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#1 |
Registered User
![]() Join Date: Jan 2005
Location: Denver, CO
Posts: 110
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blower motor: no high speed
have a 68 chevy w/ air. high speed on the fan will not work. i have replaced the switch w/out any luck. i konw the motor obviously works b/c it works fine on all the other settings.
anyone encounter this before? |
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#2 |
Junior Member
![]() Join Date: Oct 2004
Location: IDAHO
Posts: 46
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check the resistor
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#3 | |
Registered User
![]() Join Date: Jul 2004
Location: Turlock, Ca
Posts: 579
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Quote:
Yep !.....I went through this same problem and it was the resistor.
__________________
71 Custom 20 Deluxe..soon to be SWB 1/2 ton 1 incredible wife 2 great kids |
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#4 |
collector of vintage rust
Join Date: Apr 2004
Location: southern ohio
Posts: 421
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I know this is dumb,but sometimes its something simple...Did you check to make sure the cable was adjusted to work all speeds when you replaced the switch?....ask me how i know!
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#5 |
Registered User
![]() Join Date: Jan 2005
Location: Denver, CO
Posts: 110
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im pretty sure all the cables are working correctly. all the doors move correctly.
which cable needs adjusting? i unhooked the wiring harness from the switch and plugged in a new switch...same results...no high speed. there werent any cables to fuss with so i may require some 'splaining... and where is the resistor located? Thanks!! |
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#6 |
Registered User
![]() Join Date: Jan 2005
Location: Denver, CO
Posts: 110
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where would the resistor be located?
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#7 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Most likely it'll be the relay.
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#8 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,269
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There is a relay located screwed to the outside of the heater box. It is located under/behind the glove box between the heater and the pass side firewall. Believe there are like 3-4 wires attached to this relay via a plug connection. This realy can go bad and when it does, you loose high speed on the fan motor. You also need to make sure this relay has a good ground. This is not a unusual problem on to A/C trucks.
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#9 |
Registered User
![]() Join Date: Jan 2005
Location: Denver, CO
Posts: 110
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Are the relay and the resistor the same thing y'all are talking about?
I found the relay, located behind the glovebox (tore it up pretty good...brittle as candy) between the plenum and the kickpanel. But havent found any resistor...or are they the same thing? |
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#10 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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no, not the same. look for a plug that goes into the heater box...it is somewhere under the dash, i think in the same area as the relay.
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#11 |
Registered User
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
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Also check at fuse panel where orange wire from relay connects to the large red. This connection is prone to heating up (from being loose) and causing a bad joint. One way to check is to turn switch on and take a test light and touch to the orange wire at relay.
__________________
56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer |
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#12 |
Senior Member
![]() Join Date: Dec 2002
Location: Portland, Oregon
Posts: 901
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The high speed is controlled by the relay ( mentioned by others in the above messages). The resistor pack is for the lower speeds..
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'71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal). |
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#13 |
Registered User
Join Date: Jan 2003
Location: Damon, Tx
Posts: 56
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No high speed
I agree with Huck. I had this exact problem on my '71 w/ac. I replaced the switch; no high speed. Then I replaced the relay on the side of the glove box; still no high speed. Out of frustration I regrounded the relay on the glove box to the frame and bingo... High speed works.
Moral.. Check the simple things.. In my case I had a bad ground on the relay. Didn't need a new switch or relay. James |
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#14 |
Lovin' Life in Miss.!
Join Date: Mar 2004
Location: Puckett, Mississippi
Posts: 1,937
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The relay uses a bonding strap for the ground. The bonding strap is connected to the relay with a screw to the relay mount. The screw tends to back out because it is screwed into the plastic a/c case. Simple fix is to just get a bigger screw. Probably run another 30 years. I switched to a differant relay that has a regular ground connection and installed the ground to the firewall. This is the relay I used. http://www.partsamerica.com/PartDeta...artNumber=AC12
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The truck... you hear that? No really, you did hear that?!!! Last edited by chickenwing; 01-14-2005 at 10:06 AM. |
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#15 |
Registered User
Join Date: Jan 2004
Location: Garland TX Dallas area
Posts: 658
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had the same problew it was the relay 12.00 at auto zone.
__________________
1998 Pontiac Grad Prix GTP 1969 C10 396 TH400 3.08 posi |
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#16 |
Registered User
Join Date: Jun 2002
Location: central pa
Posts: 1,525
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It's the relay on the inside passenger side of the heater/AC box. 2 screws 5/16 I think. The resistor comes in the left side top through a gromet and the relay is right side across from the vacuum hose on the server for the kick panel.
__________________
72 longhorn c30 502BB/th400/fact air/4.11rear/ custom camper 72 bug(the better half's) under reconstruction 2009 HHR aqua blue 71 GMC k20 350/sm465 2009 Chevy hd3500 6.6 Victory Red crew cab dually Dave & Jeanne |
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#17 |
Registered User
![]() Join Date: Jan 2005
Location: Denver, CO
Posts: 110
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Thanks folks!!
i pulled the relay out and actually took it apart. it appears that about 30 years worth of water had settled into the part. since it actually mounts upside down, it "collected" that water and rusted everything!! taking it apart, i actually jumped the relay arm with the non-rusted-together terminal, and low and behold, HIGH SPEED! i was going to bend the rusted parts together, but then you dont have any other speed, only high. CMC Jim was correct: the relay is for high speed, while the resistor is for low. just for grins, i did check the resistor and it was fine. i want to thank everyone who contributed and helped me out! THANK YOU!! |
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