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03-11-2005, 01:39 AM
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#1 |
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Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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All or Nothing Fan?
Hey guys!
My 74 just developed an interesting problem this morning. The fan does not come on at all when you just turn on the key, and setting it to medium does nothing as well, but if you set it to high it goes like crazy. Anyone know what I should be looking into as far as fixing it goes?
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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03-11-2005, 01:50 AM
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#2 |
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Right turn Clyde
Join Date: Nov 2002
Location: Cincinnati, Ohio
Posts: 2,911
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Blower motor fan? Clutch fan?
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1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI |
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03-11-2005, 02:32 AM
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#3 |
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Project 2 Resume
Join Date: May 2004
Location: Jim Thorpe, PA
Posts: 884
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if it's the heater/ac blower switch pull the switch and check the positions with an ohm meter.
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John 1984 C30 Chevy Crew Cab Dually 1998 Jeep Cherokee 4x4 2004 Chevy Trailblazer 4x4 (wife's) 1970 Mustang FB fully tubed (getting 521 BBF & powerglide) 1978 Nova 2dr (going BBCaddy & S.P. th400) 1984 Monte SS (circle track car) |
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03-11-2005, 07:42 AM
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#4 |
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Senior Member
Join Date: Mar 2003
Posts: 2,499
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Yeah......what John said,
The high setting is a different circuit than the lower-speed settings so they don't usually go out at the same time. |
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03-11-2005, 10:15 AM
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#5 |
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North Coast, baby!
Join Date: Jun 2004
Location: Toledo, OH
Posts: 437
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My old 76 did the same thing Russell and it was the switch. There's only a few more days until Spring so who needs heat anyhow?
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Brad 79 Scottsdale C20  350/350 3.73's Still running full CA smog gear! 
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03-11-2005, 10:35 AM
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#6 |
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What can I do next ????
Join Date: Jan 2005
Location: Birmingham, Alabama 35126
Posts: 59
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check the blower motor resistor
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03-11-2005, 10:51 AM
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#7 |
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Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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Alright, thanks guys. I'll check the switch this afternoon. I gotta fix it cause today is the last day that I own the 74
 As of 4:00 this evening, it will officially be registered and insured by the guy I am selling it to.
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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03-11-2005, 12:13 PM
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#8 |
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Stepsides RULE
Join Date: Jul 2004
Location: Pineville, LA
Posts: 1,921
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yeah mine is opposite, all positions work except all the way up
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1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord |
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03-11-2005, 12:40 PM
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#9 |
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Happy to be here
 
Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,021
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My guess is the switch as well. In the lower settings you normally have resistance to control the speed. On high speed you have direct voltage...
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Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra" |
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03-12-2005, 07:10 PM
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#10 |
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Registered User
Join Date: Dec 2004
Location: New Lenox, IL
Posts: 442
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Blower Relay? It does make seperate contacts for low/med and high.
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03-12-2005, 10:11 PM
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#11 |
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State of Confusion!
 
Join Date: Jul 2002
Location: Gulfport, MS USA
Posts: 47,226
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I've never had a switch go on my heater-A/C switches, but also the little springie resistor thingie. It's cheap and normally easy to get to.
Never mind I just remembered your thread in new section and looked at date. Bye Bye 74....
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! Last edited by Palf70Step; 03-12-2005 at 10:13 PM. Reason: I'm an idiot... |
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03-13-2005, 02:01 AM
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#12 |
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OutOfMyMind & I'llNeverKnowWhy
Join Date: Apr 2004
Location: Another world, some other time
Posts: 672
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Mine did the opposite and it was the relay on the blowerbox. $10 at autozone.
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-Justin-Out of my mind and I'll never know why 1976 Chevrolet Silverado C10 350 4bbl / TH350 Big10 longbed 1986 Pontiac Firebird T-Top 5.0L TPI 700R4 WS6 1992 Pontiac Firebird T-Top 5.0L TBI 700R4 My cardomain page  I don't like to save, it's more fun to spend!! |
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03-13-2005, 02:10 AM
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#13 |
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Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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It wound up that the connection to the resistors was bad, cleaned the contacts up and I had a full range of fan speeds again
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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