lectric defroggers take quite a bit-o-'lectristity, which is why they are almost always on a timer.
Adams' Apple 38951.7151273148
It should be noted tho, that on the '74(and earlier cars, up to '77), the rear defrogger was simply an extra blower fan that blew on the rear winder. The later cars('78-82) wid da large rear winder had imbedded defrogger circuits in the glass.
The 'lectric defroggers take quite a bit-o-'lectristity, which is why they are almost always on a timer.
Joel Adams
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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
That could be the blower switch, or the resistor bad. It could also simply be a fuse.
On most cars, the high speed blower is on a completely different circuit. This is why most of the time, it is the high speed that doesn't work, but the low speeds do. But, the other way happens also. I would start by checking fuses, and then the switch.
On most cars, the high speed blower is on a completely different circuit. This is why most of the time, it is the high speed that doesn't work, but the low speeds do. But, the other way happens also. I would start by checking fuses, and then the switch.
Joel Adams
C3VR Lifetime Member #56
My Link
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
It works !
I had the car out for a ride the other day, started to play around with the A/C Heater controllers and everything works 
. I've gone crazy trying to figure this problem out, and low and behold, it's working 
.
. I've gone crazy trying to figure this problem out, and low and behold, it's working . Hey, at least it's working, now if it will work in the summer is another question.
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
Now...you know the first time you need that high speed blower with the A/C on, it ain't gonna work!!
Sounds like you may just have a bad connection somewhere, or one of the micro-switches in the control unit(thumbwheels). Hey, as long as it works, eh?
Sounds like you may just have a bad connection somewhere, or one of the micro-switches in the control unit(thumbwheels). Hey, as long as it works, eh?
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"
in Forum: C3 Cooling and Heating Systems
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