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Ac / heat blower motor

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Ac / heat blower motor

Posted: 12/1/23 1:06pmMessage 1 of 3
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OKLAHOMA CITY, OK - USA
Joined: 1/12/2020
Posts: 41
Vette(s): 1975 L48 Corvette Stingray convertible with hardtop, modified & restored, new medium cloisonne paint, interior, 350 cid 330 hp with TH700R4 automatic transmission 3:08 differential ratio, all power & ac and the underside. A very nice touring car.

1975 C3 Roadster

The high speed does not work.  Switching 3 speeds do, the last position does not.  I replace this switch 2 years ago with an ac Delco.

Could it be the high speed blower relay?

Is there a way to jump the relay to ascertain if it's bad?

Comments are welcome, thnx, Phil

 

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Re: Ac / heat blower motor

Posted: 12/1/23 4:41pmMessage 2 of 3
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Grapevine, TX - USA
Joined: 8/26/2006
Posts: 1537
Vette(s): 1972 LT-1 convertible with factory air. 2017 Black Rose Grand Sport M7 convertible.

That sounds like the blower motor resistor in the engine compartment.  It is mounted on the plenum and sticks into it for cooling of the relay.

 

This might help:

https://www.corvettemagazine.com/1963-1982-corvette-blower-motor-troubleshooting-and-repair/

   

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Re: Ac / heat blower motor

Posted: 12/1/23 7:50pmMessage 3 of 3
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22714
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

4 wires on the high speed blower relay. Orange, purple, dark blue, black. Orange is 12v feed from blower fuse. Purple goes to the blower. Dark blue is relay signal from blower switch, black is ground. Shoot 12v to the dark blue terminal, the fan should run high speed. If it does not run, the relay is either not grounding, or bad. You can also just check for 12v on the blue wire with the key on, blower switch on high. Voltage there with no high speed points to relay/ground problem. NO voltage there points to blower switch.

Joel Adams
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