Heater questions

[oldtinrods]

I just wanted to start by saying thanks for any help you can provide.


I recently purchased my first 70 C10. The truck did not come with a heater in the dash, but the heater box, core and blower seem to be there. For some reason the PO had a 14 gauge wire wire running to the heater blower and back to a toggle switch in the cab with a 15 amp inline fuse. I would imaging that would work until I got the extra green together to buy the parts to make it original again, but it gets hot and pops fuses. I wouldn't think that blower motor would pull more than 15 amps. Am I missing something?

-Ronnie

[48richard]

Is this a heater-only or A/C truck? The OEM heater blower only draws about 6 amps. but the A/C blower draws 16 amps. Also I have heard on this forum that most of the replacement blowers sold are the A/C blower, so if it has been replaced with a repop part it could be the high current one anyway.

[oldtinrods]

Originally Posted by 48richard

Is this a heater-only or A/C truck? The OEM heater blower only draws about 6 amps. but the A/C blower draws 16 amps. Also I have heard on this forum that most of the replacement blowers sold are the A/C blower, so if it has been replaced with a repop part it could be the high current one anyway.

I'm sorry.. It is a non A/C truck, but the blower may have been swapped out over the years..

[oldtinrods]

Would anyone have any pictures by chance of a non a/c box? Like inside pictures and possibly the firewall. I am trying to get an idea of what I am getting into before I start redoing all of this.

This truck barely has any heat and it is my DD. I have found a few threads that help, but I am trying to get an idea of how it all works so I can find the real issue behind having very little heat.

I am guessing a clogged up heater core and that is where I am going to start.

[48richard]

This thread has pictures of all the heater boxes - inside and out.

http://67-72chevytrucks.com/vboard/s...d.php?t=439110

[oldtinrods]

Originally Posted by 48richard

This thread has pictures of all the heater boxes - inside and out.

http://67-72chevytrucks.com/vboard/s...d.php?t=439110

I think you very much for your help 48richard. Maybe you might be able to answer a question regarding all of this. If you are looking at the inside of the outer box you see a flap between the heater core and the blower motor.

• Is that the flap behind the plastic cap under the glove compartment?

• Is that what controls the cold --> hot setting on the heater?
  

[LockDoc]

-
Here are a couple of pictures of the cable routing. The top one 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.

LockDoc

[oldtinrods]

I have noticed when I close the flap to create more heat the wiring to the blower gets really hot and eats fuses. When I open it to allow it to cool the wiring will cool down.

I am now thinking that the heater core is possibly plugged with debris that was sucked from the outside causing the blower to overwork.

[PanelDeland]

WELCOME!!!!! The box being clogged is pretty common.The heat is controlled by a flapper in the box.That flap may be broken or inop.Be aware that sometimes a valve has been added under the hood to close off heat(water circulation) during the summer. If you remove the heater box,be sure to have the round gasket on hand,you will also need the sealer for the other half of the assembly.Most BB vendors or truck parts suppliers will have the round one(get it before you start since it's your DD).To remove the entire box usually requires removing the inner fender,you'll probably break at least a couple of the J-nuts(the ones that hold the inner fender bolts on the outter edge of the fender),spray liberally with PB Blaster before trying to remove them.You can probably help the heat a lot by taking the fan off and using a shop vac to clean some crap out but taking it apart will make a huge difference(you'll also know how it works for later troubleshooting).Check your fan(squirrell cage) since it may also be damaged.There is also a resistor mounted under there that the wires to the blower motor runs thru to give different spoeeds on the fan.
While you have it apart check the heater core and replace if necessary(trust me you will understand that you don't want to have to do this over).It's not a hard job it just takes time and patience.For the controls(if I understood correctly they are missing) try a Junkyard,if yoiu find one with damaged levers there is a rebuild kit available.

Again,Welcome to the board and just ask if you have other questions.

[oldtinrods]

Well friends the heater runs me out of the truck now... The shop vac trick worked wonders and I put in a 190 thermostat. The old therm was stuck. The issue with the wiring was the switch someone put in there was only rated for 10 amps. I now have heat in my DD again. Maybe after xmas I can afford to pick up a real heater for it..

Thanks again guys, I really appreciate your help!
-Ronnie

[longhorn70gmc]

Suscribed for future installation references.

[Neitzertjohn]

Hi Everyone , I have a 69 without AC , now the problem im having is the blower is not running. And i do have a good fuse. I have went in and checked out the blower it seems to be fine, i crossed a wire from the battery to the blower and the blower runs good. I also went in through the top of the heater box and looked at the little coiled res tier and i see no breaks in it. Other then the switch it's self could there be any other reason why this blower would not run. I feel like i have read just about every thread you have on this matter. Thank you so much for any help that could be offered.

[LockDoc]

NeitzerJohn-

I would guess the switch on the side of the heater control levers is bad then. You might want to unplug the connector from the switch and check the male and female spade terminals. I have seen some that were burnt because of a poor connection and overheating.

LockDoc

[Neitzertjohn]

Thank you LockDoc i will give it a try today