Which side is the Low Side?
Thread Starter
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
Which side is the Low Side?
On my stock '72, which one of the fittings on the back of my ac is the low side? The fittings are the same size, I thought that they used to make these two different sizes so that you could be sure you were on the low side when charging the system. Thanks.
Racer
Joined: Jul 2008
Posts: 446
Likes: 1
From: Cary NC
They don't make different sizes 
If you've converted to 134a low side is a light blue cap (located right near the compressor). If not I don't know how you are charging your A/C and I advise against it because you are likely putting 134 into an r12 system which would not be good.
High side is closer to the passenger compartment than low side.
If you've converted to 134a low side is a light blue cap (located right near the compressor). If not I don't know how you are charging your A/C and I advise against it because you are likely putting 134 into an r12 system which would not be good.
High side is closer to the passenger compartment than low side.
Burning Brakes
Joined: Feb 2009
Posts: 780
Likes: 1
From: Shelby NC
Bigger line less pressure--smaller line is higher pressure. On a standard set of r12 gauges the high side and low side will not interchange as I remember. Are you R12 or has someone converted it to R134?
Racer
Joined: Jul 2008
Posts: 446
Likes: 1
From: Cary NC
It's easy task--the low side is the larger line. High side is the small line.
Bigger line less pressure--smaller line is higher pressure. On a standard set of r12 gauges the high side and low side will not interchange as I remember. Are you R12 or has someone converted it to R134?
Bigger line less pressure--smaller line is higher pressure. On a standard set of r12 gauges the high side and low side will not interchange as I remember. Are you R12 or has someone converted it to R134?
Melting Slicks
Joined: Mar 2008
Posts: 2,336
Likes: 1
From: North Bellmore Ny
St. Jude Donor '09
It's an easy task with 134, if you have r12 you need someont to drain the system if you want to do it legally. Also they won't sell r12 to consumers. If you have r12 go get it professionally drained and convert to r134a yourself (kits can be bought at autozone for around 50)
But you can just add R-134a with the screw on kit and it will work trust me. I have done this on 3 cars 1977 corvette, 1982 old cutlass & a 1990 ford taurus. I didn't drain system but added r134 kit to high and low side. after adding r134a all cars were blowing colder air than when they were new.
Melting Slicks
Joined: Mar 2008
Posts: 2,336
Likes: 1
From: North Bellmore Ny
St. Jude Donor '09
The low side is the cold side
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
The purge/charge system in the AIM connects to both sides of the system so that's not much help.
Hopefully someone who is knowledgeable on AC systems will chime in to add to or correct my guesstimates.
If your system is intact just do a Google search for 'automotive air conditioning' and you should be able to figure out the connections by yourself.
Rick B.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Make sure you get it figured out before you try and charge it. Most of the cans the R-12 or R-134 come packaged in don't like 300 PSI very well. Be a shame to blow the can up in your hand. They do have a blowout disc in them, but if it's pointing the wrong way, you can see how it could hurt.
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Racer
Joined: Jul 2008
Posts: 446
Likes: 1
From: Cary NC
But you can just add R-134a with the screw on kit and it will work trust me. I have done this on 3 cars 1977 corvette, 1982 old cutlass & a 1990 ford taurus. I didn't drain system but added r134 kit to high and low side. after adding r134a all cars were blowing colder air than when they were new.A. Illegal to release into the air.
B. Releasing contributes to global warming.
I'm not trying to be a tree hugger because we all know that's not what a corvette is about but if everyone will start doing this we will get a bad rep and the EPA might become more strict and not sell 134 to us just so we don't convert...
My Suggestion if you go the DIY route, which I encourage because it is rather simple:
1. Get R12 pulled by a professional (It won't cost more than 10-20)
2. Change the fittings(included in kit)
3. Change compressor oil (included in kit)
4a. Add dyed refrigerent so if there are ever leaks it is easy to track, if you don't want to go to step 4b.
4b. Add regular R134A
5. Check for leaks and make sure the system holds pressure (you will need to rent a pump at autozone... Has guages)
6. Fire her up and let her run on High and Max Cold for 15 minutes.
7. ENJOY YOUR AIR CONDITIONED VETTE
Thread Starter
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
Thanks
It's an easy task with 134, if you have r12 you need someont to drain the system if you want to do it legally. Also they won't sell r12 to consumers. If you have r12 go get it professionally drained and convert to r134a yourself (kits can be bought at autozone for around 50)
And thanks for all the other replies.
Melting Slicks
Joined: Mar 2008
Posts: 2,336
Likes: 1
From: North Bellmore Ny
St. Jude Donor '09
Sure you CAN do that but consider this first:
A. Illegal to release into the air.
B. Releasing contributes to global warming.
I'm not trying to be a tree hugger because we all know that's not what a corvette is about but if everyone will start doing this we will get a bad rep and the EPA might become more strict and not sell 134 to us just so we don't convert...
My Suggestion if you go the DIY route, which I encourage because it is rather simple:
1. Get R12 pulled by a professional (It won't cost more than 10-20)
2. Change the fittings(included in kit)
3. Change compressor oil (included in kit)
4a. Add dyed refrigerent so if there are ever leaks it is easy to track, if you don't want to go to step 4b.
4b. Add regular R134A
5. Check for leaks and make sure the system holds pressure (you will need to rent a pump at autozone... Has guages)
6. Fire her up and let her run on High and Max Cold for 15 minutes.
7. ENJOY YOUR AIR CONDITIONED VETTE
A. Illegal to release into the air.
B. Releasing contributes to global warming.
I'm not trying to be a tree hugger because we all know that's not what a corvette is about but if everyone will start doing this we will get a bad rep and the EPA might become more strict and not sell 134 to us just so we don't convert...
My Suggestion if you go the DIY route, which I encourage because it is rather simple:
1. Get R12 pulled by a professional (It won't cost more than 10-20)
2. Change the fittings(included in kit)
3. Change compressor oil (included in kit)
4a. Add dyed refrigerent so if there are ever leaks it is easy to track, if you don't want to go to step 4b.
4b. Add regular R134A
5. Check for leaks and make sure the system holds pressure (you will need to rent a pump at autozone... Has guages)
6. Fire her up and let her run on High and Max Cold for 15 minutes.
7. ENJOY YOUR AIR CONDITIONED VETTE
Racer
Joined: Jul 2008
Posts: 446
Likes: 1
From: Cary NC
So then once it's professionally drained, at the same time they can pull the vacuum and see if it holds, then I can convert it myself to 134a without changing any other parts? Except probably need to change the drier after it's drained, before pulling vacuum, all before charging. Thanks.
And thanks for all the other replies.
And thanks for all the other replies.
Racer
Joined: Jul 2008
Posts: 446
Likes: 1
From: Cary NC
I understand clearly I would never tell someone to release R-12 into the open air. What I am saying is if the system holds pressure you can just add the 134A into the system that still has R-12 in it. I have done the twice myself and also have recommended the to others without one sigle complaint.
