jcloving

Hello Everyone,

I want to disable my blower fan from running in the leftmost switch position. I know GM wanted it to run all the time but I want it off in that position.

For my '76 L-48 I believe one of the wires going into the resistor on the a/c box is the culprit. Could someone spell out exactly which wire? There are four: dark blue, yellow, light green and light blue. From my best guess, I think it is the yellow wire.

Let me know,

John

jb78L-82

On my 78, there is a relay under the hood right against the firewall on the passenger side just below the hood latch a little inside towards the engine-Pull the plug out of the relay like I have done for the last 25 years-no blower in the off position. I leave it plugged in in the winter months and pull it out during the hotter months since I removed my A/C compressor about 20 years ago. One of my projects is to resuscitate the A/C one of these years. Don't really miss it on the L-82 though.

speedreed8

there should be two wires that go to the blower switch, yellow and orange, the orange wire supplies power through the switch when off to run the blower on low. depends on how bad you want to dig into the console to cut and disable it.

Easy Mike

Don't quote me on this, but I believe the tan wire on the switch under the console is the low speed on all the time wire.

jcloving

Thanks guys. I was planning on using a voltmeter to check the resistor wires one by one with the key in the on position.

Are there any other '76 owners that have done this modifiation?

lars

I don't know why you'd want to - it's an effective safety feature. You should disconnect your rear brakes while you're at it.

Lars

chucks

There are 4 wires going into the plug on top of your AC box. Insert a small screwdriver in to the opening the dark brown wire is in, probe around and pull on the wire as you insert the screwdriver and it will come out. Tape the end and tie it back. This will shut off the low speed on your blower.

iokepakai

Thought about doing this also.Decided against it due to safety reasons.Should you have an exhaust leak into the cabin without knowing it and your windows are up,would not be a good thing.The battery is also located in the cabin and it does vent fumes..

MrJlr

Not that I doubt your expertise - but how is it a safety device - how does it work ?

bobs77vet

must be related to fresh air and carbon monoxide poisioning

jcloving

I can tell you why I want to do it. I want to keep even more hot air out of the cabin.

I have a hot water shutoff installed and I still feel a small amount of warm air blowing through the vents. This is with the heater/ac controls in the off position. I have replaced all seals in the ac box, inside and out. Also replaced the drain tube. The hood seal is in place and is working.

My guess is that the heat of the headers is putting some heat into the ac box. As the fan blows it is picking up this heat and putting into the cabin.

Thanks for the tips. I will let you know when I have results.

iokepakai

Cabin heat was also an issue.When I did my trans swap I replaced the missing heat shield in the trans tunnel and install the bellhousing collar.Those two items decreased the cabin heat a whole bunch.....
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I'm Batman

I lined the inside of the HVAC box with Refletix when I had the system apart. It did wonders for the problem you're describing.

superdave269

Did you block both of the hoses to the heater core? I put a small brass ball valve in each one(from home depot) and for the first time the passenger didn't get burnt feet. Wish I done it years ago. I believe the heater bypass valve didn't work. Be sure to block both hoses. Plus with a ball valve you can just open them back up if you need heat.
You can also put in a bigger fan, or put reflectix(lowes) under your carpet. I did this to another C3, but had best luck with the 2 ball valves.

I'm Batman

The factory heater shut-off valves are terrible. The modern plastic replacement that should be available at any parts store is a much more functional piece. It's not for the NCRS types, but it's great for a driver.

riverracer au

i found the hot air around my feet was from the 3 or 4 missing rubber plugs that is supposed to hold the carpet in place behind the pedals.
found when i had the carpet removed and was putting a pre-cut insulation kit in.
i placed a spotlight under the car, shut the shed door, and there was all this light in the footwell.
replaced with new blank grommets, bugga all air movement around my feet now.

silver79

I have a question on the same subject, my blower like yours always blows hot air but the only setting that chances the air flow is the High setting all the others don't seem to work. Any way to fix that?

Thanks

lars

I was working for GM when this feature was designed and put into use. GM had several cases of carbon monoxide getting into the interior of the cars - especially on Corvette. A few people ended up getting killed as a result. The lawsuit was massive. The blower on "LO" keeps a positive pressure inside the car when the windows are rolled up so you don't end up dying.

...so if you're going to bubba-fix a hot air problem, caused by defective seals and a bad heater box, by disconnecting a safety device, I think you may as well disconnect those pesky brakes while you're at it.

Lars

jcloving

Thanks Lars,

I will post pictures when I have results.

MrJlr

Awesome explanation....thanks