AC resurrection and questions

WAID

Full Access Member
Joined
Jul 3, 2018
Posts
134
Reaction score
154
Location
PDX
Working on restoring the long dead AC system on the truck today. AC went out on my parents around 1992. Mom and dad took it into a shop to have it checked out and as far as I know the shop filled it back up with R12 which promptly leaked out over the next week on a camping trip to eastern washington. Dad wasn't one to spend money on such luxuries on what was primarily a dump, firewood, etc run truck and it sat empty. My wife and I apparently being soft and spoiled and using the truck to haul our camper would like A/C working again.

So today I started on vacuuming end evaluating the system. I plan on converting to R134a and using whatever I can on the system(have dryer, o-rings, conversion fittings, and ester oil). I have the system under vacuum now and it seems to be holding -30 in hg with my cheap harbor freight gauge and pump. There is some possible signs of oil leakage around the compressor seal so I am thinking that may be the issue but I am new to trouble shooting A/C and the dirty oil may well be from something else. So after putting the system on the vacuum pump and letting it sit for 15 minutes so far(will wait longer to see but results are better than expected).

Would the compressor seal leak but allow the system to hold vacuum? I see a few have replaced that seal, is it worth going that route vs replacing the whole compressor? I want to do this as cheap as I can but would rather end up with something that will last for a while.
 

gnathv

Full Access Member
Joined
Oct 18, 2007
Posts
1,048
Reaction score
522
Location
Athens, Al
That’s what mine did. Hold vacuum fine but under pressure freon leaked out over a couple days. Tried to replace seal but it wasn’t happening, ended up replacing compressor.
 

chillman88

Supporting Member
Supporting Member
Joined
Feb 22, 2017
Posts
6,022
Reaction score
6,152
Location
Central NY
Sounds like me. I wasn't going to "waste the money on the luxury" but the wife complained about it on vacation last year and she's managed to get me acclimated to the "finer things" so I began to wish it worked myself.

Look in the Tech articles, I ripped my compressor off to reseal it and ended up finding enough rust that I wasn't going to chance it. My AC had been open to the air for quite some time though, the valve core was missing from the high pressure side for some reason.

You might as well pull it apart and see how it looks. If it's relatively clean inside I'd reseal it and run it. I had already put new EVERYTHING else so I wasn't going to take that chance. I also know the old hoses are slightly more porous and may seep R134A where the newer hoses are made of better materials, hence why I just did everything. I really really don't want to mess with it again.
 

chillman88

Supporting Member
Supporting Member
Joined
Feb 22, 2017
Posts
6,022
Reaction score
6,152
Location
Central NY
I assume you vacuumed the system and closed the gauges and shut the pump off to make sure it holds? I just want to make sure you weren't saying it's holding vacuum and having the pump running the whole time.
 

franklin2

Full Access Member
Joined
Feb 24, 2009
Posts
5,160
Reaction score
1,384
Location
Va
R134a is cheap enough. You could fill it and see what happens. I have had compressor seals last a season and have to fill every spring, and I have had others leak quicker.

I bought a repair kit for my 1989, and just took the front apart and replaced the ceramic seal and the front gasket. It's doing fine now. If it is oily around the front of the compressor, it is more than likely the culprit of your leak. But like I said, fill it, and see what happens.

P.S. You can rent the tool to take the front of the compressor apart from one of the parts stores.
 

WAID

Full Access Member
Joined
Jul 3, 2018
Posts
134
Reaction score
154
Location
PDX
I assume you vacuumed the system and closed the gauges and shut the pump off to make sure it holds? I just want to make sure you weren't saying it's holding vacuum and having the pump running the whole time.

Valid question. Yep valves weere off(and pump). After an hour and half there was a slight movement of the needle so maybe I just got excited too soon.
 

WAID

Full Access Member
Joined
Jul 3, 2018
Posts
134
Reaction score
154
Location
PDX
Well decided that was enough of a test and decided to open it up to start replacing o-rings and check for any significant debris. No sign of black death but maybe some powdery rust or somethign on the walls of stuff. Will have to evaluate further. As I get in looking for everything that should have an o-ring, I'm wondering about a couple of connections. Does this one near the bottom of the condenser behind the grill have an o-ring? I am trying to figure out how to disconnect it and might as well make sure it has it.
You must be registered for see images attach


This seems to have a check valve or disconnect of some sort. Is it a check valve for the system? It is on it's way to the accumulator. It seems to have a flat rubber seal in one of the connections which did not come with the o-ring kit. Any idea where to get that part?
You must be registered for see images attach
 

gnathv

Full Access Member
Joined
Oct 18, 2007
Posts
1,048
Reaction score
522
Location
Athens, Al
I believe that has a screen in it to filter, clean the screen if it does.
 

chillman88

Supporting Member
Supporting Member
Joined
Feb 22, 2017
Posts
6,022
Reaction score
6,152
Location
Central NY
That first one I never disconnected. It's part of the condenser and it was on the new condenser I bought. Personally I'd chance leaving it alone.

The second one, I don't even have on my 91. Maybe @tjsea might know? (his is a bullnose) mine the hose connects directly to the condenser there, yours has a couple extra fittings mine didn't have.
 

gnathv

Full Access Member
Joined
Oct 18, 2007
Posts
1,048
Reaction score
522
Location
Athens, Al
You can use rubber stoppers to isolate your leak. You can test your evaporator, condenser, compressor and hoses.
 

Shadetreemechanic

Full Access Member
Joined
Sep 16, 2007
Posts
1,826
Reaction score
343
Location
Monteagle, TN
I would fill it with this instead of regular R-134. Its a hydrocarbon blend so the molecules are larger and more similar to r-12. That means it will not leak through the old r-12 hoses like 134 will.
Also it performs more similar to r-12. Conversions without a parallel flow condenser to dissipate the heat often don't do very well.
 

WAID

Full Access Member
Joined
Jul 3, 2018
Posts
134
Reaction score
154
Location
PDX
I believe that has a screen in it to filter, clean the screen if it does.

Opened it up and just found what looks like a quick disconnect kind of mechanism, no screen. It does have a couple of flat rubber washers that don't match anything in the o-ring kit I got.

Truck sits tonight under vacuum. I'll see how it does overnight. In the meantime I shall search for more info on the mystery part.
 

tjsea

Full Access Member
Joined
Jan 8, 2007
Posts
656
Reaction score
381
Location
Lickdale, PA
Yep, that is a quick disconnect. It was there for assembly in factory. They could have a vacuum pulled or freon in with it disconnected and then just hock it all up on the assembly line. That's why the hoses that hook to the pump had valves too. Later trucks they did away with this stuff. Those orings weren't in my reseal kit either. I ended up swapping on a newer style hose. Also the screen I think you are looking for is the orifice tube. If you separate the line going into the evaporator it is down in the evaporator inlet tube. If you are doing a 134a conversion now is the time to install a 134a orifice tube while you have it apart.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 

RDieselKid84

Full Access Member
Joined
Oct 27, 2018
Posts
99
Reaction score
45
Location
Mississippi
That is a quick disconnect that Ford used, it can be taken out if you have the right fittings but they usually don't leck. I replaced my compressor and receiver/drier and the blue orvice tube. Two years ago and I got a kit with a life time warranty. And I still use R12 it is still the best on these old A/C trucks. If you change out theR12 with 134 you will have to change the oil out and fulsh the system to get the old oil out.
 

Oledirtypearl86

Full Access Member
Joined
Sep 17, 2018
Posts
1,673
Reaction score
949
Location
Whitehall MT
AC systems are tricky because you got to rember a vacume pulls and pressure pushes i had a truck last week that the ac machine said passed a 10 min. Vacume but after a min of filling I could hear the leak
 

Forum statistics

Threads
91,217
Posts
1,128,479
Members
24,045
Latest member
Ramtough01

Members online

Top