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Topic: AC fan problem

in Forum: C3 Cooling and Heating Systems


AC fan problem

Posted: 7/9/06 5:22pm Message 1 of 20
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Roseland, NJ - USA
Joined: 12/4/2003
Posts: 966
Vette(s): 1974, 454 with 4 on the floor, matching numbers.

I went over my AC yesterday, held 230 PSI for 20 min. System was cooling great, but my problem is my fan speed won't go into high speed. I have a new control switch, and AC/heater control panel. I had the motor & fan tested (just in case I had to replace them) and  everything worked great. Could my switch gone bad so quick ? Has anyone have any suggestion.

Without the high speed there isn't enough air blowing out to cool the cabin.    

warbird38907.7255671296


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AC fan problem

Posted: 7/9/06 5:31pm Message 2 of 20
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Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
[QUOTE=warbird]

I went over my AC yesterday, held 230 PSI for 20 min. System was cooling great, but my problem is my fan speed won't go into high speed. I have a new control switch, and AC/heater control panel. I had the motor & fan tested (just in case I had to replace them) and  everything worked great. Could my switch gone bad so quick ? Has anyone have any suggestion.

Without the high speed there isn't enough air blowing out to cool the cabin.    

[/QUOTE]

did you check the wire itself for a break.  test it for continuity end to end.

also.. to help the cabin cooling..  have you put a shut off vavle on the heater core?




AC fan problem

Posted: 7/9/06 5:37pm Message 3 of 20
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Roseland, NJ - USA
Joined: 12/4/2003
Posts: 966
Vette(s): 1974, 454 with 4 on the floor, matching numbers.
Yup, did all that. The fan doesn't change speeds no matter were I put the switch.


AC fan problem

Posted: 7/9/06 6:09pm Message 4 of 20
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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
You probably need to replace the fan speed resistor. On the top of the A/C box.


Joel Adams
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AC fan problem

Posted: 7/9/06 8:34pm Message 5 of 20
Former Member
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Roseland, NJ - USA
Joined: 12/4/2003
Posts: 966
Vette(s): 1974, 454 with 4 on the floor, matching numbers.
Joel, the fan speed resistor was tested to see if it got current. However are you suggesting that even if it's receiving current it may still be defective ?


AC fan problem

Posted: 7/9/06 9:07pm Message 6 of 20
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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
It can be getting juice, but is it sending that juice out(back thru the switch)?
Also, you may need to test/check the high-speed relay. It is only used for the high speed of the fan, but could cause other problems, too.
Did you replace the fan speed switch recently, and do you still have the old one? If so, swap them and see if there is any change. That will tell you if the switch is the problem.
My switch(on the '74) doesn't work all the time. Sometimes I have to "jiggle" it to get it to switch speeds. I have a new one, but....I'm jest too darn lazy to change it! Adams' Apple38907.8811805556


Joel Adams
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             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

AC fan problem

Posted: 7/10/06 7:04pm Message 7 of 20
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Roseland, NJ - USA
Joined: 12/4/2003
Posts: 966
Vette(s): 1974, 454 with 4 on the floor, matching numbers.

Joel, I was in Reading PA today and Stopped at Stoudts Corvette and PU the relay and a new resistor. Hopefully, I'll get a chance this weekend to swap out the parts.

Thanks 




AC fan problem

Posted: 7/11/06 12:35pm Message 8 of 20
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BILOXI, MS - USA
Joined: 12/8/2001
Posts: 547
Vette(s): 1969 rag top
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.


Annicorvette
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AC fan problem

Posted: 7/12/06 8:01am Message 9 of 20
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Roseland, NJ - USA
Joined: 12/4/2003
Posts: 966
Vette(s): 1974, 454 with 4 on the floor, matching numbers.
No defroster


AC fan problem

Posted: 7/12/06 8:21am Message 10 of 20
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Joined: 3/19/2005
Posts: 385

Hey Warbird, I had the same problem with my 77 vette, check your fuses, high speed runs off of a different fuse. Mine is a 25 amp. I installed a bus breaker, (part number CBF 25 at NAPA). My fuse is located in the fuse box at the very top, it's a mother to get to for me because I am 6'4" so I find a smaller person or a very limber person to get to it. good luck, Gene

gs77vet38910.3493634259


in Forum: C3 Cooling and Heating Systems


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