A/C Troubleshooting on '82 SC

[wazzz]

no clue, but it should be a 4-pin connector.

[francesconyc]

Originally Posted by wazzz

no clue, but it should be a 4-pin connector.

thanks, will investigate

[francesconyc]

I nought and installed a new front cooling fan, and I was hoping to celebrate and close this thread after I discovered a missing fuse in the smuggler box but.... I still have to investigate the jungle of wires I found inside the smuggler box.

I discovered that PO (or their mechanic) added two fuse holders and another relay...

I replaced the broken fuses today and weirdly enough one of the fuses made the alarm beep, then I added the second fuse and the horn started making noise... what the heck.. (maybe going to the notorious Ungo Box TL-3000???)

I don't understand what kind of hack they did and for what reason.

So hers; my plane:
- remove the fuse holder/connectors
- remove the additional relay/switch whatever it is...
- and connect everything based on the Bentley diagram.

I think I found the wire coming from the fuse 20 to the squared-bosch-relay (pin 30)
but I don't see any yellow and black wires (pin 85 and 86)... yet...

Next to test continuity between:
-Fuse 11 to Relay 85
-Fuse 20 to Relay 30
-Relay 87 to Switch C red wire
- From starter to Relay 86 (this one I have no idea how..which is the wire coming form starter?)


What do you think?

[francesconyc]

ok it seems all the mess is due to the Ungo Box TL-3000

at this point I guess I need to completely remove it and reconnect the wires to the squared bosch relay

Im not sure why in the hell the PO had the alarm system use the same wires going to the AC relay!

[kuehl]

Originally Posted by francesconyc

ok it seems all the mess is due to the Ungo Box TL-3000

at this point I guess I need to completely remove it and reconnect the wires to the squared bosch relay
!

Your back on the right road

[francesconyc]

success.
but this is emberassing because I was testing and looking at the wrong relay. all the wire jungle was the UNGO alarm wiring.
The broken relay was hidden behind, next to the evaporator motor, an old metal small cube, attached to the body since 1982.
I removed and replaced it with a new bosch.

now all the electrical part works. The evaporator fan works. brand new cooling front fan works. i get a nice push of air in the cabin.
I still haven't tested driving around yet.


NOW.
last thing to check is to connect back the clutch on the engine ebay. I was told that I should hear a click or something?
After that, I need to refill the freon.
the container on the driver's fender is a Khuel, so it must have been replaced relatively recently. but I don't see any white ball floating

Im thinking of buying some new old stock freon from eBay, what do you think? or the new refrigerant may work as well? can I do it myself or is better to go to a shop where they have the machine (and cost of $300)?
I also ordered from Amazon the AC pressure gauge kit.


anything I should no before proceeding?

[kuehl]

hmmmmmm.... in general terms of basics:

The best AC vacuum pump, in theory, at sea level, might pull down to 29.921 inches of mercury (inHg). In Denver, 5,280 ft you might pull down to 24.9 inHg.

And, in terms of the reverse or vacuum, 29.921 is 14.70 psi of pressure.
Hence, a system vacuum leak test only tells you if you have a 'gross' leak; aka
you probably are not missing an O-ring (it happens) or you did not forget to snug
up all the fittings.

Depending upon outside air temp the system 'static' (ac comp has not run for awhile) pressure with R12 could range from 9.2 psi at 0F to 117 psi at 100F.

In a decent running system, at idle, the low side pressure, typically, can range from 20 psi to 40 psi; the low side pressure reflects the temperature of the gas in the evaporator core. And, the high side pressure can range from 100 to 300 psi out the compressor. Vent temps can range from the 30's f (you evap core is probably below freezing) up to 60 f (you got problems or you got the doors and windows open or you got other issues). In a perfect world it all depends upon the ambient outside air temperature around the car, condenser capacity, amount of refrigerant, your equipment is working properly and you've 'ben there done that' enough times.
Everything is relative to 'temperatures and pressures'.

Analog (dial and needle) gauges are only are as good as their quality and whether you have your reading glasses on or are looking at the needle and hash marks on the dial directly (perpendicular).

"Air" (a mix of nitrogen, oxygen, argon, etc) and refrigerant do get along well. Air increases the pressure in the system. Less 'air' in the system the happier it is. Water (H2O, or moisture) really messes things up; blocks things up.

The first objective after doing a gross vacuum leak check is to get all the water out of the system by vacuuming; evaporating, boiling it off and out of the system.
At sea level with 32f ambient temp water starts to boil off at 29.90 inHg. At 104 f it boils off at 27.83 inHg.

Assuming you got too much moisture in a system, and you got a good vacuum pump, things are tight, you can pull a vacuum below the boil point and end up freezing the moisture. Yup! You could have thought you pulled all the moisture out but instead you left ice in the system that will come back and haunt you when it freezes inside the expansion valve (TEV or TXV), or in the line between the drier and TEV and can't figure out why the high side PSI is too high when you have an amount of refrigerant in the system that is less than what you know it should have. Ditto with air in the system; air will push up your pressures when mixed with refrigerant.

Many experienced AC technicians who service cars and never have issues probably work mostly on cars with engines in the front of the car. But when they take on their first "air cooled" classic they are stumped; their first point of 'blame' is the TEV (wonder why?; its air or moisture). Front engine cars have all the AC components in the front trunk while our air cooled classics only have the evaporator box in the front frunk. Front engine cars have 1 condenser and an average of 12 feet or so of AC lines. The classic air cooled has 2 condensers and nearly 40 feet of AC hose; and then you have the drier, evap and comp naturally. So.... if you wonder why pulling a 'vacuum' for 30 minutes or the "over night" crowd runs in to trouble.... just remember what you are working with.

So... the key tool in vacuum is a 'micron gauge' that reads vacuum in a finer scale and shows you things you cannot easily see. And, it helps to have a bottle of nitrogen to purge the air before hand..l... but all of this is not commonly used but it all makes sense later.

If you run into issues during the evac, charge and test, toss in a new drier. If you have o-rings in the system, replace them. If you have to replace parts, put back in refrigerant oil that is lost when you put in a new 'drier/dryer' or other parts; use this as a rough guide for replacing parts in a not so perfect world: an entire system factory 2 condenser system, if new, needs 5-6 volume oz of oil; less and you can damage a compressor, too much and worse case the evaporator core be a bit warmer. Figure, roughly: a drier needs an ounce, a rear condenser an ounce, a compressor 3 ounces, evap and ounce, hoses 3 ounces; yes if you add it all up its more than 5 to 6 but better safe than sorry when you have a compressor grenade on you and toss its cookies and you end up spending 12 hours cleaning up the cookie monster's party.

In the mean time you have done, I will say, an amazing job of hanging in there and working through the electrical issues. ***** five stars, A+ , a thread to remember.

Tally Ho!

[francesconyc]

Lesson learned is that along with the Bentley you need to know if the PO messed up with the car... ugh.

so in conclusion, are you saying that a regular AC technician (not porsche specialist) may not understand/not capable of recharging the AC?


i bought eh AC gauge just to test the pressure I was told. i see a lot of cans sold on amazon/ebay, is it something doable at home or not?

and yu said better overcharge a bit more of freon than less correct?

[kuehl]

Briefly.
1) There is a learning curve of sorts when evacuating, charging, testing and troubleshooting.
How deep you dive in, how long you can stay tuned in determines how well you will do.
2) There is a pre-requisite of tools you need, an investment of sorts depending how long you are in it for the long haul.
3) Some have no problems. Others struggle.
4) If you feel you want to have an AC tech handle it:
a) they have to have worked on air cooled classic 911's or 930's
b) they are probably going to be as older than me
c) you will have to pay them for their time; if you see a sign on the street corner
that says something like "Get your AC fixed for $89.99", do NOT stop your car there.
By the way are you sending me Bit Coin, are you paying in Becks beers (cold please),
or how many Mulligans' are you giving me on the 1st tee box?

Some memorable members posts can be found by searching post user names:
Discseven
GH85Carrera
mthomas58

and many, many more other members post, a blessed bunch of good guys,
I have learned much from.
And there is wild willy.

I'd suggest reading a bit, says us repeating key strokes, and it helps to read

https://forums.pelicanparts.com/porsche-911-technical-forum/834136-my-ac-burns-me-up-summary-fix.html

https://forums.pelicanparts.com/porsche-911-technical-forum/397009-c-upgrade-project-starts-tomorrow.html


Forgive my sins for I did not know the rules.

Sooooo many great post and anecdotes.

[francesconyc]

Thanks very thorough! I'll read everything. im not in rush to fix it and I love learning something new.

What I know is that PO installed one of your drier Khuel, and installed a new hose line from compressor to the front (need to double check). I would guess AC was working well than, and probably already verified for leaks. PO also gave me some refrigerant connectors so I believe he was rechargin it by himself at some point

[GH85Carrera]

I have posted before, it is physically impossible to have "to good of a vacuum" the lower the microns, the better. And as mentioned above, ice can and will form if you just pull the vacuum once.

I use a nitrogen purge with a AC nitrogen rig. It puts in nitrogen at any pressure you want, but I never go more than 150 PSI. I do a vacuum, nitrogen purge a couple of times before a final long (2 or 3 hours) vacuum pull with fresh oil in the two stage pump over a two day process to be 100% sure there is no moisture left.

My system is all Griffith's Mr Ice system, and I can go for years and not touch the system and I use my AC a LOT. I never roll the windows down and after 29 years of ownership, I have opened the sunroof three times, I use heat or AC if I am driving. And 10 to 12 hours of driving in 100+ temps I get 37 degree air blowing out the hurricane blower and I sometimes have to back off the cooling because I get cold in triple digit temps.



When the return hose turns white from the frost on it, I know my AC is Mr. Ice cold.

[francesconyc]

here my AC
dieri seems empty or at least I don't see the famous white ball.
The AC bottom line looks new, replaced few years ago I think.
I 'd assume there are no leaks. since the system has been serviced.
Is the last part to do just rechargin then?