Ok -- the a/c system was working great on my 1980. It was converted to 134a before I bought it in 2000. It ran so cold that it would occasionally freeze up the core in the car and I would have to turn it off to let it thaw out.

About 3 years ago I noticed that some oil came out the front seal, slung onto the backside of the hood, and then eventually ruined the paint on the other side. However, the a/c system still ran cold and had no problems.

A little over 1 year ago the aluminum line coming out of the back of the compressor developed a pin-hole leak at one of the bends and all the magic inside escaped and it doesn't cool any more.

Since I am selling the car I figured it will do better if I fix the a/c. So I bought a new manifold / line set, a new drier and new orifice tube.

Once I replace these parts what will I have to do to get it up and running again? I know I need to evac / vacuum the system down. Will I need to add new or more oil to the system? How much 134a should I put in the system? What should the low and high pressure readings be?

Any other advice?

 

Add some oil and put in about 3/4 of the freon called for on the label.

 

Ya might should replace that leaking seal while your at it

 

well, I think to do that I have to replace the compressor. Since I am selling the car, I don't plan on dumping a lot into getting the a/c working. I am going to loose thousands on the sell as it is (just the nature of custom cars).

 

anyone know of pressure settings? How about just using the 134a that comes with a little bit of oil in each can?

 

Wish I still lived in the area, I would come help you. Still appreciate the alternator fan.

I would use 1 can of refrigerant with oil and start with 2 cans of regular R134. You replace the parts, then pull a good vacuum. R134 is not at all tolerant of air in the system so it is important to get a good vacuum. Your low side gauge has an inner scale that will tell the temperature of the refrigerant. You want to try to get it where it does not cycle much and probably around 45 degrees on the gauge at high idle will be as good as you can do. If you can get lower, that is good. The high side will likely be 200-250 psi. The less air in there the better the high side will do. I usually sit the can in a pan of hot water to make it go in faster. Good luck with it.

 

Over- or under-pressure isn't good for A/C systems...

 

you can change the seal without even removing the compressor. I think Batman just did some of this

 

Come on up!! Chattanooga isn't that far away. I am exit 81 - don't even have to come near Nashville.

I will have free beer.....


Of all the work on a car, I hate a/c and painting. I just wish they would take care of themselves.

 

I just yanked the clutch/pulley assembly, only to find out that they changed the R4 machining between the old V-belt pumps and the newer serpentine belts.

 

So you couldn't swap the pullys?

 

Nope. The snout is machined differently - same casting, different prep work. Now I need to find someone with an R12 recovery system to make a house call.

 

Fun

 

If you replace the dryer you will need to dump 2 oz of oil in the dryer(heavy weight 150 vis for GM service, white and red can).

With the car idleing at around 800 rpms, the suction should be in the 28 to 32 lb range when charging r134a. The fan needs to be ran on high and the AC set to max, the windows need to be up. Once you reach this suction pressure and it is stable raise the idle up to 1500 to 1800 rpms and see were the suction pressure settles out at. The clutch should not cycle until the cabin cools enough to force the evap coil temp to drop enough to force the suction pressure to drop below the low setting on the pressure switch and disengage the clutch.

Someone posted the pressure/temp chart for r12 and r134a the other day, some good info to remember.

Also something we tend to overlook is that 134a operates at a lower pressure on the suction side to reach coil temps in the 30 deg range. The low setting on the pressure switch is set for r12 on our cars and the switch for 134a is set at a lower setting I think. I think I remember reading about this somewhere but I don't remember where. The r12 switch will work it just takes some attention to setting the suction pressure were it needs to be.

The end result should be the lowest suction pressure you can get and still get cool refrigerant back to the comp to help keep it cool. When the system is charged right the suction line to the comp will be sweting up to the comp. You don't want to put any more refrigerant in the system than you need to reach these conditions.

I don't get concerned with the high side until it reaches 275 psi. than I start looking for problems.

All these conditions count on the AC system being in top shape.

Neal

 

I hope all goes well. Last time this worked it was cold enough to keep me chilled in Arizona 110+ heat. The vent temps were only in the 60's, but when you start with 110 outside temp, 60 feels damn good. When it was in the 90's the a/c would freeze up if it was humid out.

 

No, but a question….. Mine just went out (clutch smoked while charging it).
Did you learn enough to help a Murfreesboro brother out?

 

If the clutch smoked while chartging you mat have been putting in liquid and it locked the head, or you may have over charged it, would have done the same thing.

 

All you need to do that is a set of gauges, and a empty 30 lbs canister from say R22 from some a/c guy....hook up normally , fire it off, watch both gauges, open the high side into the empty canister....watch the lo side, when the needle goes negative, close all valves and kill the compressor quickly....unplug it....

I even did this to my house hold system some years ago,,....had two valves and cut off switches on hi and lo sides....so when lo side went vacuum, the system thought it was outta freon, and shut the compressor down....simple as hell.....I cut the lines, moved the air handler, got my wife's son out to fix the lines....suck down the system, and then opened the valves to the outdoor unit....

never lost a drop....this is pushing 5 years ago now, in FLORIDA....