AC hose leak

[thysonsacclaim]

Today whilst fiddling with my car and the other issues I posted about, I noticed a plume of 'smoke' coming out from under the hood. I quickly popped it open and noticed the source: white foam-like material coming from a small hole in one of the AC hoses. Oh dread!

This, I assume, was the coolant (probably R12, MAYBE 134a) and oil leaking out of the system. I shut the car down, but not much I could do.

Question:
The hose in question was a rather small one and lead from the AC drier receiver (located in the front of the vehicle, near the evaporator and cooling fan) and into the firewall near the steering column. What is this hose called? I can't post a pic atm because it is dark outside and started raining heavily shortly after this occurred (gotta love hurricane season).

This isn't imperative. There are more important issues to attend to, but I would like to get the hose replaced, but I can't figure out what it is called. I have looked in the manuals, but so far, to no avail. I couldn't find it on autohausaz either.

I plan on replaced the hose and the AC drier receiver, seals, etc at the same time and probably converting to R134a, if it doesn't already have it. After all, the drier receiver is cheap anyway (some $18 bucks I believe).

But this brings me to

Question 2:
I posted a picture earlier of an outlet on the AC drier receiver which had nothing plugged into it. After looking at autohausaz, I see that these are switches. One goes to the fan... but where should the other one plug in?

I'm not sure if this system has it, but some have a high pressure switch which will shut down the compressor if the pressure is too high. If that is the case, then this switch not being plugged in may have caused my AC hose rupture. So, before I spend money on parts I'd like to make sure that it is properly plugged in. Here is a picture. The suspect outlet is in my hand.



I will look around some more to see what I can find and post it here.

[thysonsacclaim]

If I have read this correctly, http://handbook.w116.org/Climate%5C83-530.pdf , states, on page 2, that the top switch outlet is the temperature switch and the lower one is the pressure switch.

If this is the case, then there is a problem. Currently the bottom outlet is plugged into the cooling fan. If the top outlet is indeed the temperature switch, then the fan should be plugged in there, correct?

And for the lower outlet... removing the plug and plugging in the fan to the top outlet leaves it with nothing plugged into it. I am looking at the pictures, but as they are black and white, I can't see where I should be looking for another outlet.

If I am right, the cooling fan being plugged into the pressure switch may have caused the hose to burst, correct?

Can anyone confirm my findings?

[KenM]

You're pretty right with your deductions there, the top switch is the temperature switch, this cuts in the auxillary condensor fan in front of the daiator, the lower switch is the safety pressure switch that cuts out the compressor at about 2.6 bar pressure. The hose line you have going from the drier to the evaporator inside the car is the liquid refrigerant line to the evap. This is the high pressure side of the system so not surprising she blew if the pressure cutout was bypassed and the auxilary fan wasn't running. Not sure where the wiring for the pressure switch should be but it's possible that you are supposed to have the drier without the pressure switch and the wiring is simply not there, someone may have hooked the wiring for the temp switch into it by mistake. Sounds like you might get lucky and cut out the leaking section of hose ans splice it to get you going, could save a lot of fishing around in the guts of the indoor section, nasty....

[oscar]

Like Ken says that leaking hose goes from the drier but connects to the expansion valve, which is attached to the evaporator.  Not trying to correct you Ken on specifics, my main point is it's a real prick of a thing to remove from the expansion valve.  There's just bugger all room to swing a spanner and if it's attached tight, which it will be, you have to be careful not to twist the expansion valve and damage it's connection to the evaporator.  My original hose was perished beneath the battery tray from presumably battery acid(RHD cars except 6.9s have the drier on the RHS).  The first replacement I was too rough with when extracting it from a wreck and stretched it in the process.  It developed many leaks.  The second one from another wreck I was much more careful with and it remained leak proof.  Yet another link or two for you.  In the  link below, scroll to transilvana's post.  It shows pics exactly where and how to get at the expansion valve side of this line in a LHD car.
http://forum.w116.org/mechanicals/ac-system-replacement/msg61270/#msg61270

For RHD cars (not sure about RHD 6.9s) the line is still accessible in the same way behind the instrument cluster.

Slighly left field here perhaps but my 350 never had a temp switch or pressure switch.  There was no hint of a fan ever being installed nor hint of wiring for either switch but I installed a fan a few years back from a wreck and it runs whenever the compressor is turned on as per the instructions of the refrigerant manufacturer whos gas I used.  It's a hydrocarbon gas, different from r12 and r134a.  It's a 4 page thread and if nothing else you can just look at pics but I found it interesting particularly in relation to recommendations in replacing this leaking line.  Rather than experiment with used lines which are an unkown factor, it may be cheaper to take the old line in to an engineering/hydraulics shop and they'll be able to make up a hose.  I recently did the same with a steering hose.  Cost was $90AUD.
http://forum.w116.org/mechanicals/ac-setback/

[thysonsacclaim]

For anyone else with this problem:

Having the A/C fan plugged into the wrong slot (in my case) seems to make the fan run all the time while the engine is going. The correct behavior is for the fan to turn on and off as needed. I'm not sure who did this or why on my engine, but obviously it could happen to someone else. The fan running all the time shouldn't affect anything, in theory, but of course, if the proper use of that switch is to shut the compressor down when a certain pressure is hit, obviously the fan won't do this!

Still not sure about the unused plug/pressure switch. I can't see anything. Unfortunately, several wires in my bay have been cut and/or painted over with gold, so I can't see what goes where. Going to have to check the diagram and individually test all the wires that had a hack job done on them.

Slowly resurrecting the wiring, though. It was (as you say down yonder) quite 'cactus!'

[koan]

The top switch is for fan control, usually operated a relay.

The pressure switch though as far as I know is a low pressure cutout that stops the compressor clutch pulling in if gas as been lost.

koan