Evaporator location/removal

[Jsteencken]

I am looking to restore my 1966 Thunderbird AC system. The previous owner removed the compressor , the condenser radiator and cut the AC lines at the firewall. I assume this is the approximate location of the evaporator core. At the same time I do this work, I will be servicing the engine cooling system and replacing the heater core. I can find lots of info on-line for removing the heater core, but very little on the evaporator coil.
Can someone provide information on exactly where the evaporator core is located and how to remove it. Thank you for any help.
1966 Thunderbird 390 engine landau

[tbird]

Welcome to the forum you will find a lot of assistance when need in this group.

The evaporator core is installed inside the heater box under the dash it will be fun to get at with the dash in place.

Would suggest that you obtain the following printed information to help with any work that you are going to undertake these cars are very complex for their time and not easy to locate all the relays and wiring in them.

Owners Manual (used or Jim Osborne Reproductions)
Thunderbird Shop Manual (used or Jim Osborn Reproductions)
Body Trim and Sealant Assembly Manual (Jim Osborn Reproductions)
Electrical Assembly Manual (Jim Osborn Reproductions)
Wiring Diagram Manual (Jim Osborn Reproductions)
VTCI Original Factory Specifications (VTCI Country Store, available to members only)
These must be for your year of vehicle as there were many changes made from one
model year to the other.
Most of these items should be available from your favorite Thunderbird supply house or
directly from Jim Osborn Reproduction, cost will be about 125.00 plus shipping cost

[paulr]

Welcome to the forum you will find a lot of assistance when need in this group.

The evaporator core is installed inside the heater box under the dash it will be fun to get at with the dash in place.

Fun is an interesting word, Jim.

Welcome. As stated, the evap core is located inside the A/C plenum. The manual outlines a detailed procedure for removing the plenum with the dash in place. It strikes me as a good way to go insane, if it's not in fact impossible. I guess some have done it this way. An alternative is to remove the dashboard entirely, and the guts become much more easily accessed. Removing the dashboard is a significant project by itself. But, if you like taking puzzles apart and putting them back together again, this will be a lot of "fun", per JIm.

Joking aside, you should really consider the dashboard-out method. The core is not the only thing that should be inspected. There's an expansion valve, electro/vacuum compressor switch, vacuum motors and a half mile of vacuum hose to replace (after 50 years, assume it's leaking somewhere--it will).

Either way you go, start by getting the books mentioned above. You'll need a roadmap through this. Best,

[Jsteencken]

Thank You Jim & Paul, the info is very much appreciated. I do have some of the books, but not all. I will pick up the others before I start.
I actually have another dashboard I purchased from E-bay that is in very good condition and with no cracks!! So I think wanting to get the AC working has now convince me of replacing the dash. I will keep the words "fun" and "insane" in mind when I'm curd up under the dash.
Thanks again !!

[jtschug]

I'm in the process of doing exactly the same thing. I removed the dash and the whole box out of the car. I've opened the box up and discovered that at some point the heater core was replaced and during the replacement process some of the fiberglass was damaged. This weekend I will be cleaning and repairing the broken fiberglass.

There are many doors inside the box which control where the air comes out. Some of these doors were supposed to be covered with a thin layer of foam. Most of the foam in mine has crumbled off and rests in the bottom of the box. I'm going to wire brush all these metal parts and give them a fresh coat of black paint, then reapply some new foam to the doors.

For your particular situation, a word of caution. There is a funky device on the side of the box where the A/C hoses come out which has a thin metal tube which goes from this device inside the box and sticks into the middle of the evaporator core. This is a temperature probe, and it is very fragile and very expensive to replace. So don't just unbolt this funky thing and start yanking on it.

To get the evaporator core out you must:

1) Remove the 'accordion' duct on the front of the box
2) Remove the A/C door assembly behind the duct (usually covered with a thick tar-like insulation)
3) Remove the metal top of the box where the two defroster ducts attach (when you removed the dash, be sure to remove the ducts from the box, or they will rip, or perhaps rip the defroster ducts which are attached to the dash.)
4) Now you can see the evaporator assembly. Carefully pull the temperature probe out of the middle of the evaporator core.
5) Now you should be able to gently lift the evaporator out of the box.

While you are in there, I agree that you should replace the vacuum hoses. I think it is wise to replace them one at a time and maintain the color coding because there are a lot of them, and it would be easy to mix them up and cause the system to malfunction. Also you may want to check to be sure all the vacuum actuators work properly. I use a tool called a MityVac which you pump to create a vacuum and see if the motors work without relying on the engine.

[paulr]

... a word of caution. There is a funky device on the side of the box...

Excellent point, though I never thought to call it funky...I think I will now! That is the vac-operated compressor switch right below the expansion valve, and the skinny tube is your capillary tube. "Expensive to replace" may be true if you can ever locate someone to repair it, or find a used replacement. Treat this piece like a winning lottery ticket. There are no replacements.
If yours no longer works, you have an issue. I think JIm M (Tbird) is figuring out how to rebuild them. Otherwise, someone somewhere on this board figured out a way to work around it using refrigeration equipment...can't find that post, but I'm still trying. Best,

[tbird]

Paul have not looked at the repair of the original vacuum thermal control as I do not have one to try the repair on, unless maybe I could take the one out of my 65 and experiment with it.

[RAVEN]

Jim, in simple terms, NO DO NOT DO IT. If you do I will get you committed.

[tbird]

Raven
What I need is a complete switch with a broken capillary or it could be a working switch (except then I would not want to destroy it). Then I think that I could find parts for a do it yourself repair by purchasing available control switch's from commercial refrigeration suppliers and using them to repair the OEM special switch.

Those that have replaced the switch with a off the shelf temperature control switch have only addressed one function of the switch and that is the low temperature cut-out to stop the evaporator from freezing up, if it does freeze the valves in the compressor could break or worst case break the connecting rod worst case. So this has addressed the freeze issue if the correct temperature range of switch was selected, the seconded issue that is not being addressed is the vacuum side of the control this interfaces with the A/C control head in the dash and allows you to adjust the discharge air temperature with the slide control on the head. Someone I believe added a adjust able temperature control with the adjustment knob installed under or in the dash and by passed the control head completely.

[paulr]

Raven

Those that have replaced the switch with a off the shelf temperature control switch have only addressed one function of the switch and that is the low temperature cut-out to stop the evaporator from freezing up, if it does freeze the valves in the compressor could break or worst case break the connecting rod worst case. So this has addressed the freeze issue if the correct temperature range of switch was selected, the seconded issue that is not being addressed is the vacuum side of the control this interfaces with the A/C control head in the dash and allows you to adjust the discharge air temperature with the slide control on the head. Someone I believe added a adjust able temperature control with the adjustment knob installed under or in the dash and by passed the control head completely.

Jim,

You and I recall the same post, but I can not seem to find the right search terms to find it again. It's here somewhere. IIRC, the poster rigged a system that required the driver to manually turn the compressor on and off. This is what happens when there's no vacuum operated temperature control function as set at the control head. Also, when you say "this has addressed the freeze issue if the correct temperature range of switch was selected," you say a mouthful because the installer is required to know temperature range limits, which if unknown could result in a voided warranty (on a new compressor) or general malfunction or damage to an otherwise restored system. One step forward, two steps backward. The OEM switch is preferred because I don't want to turn the compressor on and off as the cabin temperature fluctuates. That's my 2 cents (and Wally doesn't have any more pennies).

[tbird]

Paul
I still got a pile of Canadian pennies will have to take some for Wally when I go to the VTCI International Convention next August so he can have his 2 cents worth.

[RAVEN]

Jim, you forget, in Canada we round up now! Make it a nickle

[jtschug]

I used to design automotive A/C systems, though I retired from engineering in 2008, my last design was the 2011 5.0L Mustang. I also did the 2002 T-Bird, but it was just a slight modification from the Lincoln LS.

More modern designs use a pressure switch on the evaporator outlet line. Since the refrigerant inside the evaporator is a combination of liquid and vapor, pressure is a very accurate way of determining the temperature of the core. If the pressure falls too low, the core will freeze. Ford used a range of clutch cycling switches with a range IIRC from 18 psi, down to 11 psi depending on how far the switch was from the core itself, and how the system performed in testing. The switch screws in to a metal fitting brazed on to the tube with a bicycle type schrader valve that allows the switch to be replaced without discharging the refrigerant. It would be relatively simple to modify a T-bird to use one of these switches. It may require a relay because I'm not sure of the electrical load of the old clutch system.

Temperature control is A/C mode in modern cars is done with the heater core. Basically in full cold A/C none of the air goes through the heater core, and there is a 'blend door' which diverts some air across the heater core to get more warmth, even in A/C mode. The 2002 T-bird does not work this way, but don't get me started on that....

Last week I talked to someone at Classic Auto Air in Florida. He told me they stock almost all the parts for these old birds. I don't need the clutch cycling funky contraption, so I didn't ask about that specifically, but it sounds like they have everything anyone might need to fix the A/C with tested good used parts.

[paulr]

Yeah, CAA does have everything except the funky switch (and cap tube). At least, over a year ago when I last dealt with them, that was true.

[jtschug]

Repairing a capillary tube like this would be a bit like making a neon sign. You've got to charge the tube with gas and then weld it shut. It might be something like R12, Which is almost completely liquid at reasonably cold temperatures, say 0°F, so you could get the whole room really cold, including the switch and everything, then measure out just the right amount of liquid, probably a drop or two and get it into the assembly before welding it shut. Of course air and humidity could mess up the function, so you will need to vacuum it out before inserting the liquid, and determining exactly the right amount of liquid/gas is also key. Perhaps if we knew how they made it in the first place we could figure out how to rebuild it.

Mine says it was made by Ranco, and they still make capillary tube temperature switches. Perhaps we could arrange a factory tour or something or talk to someone there and find out what is possible.