Dash Swap/ HVAC Units

[matthewh]

So like alot of other members, im in the process of swapping in a CTD into a 70's era Dodge W Series. I notice if they swap the dash's from the donor vehicle, they swap the HVAC units as well. Is it possible to swap the dash, but leave the HVAC unit?, I.E, use a 93 dash with a 77 HVAC unit, and have the controls work properly?
Retrofit the 70's heater control panel into the 90's dash? IDK, throwing out ideas

Not worried about A/C, as i've removed the compresser from the engine, and have no interest in running it for this project.

End goal is to be able to use the donor wiring harness, and not have to do alot of firewall mods to run an HVAC box I really dont need.

Thanks

[thrashingcows]

Can't see why not. You might have issue with the glove box door? And would the heater controls work the same...not sure. The early 70's stuff might all be cable operated, with wiring for the blower motor only. The HVAC control panel in the 1st Gens are vacuum operated, so more then likely you's have to try and make your original 70's cable operated panel work with in the newer dash opening.

I have never done this, and I'm not really familiar with the early pick up stuff. Just throwing out ideas.

[Mark Nixon]

Non-A/C '81-'93 trucks are also cable operated.

FWIW, even the 1972-1980 A/C dashes were vacuum operated, though the non-A/C, once again, were not.

Mark.

[matthewh]

I know the 70's stuff is all cable operated, at least in my truck, as I had to replace all the cables when I bought it from the Gov't. I also know that my donor truck, 93 with AC had vac controls. Was hoping to just unbolt the old dash and slid the newer one over and run with it.

Mainly after the elec's for the grid heaters and the TPS for the Auto. I know I know, you can run the trans with a pressure switch, btdt, wasnt happy with the performance.

At this point, I'm still on the fence about it, but was looking for info on if it was even possible.

Thanks again

Matt

[m880cummins]

I looked into it with my Crew cab. The biggest issue was not the vacuum stuff. The ducting would have required a lot of custom work. You would need to fabricate a hose setup to the defrost vents.....With the amount of time you need to spend rigging the thing together, find a correct HVAC box and then drill the couple extra mounting/plumbing holes and do some minor trimming and you will be done. Actual time spent modifying the firewall should not be more than an hour and will eliminate the nightmare if you choose the other way.

Either you run all 1980's or all 1970's. Mixing and matching is a wiring and design nightmare (more than factory). I have both the 1970s box and 1980s HVAC boxes I need to get rid of.

Just my .02

Charlie

[matthewh]

The donor truck has a good dash/hvac unit, I was just hoping not to have to modify the firewall, but if its as easy as they say, I'll probibly go that route.