Question about non a/c vs a/c heater box

E

Ernie

True Classic
Ok. Realized I committed the sin of changing topic in Todd's thread about where all the connectors connect.

Here's my question that didn't belong there:

"What's the reason for changing heater boxes? I recall Carl mentioning it from time to time.

I have a friend who would like some help making his '77 road worthy again. I remember working this car maybe 10 years ago and it had an a/c radiator (condenser?) but no a/c components in the engine compartment.

Just wondering if we'll need to add a different heater box to the to-do list."
 
The difference is that the AC heater box has an evaporator and a heater core, where the non AC car only has a heater box with a heater core. Do you need to change it, no. The heater core in the AC box will still work and supply heat to the passenger compartment.


TonyK.

Grimsby Ontario Canada.
 
I can't say if this was the reason for Todd to remove the AC version, but one drawback to it is the vacuum actuated controls for the functions. It tends to leak vacuum and not work as well as the mechanical controls on the heat only box. Also if you are looking to remove every bit of weight from the car, the heat only box is lighter than the AC/heat box.
 
Vacuum actuated controls? Hadn't any idea.

Thanks for the replies. Good this came up now, as I had asked him to reinstall the dash before I get started. Now I will have a look myself while the interior is still apart.
 
Dr.Jeff said:
I can't say if this was the reason for Todd to remove the AC version, but one drawback to it is the vacuum actuated controls for the functions. It tends to leak vacuum and not work as well as the mechanical controls on the heat only box. Also if you are looking to remove every bit of weight from the car, the heat only box is lighter than the AC/heat box.
Click to expand...

I tried to keep the AC heater box even after removing all the AC crap I could, the vacuum system didn't work. Instead of trouble shooting a vacuum system I found a nonAC box and asked Carl to point and tell on the change. It took less than 3 hours to remove the AC box and install the nonAC box including removing the dash and passenger seat. Too much practice on the last 3 removals.
 
Todd, you have undoubtedly saved me some headaches. If you had trouble reconnecting everything after spending a day with Carl, I can plainly see how befuddled my buddy might be when I asked him to put the dash back in. I'm positive it's been out for more than 5 years.

Knowing, now, about this heater box issue is another reason to do it myself.
 
The non AC unit has only mechanical switching, the three cable slide switches. The AC system has a bunch of vacuum operated switches.
The AC system has a water valve that is apparently no longer available and if you did have one it's almost impossible to get to. The non AC valve is available and rather easy to access.
The AC heater box is bigger.
You could certainly leave the AC box in even if you deleted all the rest of the AC stuff.
The white X I had, had a DIY hybrid system with controls from the AC and non AC setups and it didn't work anyway so I ripped out the whole mess and installed a pure non AC system, including the complete conversion under the hood.

Todd scared me a bit when he pulled out his sawzal to help get the AC heater matrix out of his car but we did a finger count afterwards and we had all our digits although one of Todd's hands was still in the car.
 
Hey Todd, If the AC heater box is still in usable condition, are you willing to sell it to me and how much if you are?
 
The AC box uses vacuum to operate a vent, the vacuum serves no other function. If my memory serves the vent is to the two vents at either end of the dash. (These vents are not open to fresh air as the same vents are on non AC cars. (There are plastic block-off plates installed.) Everything else (fresh air & heater valve) are cable operated. Seems like a lot of complexity to operate that vent flap when a simple lever/cable could perform the same function.

The big difference between the two types of boxes is the fan. The AC box has a squirrel cage fan, the non AC box has a conventional(?) fan blade. My guess is the squirrel cage fan pushes more air, and is quieter?

Another difference between the two systems are the control levers. The early 1300 4spd cars had cables operated by metal levers mounted in the console. The later 1500 5spd cars had plastic levers operating the cables mounted up in the dash. These levers broke quite often, especially when the heater control valve stuck. (Hint, hint folks who can print parts!) The metal levers are quite robust.
 
When I had to hook up the three cables on the 77, it was like sticking my hands in a bucket or red ants and really angry yellow jackets.
 
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