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Heater on/off switch??

Discussion in 'Chevy Trucks' started by Hankster, Oct 14, 2002.

  1. Hankster

    Hankster Junior Member
    Messages: 16

    Yet another question!!
    This truck had an aftermarket AC on it at one time.It's gone because it never worked since we had it. Anyway. they installed a toggle for Heat-Off-Cool. How do normal Heaters without AC turn the blower off???? The factory in dash switch only has hi-med-low positions. Like to put it back to the way it was factory...but I don't know how Chevies shut it off !!! I don't have another truck like this one to look at....
  2. Got Grass?

    Got Grass? Senior Member
    Messages: 641

    Isnt "off" when the Vent, Floor, Defrost switch is all the way to the left?
  3. Hankster

    Hankster Junior Member
    Messages: 16

    If so,how does it work?? I pulled the whole heater/vent control deal loose from the dash when I re-painted it. In the "off" position...the "door" that controls where the air goes to is closed...but the fan is still turning..there is no "switch" on this unit to kill power to the fan. Whoever put that aftermarket unit in screwed with the wiring to do it....and i'm not familiar with how chevy turns the blower off,to put it back to stock condition!!!
    I know there aren't "toggle switches" sticking out of factory dashes for the blower..and my repair books don't help here either....this is a real dumb problem...no one here knows how blower motor is turned off???? Or am I stuck just putting a toggle in and the heck with it???
  4. Hankster

    Hankster Junior Member
    Messages: 16

    Guy on another site just told me on early 70's trucks(mine was built 9/74) that the fan COULDN'T be shut off...it was continuous run.....is this so??? From what I see in the dash...this could be true,but why on earth would they have engineered it like that???? A fan with no off control???
  5. raceman6135

    raceman6135 Member
    Messages: 61

    It's not that uncommon for a General Motors product to have no "off" position for the fan.

    I still drive a 1976 Chevrolet Malibu with a 3 speed fan that doesn't have an "off." It's "low", "medium" and "high."

    I can't say for sure what GM's official word is on this, but I've never encountered a problem with the system. Because air is constantly moving, it greatly reduces the chance that mould and mildew will start to grow if excess moisture finds its way in.

    Also, I've never (no, not ever!) had to replace that blower motor! I know it doesn't make much sense after all these years, but it's true.

    With regard to the heat/a.c. dilemma, it's the same fan that blows hot air from the heater and cold air from the a.c. In fact, when you turn on the "defrost" option with the heat/cold adjustment all the way "hot," the a.c. compressor will cycle! This is a way to ensure the a.c. gets used during the winter months so that all the parts of the a.c. system get lubricated.

    The slider that determines "floor" and "A/C" and "mix" etc is just connected to doors that deliver the air to the squirrel cage (blower motor fan). I don't know if that's how it is with the very new models, since I can't afford one (my newest vehicle is a 1986 C20 crew cab), but the earlier models used this.

  6. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    This has all been discussed before. If you do a search you will get more info. In your case, there is no off switch. It is not uncommon.
    My 80 GMC has no "off" either.

    The main reason the AC cycles when the defroster is on, is to provide "dry" air, to aid in defogging.

    I tried to reply to this thread yesterday morning, but had connection problems with PlowSite.

  7. Hankster

    Hankster Junior Member
    Messages: 16

    ok....now I got it. Will have to find where the clown that did this butchered into the power line.....so I can put it back to "factory" setup.
    Ac is gone,so it doesn't matter. Yeah,on my old Ford the AC did the same thing,for the same reasons..made good sense there.
    We liked the ability to turn the blower "off" because the door seal was bad,,and in the summer we got warm air blowing out....when it's 95 degrees out, last thing you want is more hot air!!! Fixed that tho with an inline water shutoff valve,just turn the hot water to heater core off for summer.....
    Thanks for the info,like I said...Chevy science is new to me...got to learn a new "language"!!!!
    Knew my old Fords inside out.....but thats ancient history now!!!! (Wife won't have one so.......)

    Closing up the engine on it now....and will be back working on the cab this weekend....so this info will be handy. Thanks again.