Heat only controls (what cable does what?)

[sventinker]

In my 70 no a/c c10 my father in law added the factory style a/c heat controls and none of the cables line up with the new control. So I want to learn what the cables do so I can figure out how to rig it for heat and or defrost this winter. Would a heat only truck have 2 or three cables? would it have a shut off valve in the line feeding the heater core? Is my stock fan motor 1 speed? or does it vary based on resistors? The fan control I have now has multiple positions.

I know its a lot of questions but I don't know anyone with one of these trucks I hope you guys can help thanks.

['68OrangeSunshine]

I believe the Standard Heater Control had 3 cables.
DEF

FAN

HEATER

[LockDoc]

Originally Posted by sventinker

In my 70 no a/c c10 my father in law added the factory style a/c heat controls and none of the cables line up with the new control. So I want to learn what the cables do so I can figure out how to rig it for heat and or defrost this winter. Would a heat only truck have 2 or three cables? would it have a shut off valve in the line feeding the heater core? Is my stock fan motor 1 speed? or does it vary based on resistors? The fan control I have now has multiple positions.

I know its a lot of questions but I don't know anyone with one of these trucks I hope you guys can help thanks.

3 cables. No valves in the lines. A diverter door controls whether air goes through the heater core or not.

Here are a couple of pictures. The top cable on the control goes to the front control arm, the middle one goes behind the heater box and to the bottom, and the bottom one goes around the heater box and into the heater box by the firewall.

The third picture is the blower motor resistor. It's located on top of the interior heater box on the right side. They can be pretty fragile so use a small screwdriver to gently pry the connector off if the terminals. I think the blower motor is basically a single speed motor and the resistor controls the low and medium speeds. High is a direct 12 volts. The switch is on the side of the heater control panel and the middle lever controls it. You can see the switch in the first picture where the connector is.

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[sventinker]

Ok thanks, So the control I have is for an a/c truck. I Don't know why he added that as he never spoke of putting a/c in this truck. Looks like the cables go in all different on the a/c control versus the heat only and the electrical plug is different as well. Thanks again for the information

[LockDoc]

Originally Posted by sventinker

Ok thanks, So the control I have is for an a/c truck. I Don't know why he added that as he never spoke of putting a/c in this truck. Looks like the cables go in all different on the a/c control versus the heat only and the electrical plug is different as well. Thanks again for the information

No problem. Any more questions let us know....

LockDoc

[LukeandI]

Why not just swap out the ac control to a non ac control? They are a dime a dozen. OK... not quite :-)

[sventinker]

So I went to hook up the motor so I could get some heat in the cab regardless of where it comes out and the motor was bad. $20 later and the motor is replaced Just got to love how inexpensive some of our parts are. I figured what wire was what and made my own harness to the stock plug I have all three speeds now.

So that brings me to this issue and I know you guys might say to pull the air box but in this picture I can see where one of the cables are supposed to go but is there a plate missing? what goes in this hole? And I assume this is the flap that will circulate air through the heater core? Anyway a lot of air comes out of this hole and when I cover it more air comes out of the floor vent. When I divert to the window defrost without and ducts installed yet very little air comes out of those holes.

[LockDoc]

Originally Posted by sventinker

So I went to hook up the motor so I could get some heat in the cab regardless of where it comes out and the motor was bad. $20 later and the motor is replaced Just got to love how inexpensive some of our parts are. I figured what wire was what and made my own harness to the stock plug I have all three speeds now.

So that brings me to this issue and I know you guys might say to pull the air box but in this picture I can see where one of the cables are supposed to go but is there a plate missing? what goes in this hole? And I assume this is the flap that will circulate air through the heater core? Anyway a lot of air comes out of this hole and when I cover it more air comes out of the floor vent. When I divert to the window defrost without and ducts installed yet very little air comes out of those holes.

You can see the rectangular plastic plug that goes in that hole in my second picture above, and where the cable fastens to the bracket. The round end on the cable slips over the pin you can see on the diverter door inside the heater box and there is a small round spring clip that holds it in place.... The cable opens and closes that door. You should be able to reach in and push/pull on that pin and open and close the diverter door if it isn't stuck.

LockDoc

[sventinker]

Ok I see that now. So that's going to be a pain to find one. So that door deep inside there does what? and the cable on the bottom of the air box does what else. I see the one on the front does floor or window defrost.

[LockDoc]

Originally Posted by sventinker

Ok I see that now. So that's going to be a pain to find one. So that door deep inside there does what? and the cable on the bottom of the air box does what else. I see the one on the front does floor or window defrost.

The door allows air to pass through the heater core or shuts it off so no air passes through the core. Since there is no valve in the heater hose to control the amount of heat to the heater core that door controls it. The lever on the bottom of the box controls the overall air flow and works in conjunction with the speed of the blower motor. The lever on the front controls the heater/defroster function. As far as the retainer clips that hold the cables to the levers if you look at the cables where they fasten to the in dash heater control it will have the same kind of push on clips.


Here is a thread I posted back in 2006 on removing the retainer clips without breaking them and it shows a close up picture of the clips.

http://67-72chevytrucks.com/vboard/s...d.php?t=211815

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