What's the secret to getting a 70 heater box out

[Dan LeBlanc]

So I'm crazy and replacing the evaporator on the 70. Let's get that out of the way first.

I've gone through all the steps in the FSM so far except the two screws that hold the vacuum harness in and removing the mode selector behind the fuse box to disconnect the vacuum harness. The heater box seems stuck. I've removed 7 screws from the heater box (FSM says 6).  The box is somewhat free. Are those two harness screws threaded into the firewall?  I thought the bos would at least be free by now.

[Scot Minesinger]

Dan,

I have repaired climate controls from 1965 thru 1982, and 1969/70 is the most difficult for that reason, plus removal of dash control unit by light switch (do not be tempted to just install the bottom two screws, or you break off the bottom two screw foundations).

There are four screws that are hard to get to on inside of car two on either side of heat diffuser above drive train hump (hi/low).  Those have to be removed.  I have removed two of these systems (what you are going thru) and each time it was not fun.  Also, as I remember (back to 2013, last time) I did remove the two screws that held the vacuum harness in.

Scot

[Dan LeBlanc]

Thanks Scot. Those must be the ones that hold the mode selector on (whatever that is according to the FSM)

[Scot Minesinger]

The four screws that hold the box over the hump inside the car under dash that receives the airflow from inside the engine bay and directs it to either floor dash or defrost.  That must be removed.  It has those two small vacuum actuators attached to it.

[Dan LeBlanc]

Ugh. That's what I was afraid of. What a spot to get at.

I walked away from it before I took out the sledge hammer and took out the heater box in pieces (patience is a virtue I wasn't born with).

Tomorrow is a holiday and a new day here. I hope a good night's rest will be what I need to finish it off.

[Scot Minesinger]

Dan,

Going back to your original post unless the evaporator is leaking or otherwise compromised, I would not replace it. 

If you are going to no matter what, then you should also replace the heater core.  The heater core is protected from galvanic corrosion by paint that separates copper from ferrous metals, crazy.  The most common failure is the paint flakes off.  The core is like $50, and you see how difficult it is to get to, so might as well.  Or, at least improve on the paint shield from galvanic corrosion.  I use Felpro blue gasket material folded and cut just right so that no copper and ferrous metals touch in addition to the paint.  It is a tight fit.

Also, while the heater box is out, might want to replace that vacuum actuator on heater box that dumps airflow into engine bay until car warms up.   Again, $30 and you see what it takes to get the heater box off.  Alternative rig a cable or something so you can maneuver the damper to not blow into engine bay in case actuator ever does fail.

[Dan LeBlanc]

The evaporator isn't leaking but the POA valve is stuck open. I thought it would be wise that if I'm opening up the system I might as well replace absolutely everything.

Never thought it would be this bad.

[Dan LeBlanc]

It's all out. Evaporator housing is cleaned up. New evaporator in, POA and expansion valve done. Liquid line is installed. New tape on the expansion valve bulb. All ready to reinstall except the new suction hose fitting doesn't work. Called Old Air and a replacement is being sent today. They tried it on the same Delco expansion valve that I have to make sure it works and it does. New fan motor as well. Air flow should be much better between the new fan motor and non clogged evaporator.

["Cadillac Kid" Greg Surfas 15364]

Dan
With the evaporator that plugged I imagine you weren’t getting too much airflow in either cooling or heating mode.
Greg Surfas

[Dan LeBlanc]

You got that right Greg. It always felt a little weak. Now I expect good air flow.

Just ordered a new heater core. As far as the door goes that diverts air to the engine bay when the car is cold, that actuator is good for now but I may just put a small screw there to disable that function in case of future failure.

["Cadillac Kid" Greg Surfas 15364]

Good call. I did that to my 70 and never looked back. Ran that way for 10 years m
Greg Surfas

[Dan LeBlanc]

I may separate the two halves of the evaporator case again. I don't like how well its sealed. We have 440 tape (glazing butyl tape) at work that I can apply in place of the old dum dum. Two 1/8" layers should be enough to compress when I reassemble again.

I also did new foam evaporator seals and a rubber drain. When I say everything is going to be new, I mean EVERYTHING.

I'm very excited to see how well the new Pro6Ten will work. I called Old Air this morning and explained I could only get 100 of the 220cc of PAG oil out of the compressor. They say add 7oz of Ester all in the compressor and let it distribute where it needs to. I don't like that but that's their advice on their compressor.

I would've liked to have had all 11oz of pure Ester.

["Cadillac Kid" Greg Surfas 15364]

Dan
What refrigerant are you using?
Greg Surfas

[Jeff Rosansky CLC #28373]

From what you have seen, is there a "simple" way to clean the evaporator/heater core WITHOUT (key word there) going thru what you did?
Also if I may ask, that door are you referring to? Is it the one on the left center of the firewall? I have an occasional issue where I get warm/hot air coming into the cabin and I am trying to find out why.
Thanks ks
Jeff

[Dan LeBlanc]

R12. 4oz of PAG oil mixed with 7oz Ester combined with R12 worries me.

[Dan LeBlanc]

Jeff. That's the one. Absolutely impossible to get the evaporator housing out without taking out the heater box. Now way to get to clean the evaporator through the blower opening. 

["Cadillac Kid" Greg Surfas 15364]

Dan
You are right to be concerned. You would have quite an unholy mix. Things like miscability and oil return would be a crap shoot.
Greg Surfas

[Dan LeBlanc]

If that's the case, should I add the same 100cc I took out in Ester oil. Mix it up by turning by hand. Drain. Measure. Repeat a few times?

If I know the total compressor capacity is 220cc and I keep track of what I add and drain over the course of four "flushes" I should have a good idea of what's in the compressor after the final drain and then bring it up to the level in the FSM

["Cadillac Kid" Greg Surfas 15364]

Dan,
If the compressor has a drain plug on the sump, what oil you should be able to drain out should be all that is in the compressor.  When you add oil, and I am assuming you have or will add it in accordance with the distribution indicated in the FSM, if you are using R12, mineral oil is really the best for oil circulation.
A total of 10ounces with 5 in the compressor, the be sure and rotate the compressor a couple of dozen times to prime the oil pump and lubricate the seal.
Greg Surfas

[Dan LeBlanc]

I'm not using another A6 but rather the Pro6ten replacement.

I described to their tech support what I did to drain it. The slip in the box said it was shipped with 220cc (7.43oz) PAG oil but I only got 3.38oz out. My concern is over the potential 4.05oz remaining in the compressor.

There is no sump on this compressor.

Their tech support said that there would be some residual in the compressor. 4oz seems like a lot of residual. According to them I drained properly.

I'm a bit confused as to how they say it has that much oil in it but only half of it came out.

Ok. Maybe I'm more than a bit confused. They said add 7oz Ester for my system with all new components and call it done.

My drain procedure was remove the two port plugs. Suspended over a bowl overnight. Next morning. No drips. Removed the side drain plug. More came out. Removed the rear drain plug. More came out again. Energized the clutch. Rotated by hand and even more came out.

Maybe I'm overthinking this?