Corvette C3 Forum 1968 through 1982

Little Help with a 1973 Non Air Blower problem

Old Aug 22, 2022 | 09:25 PM
  #1  
jdoming728's Avatar
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Thumbs up Little Help with a 1973 Non Air Blower problem

I have been building cars for over 40 years but I have never owned a non air con vette.... Three things I need advise on.. Where is the blower resistor? where is the Blower relay, My blower works and is brand new but works slow don't push much air, Any advise for the old newbie??
 
Old Aug 23, 2022 | 10:50 AM
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Welcome to the forums! First a service manual might be your best friend. Had a 70 convertable non air years ago don`t remember all the wiring, It is a very simple system for non air. Fan switch, check the switch making sure its working correctly. One relay for non a/c (I think could be wrong) its the high speed fan relay up above the heater housing (controls high speed fan) it should click on high speed. the Speed resistor should be close to the relay also on top of the blower housing 2 screws. Not knowing the condition of your heater,I would say it needs cleaning! Between leaves and other tree debris and tiny 4 legged buddies. you might want to consider pulling the housing apart as to replace the heater core just to clean it out, if it hasen`t been done recently Check the cable control operation to make sure the heater doors a working properly. For years pens and pencils would fall down the defrost vent and end up in a vent door. Hope that helps!
 
Old Aug 23, 2022 | 05:56 PM
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Originally Posted by thomas77
Welcome to the forums! First a service manual might be your best friend. Had a 70 convertable non air years ago don`t remember all the wiring, It is a very simple system for non air. Fan switch, check the switch making sure its working correctly. One relay for non a/c (I think could be wrong) its the high speed fan relay up above the heater housing (controls high speed fan) it should click on high speed. the Speed resistor should be close to the relay also on top of the blower housing 2 screws. Not knowing the condition of your heater,I would say it needs cleaning! Between leaves and other tree debris and tiny 4 legged buddies. you might want to consider pulling the housing apart as to replace the heater core just to clean it out, if it hasn`t been done recently Check the cable control operation to make sure the heater doors a working properly. For years pens and pencils would fall down the defrost vent and end up in a vent door. Hope that helps!
Yep Have the manual and am very familuar with older vettes but I didnt realize that the non AIR vettes do not have a fan relay switch and that the Blower resistor is under the passenger dash... Thank you for the come back and as I said Im a old Newbie!
 
Old Aug 23, 2022 | 06:53 PM
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That`s good to know where the resistor is. (I was guessing)It`s never too far from the fan for the cooling reason. I can`t imagine a vette today without A/C convertible or not too hot anymore and can`t take the heat like I used to. It`s expensive to add on but would help the valve of the car. Something to think about..
 
Old Aug 23, 2022 | 10:25 PM
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Welcome to the forum. IIRC, the blower speed resistor is in the plenum. It is an open wire, multi-legged resistor that looks like a heater coil. It's there to keep it cool. Each speed has a different tap on the resistor. The High speed bypasses the resistor and triggers the relay which prevents the high current from going thru the switch.

In my defense, it's been about 45 years since I put factory A/C in mine and my memory isn't quite what it used to be.
 
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