Pelican Parts Forums - AC Redo

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- - AC Redo – Some Questions (http://forums.pelicanparts.com/porsche-911-technical-forum/906904-ac-redo-some-questions.html)

Any thoughts on condition so far ? I see some discoloring and dirt but no scratches or grooves to the touch. Not sure if I'm seeing any wear ? Pistons all seem to move easy with no friction felt. Still need to split the case ? Any expert opinions ?

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Evap housing is put back together. I used AC Foam to build an air gasket around the intake openings.

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Inserted the new copper thermo guide tube on about a 45 angle, It stops about 1" from the bottom of the Evap and is 2.75" from the tip to the black line.

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Q: What are these two wires in the smuggler box ?
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Separate the compressor's 2 center case halves keeping the shaft and pistons in the front section so you can actually see at least half of the pistons entire circumference as well as get a better look in the bores; you will need to do this anyway to replace the center case o-ring seal. Makes no sense to do a half xss inspection, you never know what you will find.

Can't tell for sure based on the pictures, but it appears the black vulcanized rubber coating might be De-laminating from the steel reed valve stop plate, or that could be refrigerant oil (wipe it off and check).

The 2 wires might be for the 'horn alarm' which would be mounted over the cross member.

Food For Thought
Picture below was taken 4 weeks ago at a well known restaurant in the city.
This parasitic worm was found embedded inside the cooked catfish.
The Chef was not aware that he should be inspecting all the fish he serves to his clients on a glass plate illuminated underneath with a bright light (prior to cooking).

Now you know how to inspect compressors as well as fish.

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No doubt in some cultures that worm, once cooked is a delicacy in some cultures. I would pass however. Be real glad it was not sushi !

Okay, now post some pictures of the circumference of the pistons.

Can't tell by the pictures for sure however you might be developing some linear wear
in the cylinder bores which over time will lead to a drop in pressures.

You can't expect aluminum bores (non plated) with aluminum pistons to last forever.

Appears the piston' molybdenum coating (black/grey) looks pretty good with the exception of a few scores. If the score lines match up with scores in the cylinders then sooner or later you will lose pumping capacity and debris will develop in the system.

Good work so far!

Now, get yourself a 5x magnifier or jeweler's loop and exam the residual oil in the compressor body.
Black or grey matter can be either the original factory hoses starting to deteriorate or molybdenum,
I guess to say if you find dark color its the factory hoses based on the density color (black) on the pistons.
If you find 'silver' or fluorescence ("sparkling") its aluminum; compressor is wearing down.

[/QUOTE]Now, get yourself a 5x magnifier or jeweler's loop and exam the residual oil in the compressor body.
Black or grey matter can be either the original factory hoses starting to deteriorate or molybdenum, I guess to say if you find dark color its the factory hoses based on the density color (black) on the pistons.
If you find 'silver' or fluorescence ("sparkling") its aluminum; compressor is wearing down.[/QUOTE]

I filtered the oil and fluids drained from the system with a coffee filter. I'm pretty sure the bulk of the black is from the deteriorating hoses- I cut one hose open and the inside was slimy and definitely breaking down. No noticeable metal/aluminum found but it's hard to tell for sure.

I honestly believe the compressor has some life left. Bottom line: If I was just replacing the compressor, I would probably feel fine using this one. But, since the system is basically new, I'll go the safe route and put in a new one.

The front condenser is reinstalled along with the re-finished safety bar, cage and steering rack skid plate.
Evap has also been reassembled and installed.

Almost done.

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just curious,
If I was to upgrade to r-134, does our host take a lot of the guess work out and sell a kit to replace everything that would be impacted by this upgrade, or do I need to figure out all the parts myself?

Rich

Quote:

Originally Posted by r_towle (Post 9503141)

Call Griffiths, he will advise you on what you need.
https://griffiths.com/

Quote:

Originally Posted by r_towle (Post 9503141)

R134a is not an upgrade, it is simply a common alternative refrigerant for the older R12 refrigerant.

Upgrades would be things like:
A better: front condenser, additional fender condensers, evaporator, blower motors, barrier hoses, maybe evap fan speed control, vents.
What upgrades you need depends upon your climate, personal needs, car color, a cabriolet (convertible) needs more AC than a coupe, a black car is more difficult to cool down than a white car, the ex girl friend in the seat next to you can really cool things down, however an ex wife can .... well, you get the idea; you can say what ever you want thanks to Donald!

Sometimes we do an upgrade on a component if the original component failed, say like an evaporator; going from old tube and fin to serpentine.

The minimum requirements to 'convert' to R134a, and if you are thinking about this it is usually because the system is out of refrigerant or it has leaks, would be ester refrigerant oil, a new drier, R134a charge port adapters. However, this approach brings into question "what could I have missed", or "how long will it last". You'd want to replace all the o-rings in the system because the old ones are typically hard and fragile.
If you have debris or old "waxed R12 refrigerant oil" in the system its just going to circulate around and potentially block the expansion valve or damage the compressor. This brings up the procedure of "liquid flushing" all the hoses, condensers, evaporator with TEV (expansion vavle) removed. Liquid flushing involves using an AC friendly liquid (particular solvent) and air to attempt to push the debris out of the components. Then you have to think about the time involved. For example to properly liquid flush the hoses can take up to 10 hours plus about $100 or more in materials and equipment. If you are flushing the old stock non barrier hoses they will still have the character to leak or permeate refrigerant; there goes the new R12 or R134a frigerant and all the hours you spent learning how to evacuate, charge and test the system.

Think about fixing the AC just like fixing your engine. You got 1 bad valve guide, are you going to drop that engine, tear it down and just fix the one guide? Or, you have a bad rotor and pads on the RH front side, do you fix the RH side or both sides?

So, first thing you want to ask yourself is how critical is a good working AC system to you and what kinda of budget you can work out. Get out the pen and paper, a six pack and ponder it.

for ramp , I was wondering how your ac project turned out on your 1987 911 from 2 years ago. I am considering doing a similar upgrade and wanted to know how much difference in temperatures you got with your new system not using the fender condenser.

Quote:

Originally Posted by GH85Carrera (Post 9046470)

If your compressor is the original 30+ year old unit I suspect you will get a few months of use out of it before the nose seal blows or the entire compressor gives up. They are not cheap, so it is a tough choice.

As for the hoses, if they have not been replaced, you can just pull them and take them to a local AC specialist shop and they will re-use the old ends and replace the rubber hose. That only works if the threads are in good shape.

I bought the dual condenser, new evaporator and hoses for my AC improvement. That was 10 years ago and it is the best thing I ever did for my 911. I can drive it on any hot day and be comfortable.

Good luck with your rebuild. It is rewarding to have decent AC.

I don't often quote myself in a thread from a post on the first page. But it looks like my prediction was correct. The original compressor is worn out. You might get lucky and get it rebuilt and have it last a while. Don't bet on it. I am betting you will end up buying a new of manufactured compressor.

Good luck.

Quote:

Originally Posted by john eifert (Post 10194175)

In short, disappointing. With the top down, it's useless. With the top up, it helps but is not nearly as cold as it should be but I think the bigger issue is the lack of air flow. It's on my list to get back to it and see what can be improved.

Interesting though is that I recently bought an '86 928 - after some minor work on that, it AC works fine. The 911 system is simply not designed well.

Quote:

Originally Posted by Ramp (Post 10195214)

Ah some useful and honest feedback. Not easy to share after your hard work. Makes me think about Johnny’s electric AC solution down the line.