My Heater Mod

I have always wondered about the fresh air control knob. The control shuts off the air to the fan when pushed all the way in, at half pull it let's air bypass the heater core, and fully pulled will bringnthe air thru the heater core. The adjacent control will control the fluid flow from the cylinder head for heat and we also have a defrost control. By adding a baffle and cutting a little, I was able to make a cabin air recirculating function instead of allowing air to bypass the heater core. While I had it apart I also replaced the blower motor with a 15amp motor.
Now be patient, is gonna take a few posts.
I'm still trying to figure out the forum and pics via a cellphone.

 

First step is to remove the housing on the inside of the firewall that the blower motor attaches too. this is the section to the right in this picture.


notice how everything from top and bottom of the heater core enters the same cavity on the cab side.

Pull the blower motor off and clean the box
Next we cut 4 holes on the top half of the box. This will take a lot of rigidity away.

I made 4 trim plates to strengthen this area and hold bug netting / foam window ac filter media. I will get the exact hole size asap. There is like 16in2 of area that needs removed to maintain as much airflow as possible thru the system and too big a hole will interfere with the new baffle.

 

Beaming Pics....

 

here is the cab side of the heater with my divider in place.
this divider has 13 bends of varying angles and it took several lunches to model, but it worked without re-cutting.

this basically forces all the air to travel from the top of the heater core to the lower firewall cutout and into the blower. the air control lever now mixes fresh and cabin air. temperature is controlled by throttling the coolant flow.

 

this picture is with everything back in place. you can see the recirculating cabin air enters thru the bug screen. then it goes thru the top half of the duct to the air control baffle.
then thru the heater core and back thru the bottom half of the duct into the blower.
the blower motor is from a late 80s/ early 90s gm van with the brushes reversed.

 

JW60,
How has this worked out for you?? The new baffle looks like a bear to bend. Do you have a water flow shut off valve so u can get freash cool air in the summer. Would u do anything different the next time?
Thanks

 

@Tomellen
It seems to work a lot better.
Likely not as good as a Mojave due to core size but a lot better than before.
I had a fab shop cut and break the baffle, that was the easy part.
The blower motor swap is something that is easy and has sufficient improvement.
I have an inline shutoff for an 85 Toyota pickup (cable operated and correct hose size)
With the baffle positioned half way it let's fresh air thru the new recirculate openings.
If I were doing it again I would add AC.

If you want to do this and need help with fab files for a local laser or what not just send a pm with what you need and an email address and I'll move it up the list.
I am reworking this for 3d printing. I think that is becoming more available and i will need a test mule for the printed baffle.