A/C compressor always on
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
After a terrible day on the golf course, I thought getting back to fixing my AC might cheer me up but today is just not my day.
I got the schrader tool and valves, orifice tube and was all set to vacuum it out. I was able to tighten the low side schrader valve but not the high. Then I realized (should have before) that the high side connect looks different. Is this a different type of schrader valve? See pics 1 (low) & 2 (high) and the tool I bought (pic 3). I think I saw a thread that the high side is a different kind of valve.
While I'm here, can someone confirm that the orifice tube I bought is the right one? The FSM is useless for the AC pics so I posted asking for the location of the orifice tube on another thread but if someone has that too, great.
I got the schrader tool and valves, orifice tube and was all set to vacuum it out. I was able to tighten the low side schrader valve but not the high. Then I realized (should have before) that the high side connect looks different. Is this a different type of schrader valve? See pics 1 (low) & 2 (high) and the tool I bought (pic 3). I think I saw a thread that the high side is a different kind of valve.
While I'm here, can someone confirm that the orifice tube I bought is the right one? The FSM is useless for the AC pics so I posted asking for the location of the orifice tube on another thread but if someone has that too, great.
The Schrader valve removal tool you have is really for tires. Even though the valve is a physical fit the length of the tool may not be long enough. AutoZone also sells this tool which looks like a screwdriver but the shaft has a long reach to get deep in there.
Bought some orifice tubes for my 94 which I have not used yet but should be the same part as a 96. It's a Santech MT0097.
There is also a orifice removal tool. I borrowed it from AutoZone but would not fit in due to the physical confines. I built a tool which should work but have not used it yet. You may not want to mess with the orifice tube if you don’t have to.
Last edited by pcolt94; Jul 4, 2017 at 09:18 PM.
Instructor
Joined: Sep 2004
Posts: 139
Likes: 3
From: Rockland County NY
Thanks. I just found some youtube videos about how bad these high side ac ports are. Can they be changed back to a schrader type connector?
Back to autozone I guess.
re: orifice tube. I watched a bunch of videos and they seem to show very clogged orifice tubes. So why wouldn't I want to put a new one it if I have to vacuum the system anyway?
Back to autozone I guess.
re: orifice tube. I watched a bunch of videos and they seem to show very clogged orifice tubes. So why wouldn't I want to put a new one it if I have to vacuum the system anyway?
Instructor
Joined: Feb 2016
Posts: 111
Likes: 10
Thanks. I just found some youtube videos about how bad these high side ac ports are. Can they be changed back to a schrader type connector?
Back to autozone I guess.
re: orifice tube. I watched a bunch of videos and they seem to show very clogged orifice tubes. So why wouldn't I want to put a new one it if I have to vacuum the system anyway?
Back to autozone I guess.
re: orifice tube. I watched a bunch of videos and they seem to show very clogged orifice tubes. So why wouldn't I want to put a new one it if I have to vacuum the system anyway?
Yes, I think you should change the orifice. Very simple to do, just make sure you install it correctly, it is directional. I have changed several, and they all have had "debris" on the screen.
Instructor
Joined: Sep 2004
Posts: 139
Likes: 3
From: Rockland County NY
There are a couple different valves I see online. Can someone confirm that this is the correct one on amazon - "ACDelco 15-5438 GM Original Equipment Air Conditioning Service Valve"?
BTW - these are $4 while autozone has them listed at $13. I hope these aren't the ones that fail quickly!
BTW - these are $4 while autozone has them listed at $13. I hope these aren't the ones that fail quickly!
Last edited by barry96; Jul 5, 2017 at 12:21 PM.
Instructor
Joined: Sep 2004
Posts: 139
Likes: 3
From: Rockland County NY
After finally getting the high pressure valve replaced, replacing the orifice tube and buying a vacuum pump, I finally set out to tackle recharging the system. This pump could only pull 22lbs of vacuum (unless the guage was wrong), I ran it for 2 hours and it held steady when I turned the pump off. I then began recharging. I noticed that the high pressure was not registering anything. Looks like I didn't have that connector open enough (people warned not to have it push down all the way or it might break the valve again!). But as I understand it, the with the compressor off, the vacuum on the low side will work on the whole system - correct?
Anyways, after about 12 oz of 134a, the system was working properly and as I kept filling the compressor did not pull down the low side enough to shut it off. So I emptied a little 134a and it was again cycling nicely (roughly 10 seconds on, 3 seconds off) and the temperature at the vent was 42F.
So the system is working but on only 12oz on 134a. How is this possible or what am I doing/measuring incorrectly?
Anyways, after about 12 oz of 134a, the system was working properly and as I kept filling the compressor did not pull down the low side enough to shut it off. So I emptied a little 134a and it was again cycling nicely (roughly 10 seconds on, 3 seconds off) and the temperature at the vent was 42F.
So the system is working but on only 12oz on 134a. How is this possible or what am I doing/measuring incorrectly?
