Blower Motor/Ignition Switch

[crebo]

Hello to all,

Before I get started. I live on the Mississippi Gulf Coast and cruisin the coast is in full swing.. The cars here are unbelievable.

Anyway I have a 77. I had the AC fixed here recently... When I picked it up It seems to have one problem. When I have the key in the ignition and turn it to the accessory position (forward before the car turns on..... if that's the acc position) the blower motor comes on low. The local mechanic claims it was "astro ventilation" which I researched and doesn't seem to be true. He also claims that it is hooked up properly. Needless to say that I don't have alot of faith in my the mech. I called Zip, where I purchased the AC/Heater control head assembly. They told me that it could be my ingnition switch needing adjustment.
I'm just wondering how hard is that to do....? Exactly where is the switch...? And does that sound like the culprit?
I would rather fix it myself if I can. I can follow directions fairly well.

Thanks Chris

 

[bmotojoe]

Your mechanic is correct. You do have what is called a Manual Astro-Ventilation system. Also when you look at the heater A/C indicator faceplate fan switch as far as speeds are concerned you see LO - - HI there is no off. Your fan is actually a 4 speed fan and its normal for it to run on low speed when the fan selector switch is in the LO position. I am surprised that the vendor that supplied you the A/C Heater control assembly didn’t know that! Well not really.
Brian

 

[6880 Mike]

I agree. The blower fan is meant to run at low speed on some years with the ignition on.

 

[crebo]

I guess my problem is when I orginally purchased the car in 98 and the AC was working it didn't function that way. With the key in the ignition and turned a quarter turn forward the blower never came on. When I called the tech at ZIP's I was again told that Astro Ventilation stopped on the 76 model....he also said that my mech possibly crossed the wires or it was the ignition switch.

Thanks guys

 

[bmotojoe]

I have owned my 1977 since 1982 and the low speed fan has always worked like this and is correct, trust me. I would refer to the 1977 Chevrolet Service manual section 1A Heater, Astro-Ventilation for a complete description on how the Manual air conditioning works in our Corvettes. The links below are of the cover of the 77 service manual and the other is of the first page in section 1A.
Hope this helps,
Brian
http://s239.photobucket.com/albums/...current=1977ChevroletSerrviceManualMedium.jpg

http://s239.photobucket.com/albums/ff238/bmotojoe/?action=view&current=ASTRO-VENTILATIONMedium.jpg

 

[Bob Chadwick]

When I have the key in the ignition and turn it to the accessory position (forward before the car turns on..... if that's the acc position)

The accessory position on the 77 requires one to turn the key backwards rather than forwards. The forward position is ignition then start.

 

[crebo]

Thanks guys.....