2020-B4-3

Author Topic: Bring back the factory air on my 78  (Read 316 times)

TacoTownCharlie

  • Active Forum Member
  • *
  • Posts: 10
Bring back the factory air on my 78
« on: July 03, 2020, 04:31:05 PM »
I have a 78 Trans Am (Y88) with the Pontiac 400 (L78) and factory AC.  I have the mostly original condenser,  compressor and evaporator under the hood; all of the AC lines are currently disconnected.  Under the dash I have the control panel and the heater box but none of the air duct parts.  I live in Arizona so I need a functioning system.

I wanted to install a Vintage Air system.  This would fix everything at once - I wouldn't have to worry about any part of the current system.  Everything under the hood would be swapped out with a new system designed to work with a newer refrigerant.  I wouldn't have to worry under the dash with the vacuum control lines, actuators, duct work, vent doors and electrical switches.

I would give up the factory dash controls, some foot space for the front passenger, some glove box space and I would lose the evaporator box under the hood.  And by most accounts on the web I would have a colder/more efficient system.

But I wanted to give the factory/stock system one more chance.  Under the hood I can put in a better, lighter and more efficient compressor like the Pro6ten.  I also like the parallel flow condenser - it sounds like it would allow for more heat exchange.  It doesn't look like there have been any major advances in evaporator design that still fit the factory case but at least there are new stock evaporators available.  Since these would be new parts under the hood there would be no refrigerant conversions issues.  I would need new AC lines to make everything complete.  So there is a path forward under the hood.

Before I spend a lot of money under the hood I want to make sure everything under the dash can be brought up to working order.  If I can't get that part of the system to work then I'm going to install the Vintage Air system and tell myself that at least I tried.

My plan is to check, repair and replace the vacuum control system first.  I'll probably need to spend some time with the vent doors the actuators control as well.  I should replace the heater core as well since I'm in there.  Sounds like I might take the heater box off the firewall, no joy there.  Then work with the cable control on the Hot/Cold lever (I think that is the only cable control) and then work on the electrical system starting with the fan control switch.

This is a major project for me so just putting my thoughts and plans up here will help me keep my focus.  Feel free to let me know if I'm missing anything major or if you think I should rethink my approach, I'm open to any ideas.

Tony

TacoTownCharlie

  • Active Forum Member
  • *
  • Posts: 10
Re: Bring back the factory air on my 78
« Reply #1 on: July 03, 2020, 05:07:45 PM »
So I want to start with the vacuum control system.  I'll need a vacuum source from the engine compartment. 
I see this on the front of my carb:



I have a hard hose line in my firewall currently not connected to anything inside the cabin:


The hard hose line has a rubber adapter and it fits onto the carb.  I can feel suction (vacuum) when the engine is running:


In the cabin the other end of the hard hose line fits into the rubber connector on the vacuum selector switch of the dash control unit:



I don't have any of the original vacuum hose lines for the dash control unit - is this the correct hose size and connection method?  If so, I think I'll bulk order 20' of 1/8'' hose.  That length should give me plenty of room to test, make mistakes and trim to final fit.  Does anyone have a link to the rubber connector at the end of this hose?  I'll need to order at least four of them.  I checked to see if it would fit on one of the actuators and it looks like it will work:


Thanks,
Tony

b_hill_86

  • Active Forum Member
  • *
  • Posts: 831
Re: Bring back the factory air on my 78
« Reply #2 on: July 03, 2020, 06:27:28 PM »
I think you can buy those rubber ends at auto parts stores. They’re meant to be used as reducers but I think they’d work. I had some that looked similar to my factory ones.
-Brian-

1977 Trans Am 400 4 speed

TacoTownCharlie

  • Active Forum Member
  • *
  • Posts: 10
Re: Bring back the factory air on my 78
« Reply #3 on: July 03, 2020, 07:06:39 PM »
Thanks b_hill,

It looks like it might this part: Dorman AutoGrade Soft Vacuum Connector Part #47402.

The parts stores I checked around me don't have it in stock but they can order it.  Same deal on the bulk tubing, I can get a 3' section in the store for $5-6 or they can special order it for .39 a foot.  Time to get those wheels turning.

I guess I'll check the two electrical switches on the dash unit and make sure those still work.

Wallington

  • Active Forum Member
  • *
  • Posts: 483
Re: Bring back the factory air on my 78
« Reply #4 on: July 04, 2020, 03:28:28 AM »
Be aware that many of the air con kits are aimed at Camaro models and those that didn't have factory AC at all. Just need to check before you order what you are actually getting and if suitable. If you have any of the stock gear in good condition then that's half the battle of collecting parts. The other half are maintenance parts and should be replaced anyway, much easier now that many parts are now reproduced such as hose assemblies.

firebirdparts

  • Jedi Council
  • Oracle Forum Member
  • *
  • Posts: 18863
Re: Bring back the factory air on my 78
« Reply #5 on: July 04, 2020, 11:46:37 AM »
Sounds like you've got it figured out.  Some of that ductwork is going to have to be junkyard material, I think.  The vacuum doors and whatnot are very reliable, thank goodness.  After 40 years if any of the diaphragms broke you'd never find any parts to fix it.
I want to be like Paul Kenny when I grow up
Joe Bays
1977 Y82 4-speed (red interior)
1978 Skybird 350
1978 Redbird 305
1979 Redbird 301 4-speed
1992 Lincoln Mark VII LSC/SE (red)
1970 Datsun Pickup
1953 Chevy pickup (converted 4x4)
1988 T-bird Turbo Coupe

Wallington

  • Active Forum Member
  • *
  • Posts: 483
Re: Bring back the factory air on my 78
« Reply #6 on: July 04, 2020, 10:56:02 PM »
Some more of those vacuum adapters are 474003 and 474023. I couldn't find anyone who had ever sourced any or tried. These are the style that suit the intake checkvalves, they don't have the locking flap for the vacuum pods, but still work.

I guess you have a 40 year supply of doors and heater boxes to sift through. If you need the parts, that's what you do. You may have to purchase loads of junk before you find a part you can use, but if you don't have a choice.
« Last Edit: July 04, 2020, 10:57:53 PM by Wallington »

TacoTownCharlie

  • Active Forum Member
  • *
  • Posts: 10
Re: Bring back the factory air on my 78
« Reply #7 on: July 05, 2020, 05:40:31 PM »
I've got an order in with Amazon so I should get some of the parts within this week.  I just want to get enough hose and adapters to check one actuator at a time.  So I've got deliveries scheduled over the next few weeks.  I hope this doesn't slow me down too much.  I think I'll use this time to clean up the dash control face.  The outer clear plastic has some scratches and there is a think metal part just behind it that could use some black paint.  I'll post some pictures of that as I go.

TacoTownCharlie

  • Active Forum Member
  • *
  • Posts: 10
Re: Bring back the factory air on my 78
« Reply #8 on: July 30, 2020, 07:28:43 PM »
Soooooo,

As far as the vacuum system goes I'm missing the kick panel actuator, the hose to the defrost vent and, worst of all, the hose to the interior actuator in the heater box.  Just the worst news possible.

Take the dash out (I need the room to work).  Take the evaporator box off the firewall (after taking the passenger front wheel and inner fender off).  I wanted to get to the system fan to test it before I dive into the major AC work.

Wait on parts.

I took this opportunity to send the dash bezel out for reconditioning, shouldn't take much longer.

I now have a hose to the defrost vent actuator and it works.  I have a hose to the interior actuator in the heater box and that works.  I have a kick panel actuator and it works but I need the $13 spring to complete that part of the system.  The cowl vent actuator works OK so I'm going to say the vacuum system is working.  I also checked the heater core, it has recently (within the last 5 years) been replaced.

I did a quick check on the dash control panel electrical connections and cleaned those up.  With those connections made I connected the resister and relay switch on the outside of the evaporator box and checked the fan operation.  I ordered a new fan because it is too expensive to get this far into the AC system and not change that part.  The fan works on all speeds, so more good news.

The only under the dash duct part I had was the defrost vent duct.  The car originally had air conditioning, just all the duct work got lost somewhere.  I found most of the parts on Craigslist in a neighboring state (California) and made a Saturday trip to get them.  Good news, I was also able to pick up a few parts on my bucket list and I made two new Trans Am friends.

So back in Arizona I think I'm making progress.  The vacuum system works, the fan system works and I now have all the duct parts thanks to Ebay and Craigslist.

I'm taking this opportunity to solder the stereo connections and I'm going to try to make a mount or anchor for the stereo.  The original radio had a small metal part to attach the side of the radio to a metal support on the dash.  I still have that part but it won't fit the newer DIN standard.  I think I can get a bracket in there to make everything work out. I also had previously installed a pair of Blaupunkt speakers to the center dash opening using the original speaker bracket.  We'll have to see if that still fits with the AC center duct.

So I think I'm ready to order a new evaporator, condenser and compressor (basically everything under the hood).  I'm looking at the Stage 3 kit from Original Air.  I'm leaning to R134 but if I find some R12 I would seriously reconsider. 

I need to research the kick panel installation; I know I need to seal that area.  I also need to check on adding a second ground to the blower motor, if anyone has a best practice I like to hear from you.

TammyTA

  • Active Forum Member
  • *
  • Posts: 206
Re: Bring back the factory air on my 78
« Reply #9 on: August 04, 2020, 12:30:09 PM »
I was thinking of going the same route that your are, fixin the ole system.  Started adding up the cost to repair/replace parts and it got pretty ugly... I had a '78 years ago & the a/c was terrible, so I opted for the Vintage Air.  I'm just getting started with the install & am pretty happy with it so far.  I too live in AZ, so hope it puts out enough to keep the wife happy.  lol    Of course I'm not gonna expect it to do much in the 117 degree heat like we had last week.   :P

Re: Bring back the factory air on my 78
« Reply #9 on: August 04, 2020, 12:30:09 PM »
You can help support TAC!

 



2020-B1-3