Topic: Correct fuse amperage for Heater / AC blower, High Speed
in Forum: C3 Electrical
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Does anyone know the correct fuse size, (amperage) that goes in the fuse link on the orange wire, that operates the high speed setting on the heater blower switch?
This is the orange wire with the fuse link that runs over to the passenger side to the high speed blower relay, (1975 Corvette).
My fan doesn't blow on high. I pulled the fuse and it's old, rusty and blown. However, I can't read the amperage on the old rusty fuse and I don't want to try replacng it unless i have the correct amperage, (don't want to melt any wires).
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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
I think they are 30 amp, but I need to look in the manual to be sure.
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"
Adams' Apple said: I think they are 30 amp, but I need to look in the manual to be sure.
What manual are you referencing? I looked through the owners manual as well as my Haynes manual,..but I can't find the info anywhere.
I am always very scared about having a wiring melt down. To me, wiring can be the biggest headache,..not to mention fire concerns.
Please let me know if you can confirm.
Thanks!!!
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
According to the Service Manual, and the wiring diagram, 25 amp fuse in the fuse box, and 30 amp in the in-line fuse holder. 
btw..if the fuse holder is rusty/corroded, be sure to clean both ends of it really well, or replace it. Rust, or any kind of corrosion can create high heat with a lot of current flowing, which could melt the plastic holder, or keep the fan from blowing properly.
|UPDATED|7/19/2013 7:48:19 PM (AZT)|/UPDATED|
I use both the Factory Service Manual, and Mitchell Vintage to get a lot of this kind of info. The Haynes/Chilton type manuals don't always go into very much detail on accessories like the A/C system, nor does the Owner's Manual normally have fuse-link, or in-line fuse info.
|UPDATED|7/19/2013 7:48:19 PM (AZT)|/UPDATED|
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"
Thanks for the info!!! I appreciate the help.
Yes,..the old fuse was actually rusted inside the holder. Both ends of the wiring tips were rusty too. (how did it rust inside the fuse holder)? I have cleaned both ends up with a steel wool pad. They look good now.
I will probabaly put a little dab of dialectrical grease on each end when I replace the fuse.
Thanks again!!
Rust, or any kind of corrosion can create high heat with a lot of current flowing, which could melt the plastic holder, or keep the fan from blowing properly. Or causing a fire that burns your car to the ground!
I suggest that you not use that crappy old fuse holder. On my '73 I soldered in a modern style fuse holder.
John
1973 BB 4-Speed Coupe Project Car
2009 Z06 Mostly Stock
The amp rating should be noted on the fuse box if it still can be read. I just had my c3 completedly rewired New fuse box and all new wires to all controls and lights. along with new A/C unit and wiring harness . This was due to a short in console which melted the wiring harness next to the tran neutral switch .Being 43 years old beware you could be next , so how old are your wires? The cost as of today over $4000,00. Which i was lucky the insurance payed cause i called it a fire. If it had been turned in as corrided wires they or anything due to age ,i checked my policy first before filing claim to Haggertys.This is very important to read and know your policy.I didnt have $4000.00 to pay for this, would you?
in Forum: C3 Electrical
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