vintage air mark 4 underdash unit

[Dazed and confused89]

Is it possible to mount a mark 4 while retaining the original heater box on a 1969 GMC pickup 1/2 ton

[425HP409]

You can, although there is a clearance issue with the heater to defroster ducting. This makes the AC unit stick out too far from the dash. Back in the day,,, the AC manufacturers made a replacement defrost duct to replace the original one which allowed the unit fit flush to the firewall. I have one that was installed on my Dad's truck when he added under dash AC. I can send you pictures of it tomorrow if you pm me your email. I will also post them on the forum for all the other members to see. I have talked to Old Air Products about reproducing them, but have had no response from them. This would be a great product for anyone wanting to keep their original heater and defroster unit and add AC under the dash. If anyone out there is in the manufacturing business, I could let you copy mine to reproduce.

I have attached photos of the original defroster duct with the replacement one that was installed on my truck when the underdash unit was installed. It was one of those that just fit under the radio, not one that had the evaporator over by the passenger and the long plenum to the center of the dash.

[Dazed and confused89]

i thinking of mounting it under the steering column but im not sure

[caja_larga]

http://www.nostalgicairparts.com/content/help-8.php

I have a old unit like the one they sell here works great.

[Dazed and confused89]

Does anyone have one of those modified heater and defrost duct like shown in pics by 425HP409

[Dazed and confused89]

425HP409 do you have any pics of the underdash a/c unit u have in you truck and is there a floor heat duct on that replacement piece shown in the pics u sent me