Converting from A/C to non-A/C

[rikubot]

I am looking for some tips and tricks for doing this, mostly regarding the firewall, but any other pointers are welcome.
So far I have:

-Controls in the dash

-Trim pieces that cover the AC vents on the far ends of the dash frame

-The center dash pad without the cutout

-The heater box and defrost hoses

My biggest conundrum is figuring out how to mount it to the AC stamped firewall and blocking off the holes from the old unit. I'd like to make it reversible in case I want to put the AC back in. Has anyone documented theirs or know of any info I can use?

[b5blue]

I made a plate to cover all holes and attached it from inside with RTV. 

[rikubot]

I made a plate to cover all holes and attached it from inside with RTV. 

I like that idea. Do you have any pictures?

[rikubot]

I found this online. This might be the cleanest look I can get other than cutting and replacing a piece of the firewall.

[Nacho-RT74]

but that doesn't have heater either...

[b5blue]

Hey I've no pics and have installed Classic Auto Air since but that's exactly what it looked like. 

[rikubot]

but that doesn't have heater either...

Yeah I thought that was a little strange. I think the heater core outlets land on the upper right side of the old blower motor hole. They might come out of it just a little bit.

[tan top]

my charger had factory fitted AC , although when i bought it 31 years ago, all the under hood stuff was missing, was debating weather to swap to a standard box in for years, even  at the time i done a nut & bolt resto 20 years ago was still debating on swapping to a standard heaterbox.  i went back with the AC heater box  although a gutted & internally modified to kind of work as a standard heater ! anyways still was not really happy,  thinking AC has no place on a muscle car     beside  ( Buddy Baker , Bobby Isaac  never needed it )  
a few years back decided to finally fit a standard heater box , maybe i should have done it properly & fitted a none AC firewall  at the time of a nut & bolt resto but.... anyway  tried to do it as neat  as factory appearing as possible ( if that possible with a conversion method that did not exist ! or even look factory. but i done it is such a way that what if there was only one fire wall AC , then blanking plates were used for none AC .
   after i accumulated most of the parts ( still not got the end & centre dash vent blanking parts yet this is a long story in its self partly because the end pieces dont fit a AC dash with out work, will sort it one day )
  i looked at  where the none AC box would go & thought this would be simple as taken the charger apart millions of times over the years ! not literally but you get the idea , anyways fitting the heater box in correct location took a long time aligning removing checking then aligning again a lot of trial & error plus a few rude words i was not as agile as i once was  .
i cant remember with out checking!  none of the holes in the firewall matched the none AC heater box, but for a reason i cant remember right now with out looking, i changed the location of 1 or 2 of the studs on the back of the none AC heater box to match  one or two of the AC fire wall holes. i made blanking plates for all the unwanted AC fire wall holes,  to blank the AC fan blower motor hole i managed to obtain part of a none AC firewall it was the part that was needed to cover the fan motor hole & give the location of where the holes are none AC fire wall for the heater core tubes to poke through, i cut this carefully & made this a bolt on blanking plate also , in an  attempt to make it look like what if it was a factory installed part, like i mentioned above ! what if there was only one firewall for our chargers ) i know i'm kidding my self !  but it was neat & good enough for me & come out much better than i thought.
 besides  could not face stripping out the charger again welding in a none ac fire wall also i dont think doing that would be a good idea , OK for a XP charger no offence XP guys , my way if i wanted to go back to ac there is only an number of tiny holes to weld up & repair about a 1/2 square notch cut in the AC fire wall for the  none AC heater core pipes , again easier to change back than a complete or half a fire wall !
 for  the AC heater heaterbox  stud  mounting holes in the fire wall  that are not used , i simply used suitable size dome headed coach bolts , for  attaching  all blanking plates i used  the old OEM tiny hex head self tappers that attach the front &  back of the heater boxes together , new hex head self tappers are supplied in a heater box rebulid kit , i could of used modern panel bonding techniques on the blanking plates! but wanted to make the attaching method a feature , but not if you know what i mean , besides  if it was  factory installed blanking plates it would not have been stuck ,   maybe just bolted     lot of what ifs maybes  

 once all coach bolt  domes & hexheads were painted body color  & everything  put back on the fire wall , it looks kind of maybe factory what if etc   & overall pleased with how it turned out.
just read this post back to my self , hope some of it dont sound too confusing ! seemed ok when i was typing it

[Nacho-RT74]

  besides  could not face stripping out the charger again welding in a none ac fire wall also i dont think doing that would be a good idea , OK for a XP charger no offence XP guys , my way if i wanted to go back to ac there is only an number of tiny holes to weld up & repair about a 1/2 square notch cut in the AC fire wall for the  none AC heater core pipes , again easier to change back than a complete or half a fire wall !
 

but you modified the original XS firewall.... I was installed a non AC firewall before cut and patch the original one ( just my opinion which is for sure irrelevant LOL )

Damn, I'm so happy having A/C!!!!! LOL

[tan top]

 besides  could not face stripping out the charger again welding in a none ac fire wall also i dont think doing that would be a good idea , OK for a XP charger no offence XP guys , my way if i wanted to go back to ac there is only an number of tiny holes to weld up & repair about a 1/2 square notch cut in the AC fire wall for the  none AC heater core pipes , again easier to change back than a complete or half a fire wall !
 

but you modified the original XS firewall.... I was installed a non AC firewall before cut and patch the original one ( just my opinion which is for sure irrelevant LOL )

Damn, I'm so happy having A/C!!!!! LOL

    Yeah !    your right ! i see what your saying ,   yes i did ! was hoping i had got away with out doing that & or would have to make a smaller notch , but by the time i figured out i was going to have to do that, it was too late ! had decided there was no going back,       besides its only  a minor job to fix it  compared to changing a firewall mine is modified on the underside anyway !   have torque boxes  front & rear , hemi reinforcement plates & chassis connectors , also  most of the factory spot weld joints frame to floor etc  ive seam welded for extra strength also but you cant see it    

yep Agreed AC good ! & have it  on my daily driver  ! but not on a muscle car  charger  roadrunner  superbee etc

the   55 chevy  in two lane black top!   did not even have a heater ! because it slowed it down  

[Nacho-RT74]

Well I daily drove my muscle car ( when it was in one piece LOL )... well, if we can consider a 74 400 really a muscle car ( stroked by now anyway, and still with AC LOL )

[tan top]

Well I daily drove my muscle car ( when it was in one piece LOL )... well, if we can consider a 74 400 really a muscle car ( stroked by now anyway, and still with AC LOL )

yep 74 charger a muscle car 



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this is what i was attempting to describe in my above posts ,  my firewall now !  after removing the factory AC ! converting it to a standard heater box set up
if i was to do this again today , i would make one of the blanking plates a slightly different shape  

[rikubot]

Well I daily drove my muscle car ( when it was in one piece LOL )... well, if we can consider a 74 400 really a muscle car ( stroked by now anyway, and still with AC LOL )

DEFINITELY a muscle car, especially with a stroked 400 

[rikubot]

Thank you for the pictures Tan Top. I really like how that came out. I'm asking around for a piece of a non-A/C firewall to try to replicate what you did there. I was thinking a bead of seam sealer in the back would work to keep water out. I decided to go the heater route for a few reasons:

- cheaper

- lighter

- missing most of the parts

- slightly more power

- I like the look of the engine bay without the compressor bolted on

- also prefer the dash w/o vents

The car never had working A/C while I've owned. I would just open up the vent windows and cowl vents. It also had fabric seats which seamed you help a lot. I don't want to cut out and replace the firewall JUST IN CASE I change my mind later and can afford to do the whole system lol.

[rikubot]

Tan Top, I do have an extra pair of the vent blanking plates that go on the ends of the dash?

[rikubot]

I had the same dilemma with my AC dash which had the vent cutouts. I ended up fabbing a couple block-off plates out of some spare sheetmetal (I think off a file cabinet haha). I shaped them and screwed them in from the back. Rivets would have worked better than the screws because they would have left a little more clearance for the plastic trim but they ended up working out pretty well.

[tan top]

I had the same dilemma with my AC dash which had the vent cutouts. I ended up fabbing a couple block-off plates out of some spare sheetmetal (I think off a file cabinet haha). I shaped them and screwed them in from the back. Rivets would have worked better than the screws because they would have left a little more clearance for the plastic trim but they ended up working out pretty well.

looks good !  going to do something similar one day, although after attaching strips of metal to make the holes smaller, thinking covering that corner section each side with vinyl then screw the blanking plates on , not sure yet , i'm undecided what to do. as for the corner sections , i would like  original used SE wood grain pieces dont want new or real good parts etc well sort of want it  all to blend in match same age looking  , reason being when i stripped my charger down to the last nut bolt clip & screw when doing a nut & bolt rebuild & went through every single part etc , restored , cleaned , checked etc  , i only replaced what i had to , not just things for the sake of it ! wanted it to look old  ... not new ! not false  over restored plastic looking , no offence to these cars ! they look awesome , but not the look i wanted for mine. i even put back the pitted aged original badges !  
  if  your going to duplicate or make your own version of what i done , have a look at the pictures below  , this is roughly the shape the blanking plate i made  for the ac fan blower motor hole , the others are self explanatory! i made all blanking plates roughly 1/4 -1/2 inch bigger than the holes they were covering where possible, & attached the from the out side , as mentioned wanted to make them a feature type thing. only one attached form the inside was the water valve hole. make a template for the blower blanking plate out of card or similar first because its tricky where the standard heatercore tubes poke through the firewall , right close to a vertical strengthening rib. there is almost no room for over lap in that location , although it depends on how you go about it . i remembered why after looking at mine again , why i moved two of the standard heater box mounting studs to use the original AC box holes in the fire wall , it was because one of the  standard heater box mounting studs is right in the middle  of the blower motor blanking plate ! thought for strength would be better not  to use that area as a main attaching point ! ( you can see on mine i have a plastic plug in that hole) going to attach a stud on the back  of my heater box in the factory location one day , will require a bit of extra work because the stud mounting will need to be a different height slightly taller than the other three or just ad a shim   , as the blower motor blanking plate is on top of the firewall  , so i will have  four attaching points  ( stock is 3 ) , was just my preference to move the mounting studs .. i tend to over think things when it comes to the charger & take no chances  

i also made a new thicker  heater box to inner upper cowel support strap.
 yes used  3m seam sealer around the holes on the out side before screwing the blanking plates on , then once in place wipe more sealer around the out side edge lip between the new blanking plates & firewall , inside  do the same seal up around the holes etc .

i did not see you mention  you have the right side cold air vent cable ?
also silly question i know !  have you made sure you have a 68 /  69  heater core only it has  two 5/8" tubes  , the 70 core has one 5/8" & one 1/2" for some reason  
  run into any problems post them up we will all try & figure out whats going on

[HeavyFuel]

I restored my original A/C car to non-A/C.    Mines '68 but should be close for '69....if not the same.

OP,  I'm not sure why you're going through all of the steps you suggest when you stated you want it to be reversible.    

Here's what I did:

1. Left off everything A/C related under the hood.

2. Left the dash as is.....a few extra vent openings are a good thing.

3. Used the factory A/C dash controls.

4. Used the original heater-A/C box under dash.

5. Modified the area inside the heater box where the A/C evaporator lives in order to direct airflow when you want in-cabin ventilation.

6. Blocked the evaporator firewall holes with 1/8" stick on insulation material that I used on the entire floor and firewall.  


I think that's about it....I may have forgotten about a small detail or two.


My controls work, heater works, dash vents blow air when selected, firewall looks nice, dash looks nice, everything is reversible.

[rikubot]

Heavy Fuel,

I had considered going that route as well but decided no to for a couple reasons. The bigger reason is that my AC box is a couple states north with a "friend" who was supposed to blast and powder coat it. He no longer answers my texts so I think it's a goner. The seconds reason is the expense of gathering the stuff to get to where you are on the inside of the cabin. I originally intended to go that direction 

Tan Top,

Thank you very much for the detailed description and drawings! I couldn't ask for a better tutorial. I see why you would want to relocate that one mounting point that bolts to the circular blower motor block-off plate. I am torn between relocating a mounting point or using the one on the plate and re-enforcing it somehow. Like you said it would probably be fine as it isn't very heavy, but I'd rather be safe than sorry as well. Do you know if all B-bodies used the same firewall, including four-doors? I was thinking of checking out the salvage yard in town but I know for a fact that they don't have any two-door b-bodies.

I actually don't have any of the vent cables other than the driver's side fresh air vent. I did make sure to get a heater core with the right diameter inlet and outlet holes. I went with a Spectra brand core and it is a piece of junk. Fits like garbage, but I checked it for leaks and it passed the test so I'm going to make it work. It is aluminum instead of brass.

[tan top]

 yes as far as i know given like for like  AC or no    67 -70 B-body  2 & four door fire walls are the same .
if your really stuck in finding a part of a firewal , you could always make the blanking plates out of appropriate gauge  sheet metal.
its  a long story in its self why i chose  to use a section or original none ac fire wall 

[marshallfry01]

It must be nice living in a climate where a/c isn't a must! Summers in Arkansas are so hot and humid my car will have to have it. Especially if I expect my wife to go anywhere with me. 

[rikubot]

Haha yes I am lucky that even though it's hot here, it's a dry heat. This week is going to have highs in the hundreds, though. Makes me think twice about losing the A/C. That's nice that you consider the wife. That thought didn't really cross my mind 

[Nacho-RT74]

it's soooooo pleasant to have A/C! if you don't need it , don't use it, but will come the day you'll needed and not have it will regret it.

All new "muscle cars" got A/C!!! think on that LOL.

Venezuela got a variety of weathers on all the extension, but I think the main reason to have A/C is when a tropical rain falls! no matter what you do, glasses will fog inside. Then the A/C is a must!

Next reason nowdays, safety reason againts some thiefs, where some situations having the windows up, will help a bit.

[b5blue]

PLUS B/RB puts out bunches of heat! After 22 years driving my 70 A/C was a game changer. Even other guys with old cars noticed me widows up and commented. 

[HeavyFuel]

We definitely get some heat up here in ND...but by no means does it dominate our climate.

My rule of thumb is to leave the car in the garage once the temps outside hit 90*.  There are plenty of days in our summer to enjoy driving without baking my car to death.    

Maybe I baby it too much.  I also raise the hood to ventilate the engine bay after a every drive....unless I'm in public.  Please tell me I'm not the only one of us doing this.  

[rikubot]

I kinda go on the same thought process. I also was struggling with vapor-lock issues 

[rikubot]

Tan Top, do you remember what gauge steel you used for your block-off plates?

[rikubot]

I'm getting ready to drill the holes to mount the heater box in the car. The box doesn't mount against the cowl (where the big rubber ring sits) how I thought it did. It seems it just presses up against whereas I thought it sat around it. About how close does the box sit with the cowl? How smushed should the rubber gasket be? Any measurements of where the holes should be would be greatly appreciated 

[rikubot]

I cut a few plates for the holes and bolted them in. It looks okay. I definitely like it better with them on the inside. You can see the template I made for the big hole in the first pic. I took that template to a metal shop in town and they are supposed to cut it out for me in 14 gauge metal with a cnc plasma cutter. They said it won't be ready til Tuesday so I can't check the fit until then.

[rikubot]

Got my block off plate back from Midwest Steel in Pueblo, CO. Not too shabby!

14G steel cut with a plasma cutter. $32 and change.