AC--which is the "low side"?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,023
Likes: 2
From: TEXASTEXASTEXASTEXAS TEXASTEXASTEXASTEXAS
St. Jude Contributor
AC--which is the "low side"?
How do I identify the low pressure port on my '78's AC? I want to add some seal conditioner and maybe some R-12 (I've got a few cans left over from years ago when I charged the AC on my trucks).
JB
'78SA
JB
'78SA
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: AC--which is the "low side"? (JB)
The low pressure is also called Suction & comes from the pass. compartment to the Compressor & the High pressure goes from the Compressor to in front of the radiator.
Racer
Joined: Aug 2001
Posts: 457
Likes: 0
Re: AC--which is the "low side"? (JB)
The suction , low side, will be the largest of the tubes. Follow it until you find the access port.
Before putting the freon in, make sure you purge the hose you are going to use with the freon can, to blow any air out of it so no air goes into the a/c system - this is very important .
RR
Before putting the freon in, make sure you purge the hose you are going to use with the freon can, to blow any air out of it so no air goes into the a/c system - this is very important .
RR
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,023
Likes: 2
From: TEXASTEXASTEXASTEXAS TEXASTEXASTEXASTEXAS
St. Jude Contributor
Re: AC--which is the "low side"? (Rumpity Rump)
Okay, just looked at the system--there seem to be two ports, one on what must the the high pressure side from your descriptions on the line near the side of the engine compartment. The other port fitting seems to be right on the block on the back of the compressor where the other line connects to the compressor. Does this sound right?
JB
JB
Racer
Joined: Aug 2001
Posts: 457
Likes: 0
Re: AC--which is the "low side"? (JB)
JB,
The port at back of the compressor sounds like the suction port, because the other one is on a small line which would be either the hot gas or liquid line port. Also, you can check on the largest line near the firewall...often times they put an access port in that vicinity as well. If you still have some freon in the system, y ou could start the car and run the a/c , then feel the lines. The biggest line should feel noticably cooler than the other small ones.
Before charging the system, dont forget to power wash the condensor coil by the radiator , back and front. This helps tremedously in surrendering the heat to the air when its clean and boosts the capacity of the a/c system overall.
Good luck. Wear goggles.
How are you going to know when you have put enough freon in ??? Do you have a sight glass in the liquid line..if so, slowly charge the system until no more bubbles appear in the sight glass. Blower should be on the highest speed in the cabin, and 'max cool' position. Engine should be at a fast idle .
Dave
The port at back of the compressor sounds like the suction port, because the other one is on a small line which would be either the hot gas or liquid line port. Also, you can check on the largest line near the firewall...often times they put an access port in that vicinity as well. If you still have some freon in the system, y ou could start the car and run the a/c , then feel the lines. The biggest line should feel noticably cooler than the other small ones.
Before charging the system, dont forget to power wash the condensor coil by the radiator , back and front. This helps tremedously in surrendering the heat to the air when its clean and boosts the capacity of the a/c system overall.
Good luck. Wear goggles.
How are you going to know when you have put enough freon in ??? Do you have a sight glass in the liquid line..if so, slowly charge the system until no more bubbles appear in the sight glass. Blower should be on the highest speed in the cabin, and 'max cool' position. Engine should be at a fast idle .
Dave
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,023
Likes: 2
From: TEXASTEXASTEXASTEXAS TEXASTEXASTEXASTEXAS
St. Jude Contributor
Re: AC--which is the "low side"? (Rumpity Rump)
No, no sight glass. My original plan was to use this gadget I used several years ago when I charged the AC in my trucks--it's a piece of plastic that you stick to the low side line and it changes color when you've got the right amount in, I suppose because the line would be at the right temp. However, I can't find the little son of a gun, and I guess I'll have to see if I can borrow some gauges from someone.
Thanks,
JB
Thanks,
JB
Racer
Joined: Aug 2001
Posts: 457
Likes: 0
Re: AC--which is the "low side"? (JB)
JB,
Just be careful not to overcharge it otherwise the compressor wont last as long. If the s ystem is bone dry , then id put a Sight Glass in the liquid line close to the firewall, pull a deep vaccuum to get all the air and moisture out of the system, then recharge until there are no bubbles in the sight glass at all. Thats the way the systems used to come from the factory, until , the Manufacturers changed that so the Dealerships wouldnt loose out on potential a/c recharges.(m guess anyway).
Keep kew-wull !
Dave.
Just be careful not to overcharge it otherwise the compressor wont last as long. If the s ystem is bone dry , then id put a Sight Glass in the liquid line close to the firewall, pull a deep vaccuum to get all the air and moisture out of the system, then recharge until there are no bubbles in the sight glass at all. Thats the way the systems used to come from the factory, until , the Manufacturers changed that so the Dealerships wouldnt loose out on potential a/c recharges.(m guess anyway).
Keep kew-wull !
Dave.
