Nick's 1971 Mark III

[LithiumCobalt]

You should be able to isolate the compressor and then disconnect the lines with the valves in place. Then you would be able to put the lines aside. You’d still have to work around them since you wouldn’t be able to remove the lines, but in theory it should be possible. That’s all assuming that the valves are air tight, though, and not seized in the open position. One of mine was really tough to close

[1Bad55Chevy]

Chevy, have you checked out the blower motor resistors?

I honestly haven't messed with it. I can turn the system on and the compressor cuts on and the evaporator gets cold. I can hook power to the blower directly and it cuts on. I have no vacuum lines hooked to the engine besides the booster and vacuum advance so the no air actually comes out of the vents. This is one of my upcoming projects!

[1Bad55Chevy]

You should be able to isolate the compressor and then disconnect the lines with the valves in place. Then you would be able to put the lines aside. You’d still have to work around them since you wouldn’t be able to remove the lines, but in theory it should be possible. That’s all assuming that the valves are air tight, though, and not seized in the open position. One of mine was really tough to close

I wanted to unbolt the compressor from the block and pull the short block out with all the AC intact in the car. With the engine out I can clean, repaint, and install new gaskets!

If the valves closed on the compressor wouldn't you still lose the majority of the charge?

[LithiumCobalt]

You should be able to isolate the compressor and then disconnect the lines with the valves in place. Then you would be able to put the lines aside. You’d still have to work around them since you wouldn’t be able to remove the lines, but in theory it should be possible. That’s all assuming that the valves are air tight, though, and not seized in the open position. One of mine was really tough to close

I wanted to unbolt the compressor from the block and pull the short block out with all the AC intact in the car. With the engine out I can clean, repaint, and install new gaskets!

If the valves closed on the compressor wouldn't you still lose the majority of the charge?

If you close the valves to isolate the compressor, much of the charge should be retained in the evaporator, condensor and lines. All you would lose is what little is in the compressor. So, if you close the valves, it essentially isolates the compressor from the rest of the system. Then you just remove the valves from the compressor and your compressor is free to do what you wish with.

[Lee]

Chevy, I think the design of the Tecumseh/York compressors was such, that liquid refrigerant was designed to not collect there…the “crankcase” held mostly the oil supply. (Later compressors like the A-6 will retain liquid refrigerant, and that’s when those isolation valves disappear) The 3 way valves were designed in the system to allow maintenance, replacement, and oil level checks without losing “much” charge, and that should be only vapor. You do need to evacuate the compressor after everything is screwed back together.

But beware! I tried this once on my Mercury, and found out the hard way that the high pressure valve wouldn’t seal. I think Nick mentions this as well.

[frasern]

All you gain , by removing the compressor is a small bit more room, you still have to work around the hoses etc. I have removed and installed engines, a number of times, without removing the compressor, but not in a Lincoln. Most recently, last year in an '84 diesel F250, it was awkward, but The AC worked just fine afterwards.
Those valves have probably not been turned in decades, they are very likely to leak. If you turn them from time to time, they will remain functional, but who does that?

Just my two cents.

[1Bad55Chevy]

Thats how I typically pull engines out, leave everything hooked up, unbolt all the accessories from the block, and yank it out the top. What I don't know about the Mark is if the high side hose going from the compressor to the condenser has enough slack in it to actually move it out of the way. It looks like a really short hose with almost no movement in it. I know Nick was just fighting with his car pulling the heads off it so I figured he would be the best to ask for an opinion.

I didn't know about the shut off valves on the compressor so I am going to try and turn them. I am absolutely terrified about losing the charge and trying to find a r12 source (is r12 even in production still?). The absolute last thing I want to do is convert it to 134a because those converted systems never perform as well. A vintage air kit would out perform a converted 12 system but the cost is fairly devastating!

Here is another question I have about the system, does the system have a high side compressor switch? I was looking on the hoses today and didn't see any pressure switches on the system.

[Lee]

Chevy, there definitely is a pressure switch with the automatic system (it appears on the wiring schematic), but I'm not sure on the manual version. Don't know which you have...

[1Bad55Chevy]

It's a ATC system. I wonder where it is, only wires I saw on it were the ones that hooked to the expansion valve from that bulb sensor.

[LithiumCobalt]

That high side hose is nearly immovable with it connected as designed. Once you disconnect the valve from the compressor, the hose is able to be moved out of the way easily as it is pliable.

[LithiumCobalt]

R-12 can still be had. Hasn’t been manufactured in, I think, decades? In my old city, there is a professional shop that still has ample supply. I’ve always had them do all of my AC charging.

[1Bad55Chevy]

Chevy, there definitely is a pressure switch with the automatic system (it appears on the wiring schematic), but I'm not sure on the manual version. Don't know which you have...

What schematic did you find this on?

I looked through the service manuals today and all that is shown on the wiring diagram is a "ambient air clutch switch". I guess on the ATC cars it will not turn on the compressor if it's to cold?

[Lee]

It's on the LL diagrams. It's bottom left, just above the ac clutch. It's wired in line with it. This picture may not show it clearly, but you can get it on their site.

[Lee]

Chevy, I just happened upon a tech tip published on Bakers old website. Might be of interest to you:

[LithiumCobalt]

The slabside Lincolns had an icing control switch with a *gasp* temperature-sensing bulb that would extend down into the evaporator chamber. This was the sole compressor cutout in the system. Not sure if that’s the same or changed by the Mark series