C-3 blower again

[Lyndon S.]

I am still having high speed blower trouble with my 82 C-3. Last week some one was talking about a fuse, where would it be for the high speed blower? I have put in new blower, new relay, new resistor , new switch. And still can not get it to blow on high. What am I missing?

Kelly

[Jim T.]

Re: C-3 blower again

I don't know if the 82 has the same, however my 70 with air conditioning does have a separate inline fuse for the high speed blower function. The inline fuse is very easy to find under the hood near the master cylinder. Heavy guage wire comes from the horn relay, with the inline fuse very much viewable, and continues behind the wiper motor. Real easy to twist it open and remove the fuse and check its condition on my 70.

[Jack H.]

The circuitry is different on later Sharks...

While there are similarities (the A/C blower relay either takes fan low speed power from the resistor divider network or it bypasses the resistor network altogether for full battery voltage in high speed mode), there is no discrete wiring run to the engine compartment B+ bus on the side of the horn relay that contains an in-line fuse...

I'm looking at ST-359-80 which is Chevrolet's FULL set of schematic drawings for all 1980 passenger cars (including Corvette). One serious about doing electrical work on a 1982 Corvette should have a copy of ST-359-82. The later Shark guys are a LOT better off than those of us with early Shark cars because Chevy finally got around to publishing FULL electrical schematic diagrams in the mid-70's instead of the rinky-dink 'wiring diagrams' we have to live with.

What's the difference? A wiring diagram shows you how various black boxes are interconnected but doesn't disclose what happens inside a given black box. A schematic diagram gives full disclosure of the circuitry including what's happening within this/that 'black box'...

I presume the 1982 circuit topology is pretty much the same regarding the A/C-heater blower motor because A/C was a standard feature on both 1980 and 1982 cars. Bottom line, it's as I said before... The heart of the system is the blower relay.

When it's de-energized, power flows to the blower motor via the resistor divider network with blower speed based on which leg of the resistor network is selected to be output to the blower. When the relay is energized, the resistor network is bypassed and full B+ is applied to the blower motor.

Now, when you trace the path of the full B+ it is NOT as simple/clean as it is on early Shark cars (a straight run, though an in-line fuse, to the B+ bus on the side of the horn relay). NOOOOOOO!

On these cars, the B+ path is routed through TWO under hood engine harness assy's, crossing four plug-in connectors, and eventually reaching a tap on the alternator/regulator. PS, there's a parallel branch off this run that powers the underhood illumination lamp....

To trouble shoot this job effectively, the poster needs to have a schematic diagram to trace power flow. Don't just blindly replace components! Understand what's supposed to be happening and verify what is happening. Mr. Goodwrench is still in business to work on these cars if getting the right documentation is to big of a hurdle...