Recharging A/C system
05-06-2004, 08:39 PM
#1
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Recharging A/C system
One of the things I never did at the shop was recharging an A/C system. I guess not TOO many racecars need to have their A/C systems recharged these days
I was told by the PO that the system was converted to R134a a while back, though I have not confirmed/denied this myself. I noticed one shrader valve by the driver's side strut tower, but didn't know if that was a sign of R12 or not. I haven't looked by the compressor to find the connections down there to see if they are still shrader or not, and didn't know if all are converted over or if some are left as shrader.
I bought a leak-stop and recharge bottle all of R134a as well as the connector hose to put them in. Now all I need to find out is:
1) If my A/C system is in fact R134a - and if I need the conversion kit
2) What connector is the one I need to recharge (between the compressor and evaporator, correct?)
3) If I need to somehow open a low pressure fitting when I recharge.
Any and all help would be greatly appreciated... I feel like a dumbass asking how to do this stupid simple process... but humility is to be grasped, right?
TIA guys.
I was told by the PO that the system was converted to R134a a while back, though I have not confirmed/denied this myself. I noticed one shrader valve by the driver's side strut tower, but didn't know if that was a sign of R12 or not. I haven't looked by the compressor to find the connections down there to see if they are still shrader or not, and didn't know if all are converted over or if some are left as shrader.
I bought a leak-stop and recharge bottle all of R134a as well as the connector hose to put them in. Now all I need to find out is:
1) If my A/C system is in fact R134a - and if I need the conversion kit
2) What connector is the one I need to recharge (between the compressor and evaporator, correct?)
3) If I need to somehow open a low pressure fitting when I recharge.
Any and all help would be greatly appreciated... I feel like a dumbass asking how to do this stupid simple process... but humility is to be grasped, right?
TIA guys.
05-06-2004, 10:44 PM
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A/C recharge
Don't feel like a dumbass. I went through this same exercise last month here on the forum and got a lot of help, so I'm obligated to pass the information along to the next guy.
#1. How do you tell if there is 134a or the old R12 in the system? Well, you either have to trust the P.O. or purge the entire system and start over. The Schrader fitting up at the fender is the high pressure fitting. The original factory fitting was also a Schrader so that probably won't help you much. Some of the aftermarket retrofit kits have nice blue and red caps that you place over the factory Schraders to signify that the car has been converted, but that's a pretty unreliable method. Assuming that it really is 134a, then you can move onto step #2.
#2 & #3: Warning -- wear safety glasses. You'll understand by reading further.
Injecting the stop-leak and refrigerant: You'll want to use the connection closest to the compressor. On my car, the low pressure schrader fitting was actually on the compressor itself, so that made it easy. Just in case your system pressure is too low and your compressor doesn't turn on right now, you'll have to jump the low pressure switch. It's located on the side of the receiver/dryer just behind the driver's headlight.
Inject the stop-leak first. Hopefully it has a little Ester oil or some sort of oil mixed in to help lube the compressor. Hook up your line between the stop leak can and the low side fitting, then start up the car and turn on the A/C. Get back under the car and open the valve from the can. Hold the can upside down and shake it until it feels empty and you don't hear any hissing. Then disconnect the line at the fitting.
Keep the car running with the A/C on, attach the refrigerant can and hook it up to the low side fitting. Open the valve and again, hold the can upside down and let it empty into the system. Disconnect the line from the low pressure fitting when you're done.
Finally, with the A/C still running, go topside and look at the sight glass on the top of the receiver/dryer unit. If you see a clear river of liquid refrigerant running under the glass you are in good shape. If you see bubbles it either means you still don't have the system fully charged or you have air trapped in the system.
BTW, since the car is running during this whole process, every time you disconnect the hose from the low pressure fitting a little bit of fluid is going to spray back at you. That's why I mentioned safety glasses. Apparently liquid refrigerant is nasty stuff if it gets in your eyes.
Good luck!!
Greg W.
#1. How do you tell if there is 134a or the old R12 in the system? Well, you either have to trust the P.O. or purge the entire system and start over. The Schrader fitting up at the fender is the high pressure fitting. The original factory fitting was also a Schrader so that probably won't help you much. Some of the aftermarket retrofit kits have nice blue and red caps that you place over the factory Schraders to signify that the car has been converted, but that's a pretty unreliable method. Assuming that it really is 134a, then you can move onto step #2.
#2 & #3: Warning -- wear safety glasses. You'll understand by reading further.
Injecting the stop-leak and refrigerant: You'll want to use the connection closest to the compressor. On my car, the low pressure schrader fitting was actually on the compressor itself, so that made it easy. Just in case your system pressure is too low and your compressor doesn't turn on right now, you'll have to jump the low pressure switch. It's located on the side of the receiver/dryer just behind the driver's headlight.
Inject the stop-leak first. Hopefully it has a little Ester oil or some sort of oil mixed in to help lube the compressor. Hook up your line between the stop leak can and the low side fitting, then start up the car and turn on the A/C. Get back under the car and open the valve from the can. Hold the can upside down and shake it until it feels empty and you don't hear any hissing. Then disconnect the line at the fitting.
Keep the car running with the A/C on, attach the refrigerant can and hook it up to the low side fitting. Open the valve and again, hold the can upside down and let it empty into the system. Disconnect the line from the low pressure fitting when you're done.
Finally, with the A/C still running, go topside and look at the sight glass on the top of the receiver/dryer unit. If you see a clear river of liquid refrigerant running under the glass you are in good shape. If you see bubbles it either means you still don't have the system fully charged or you have air trapped in the system.
BTW, since the car is running during this whole process, every time you disconnect the hose from the low pressure fitting a little bit of fluid is going to spray back at you. That's why I mentioned safety glasses. Apparently liquid refrigerant is nasty stuff if it gets in your eyes.
Good luck!!
Greg W.
05-06-2004, 11:43 PM
#3
Hey Man
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Not knowing what your system is filled with is not good. I would purge and vac the system well before converting as well as replacing the drier. If the wrong (R-12) oils are left in there you will get a black gunk that will eventually ruin the compressor. If you are sure your car has been converted to R-134a , waiting for the sight glass bubble to clear can often result in way too much refrigerant being installed. With the higher pressures and smaller molecular size of R-134a this is not good for the system to be overfilled. A manifold set is the best way to do this if you are unsure. I would go to shop the first time then do the recharges yourself after that.
05-07-2004, 12:53 AM
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Hmmm... well I might just wait until next week then until I'm back at the shop. I'm the impatient type, but it can wait until I have the full gauge and vac system tools at the shop at my disposal.
05-07-2004, 02:11 PM
#6
Three Wheelin'
Todd:
The low pressure fitting is at the compressor for the '87 and later cars.
Kevin:
Having the right tools can mean the difference between success and failure. If the retrofit was properly done, the only hoses that will attach are the R-134a specific ones. During the retrofit you are supposed to install new schraders and adaptors that allow the snap loc style manifold hoses to be installed. All part of the effort to minimize "venting" of the refrigerant.
Some models of the 968 had R-134a, and IIFC the specificed amount of refrigerant was 30oz. I am not sure if the systems are identical or not, but I have been told to start with 80% of the R-12 spec. and add from there until the right pressures are reached.
I have been trying to get mine to evacuate below 27" and it will not go. Guess I have a leak somewhere. I am at roughly 500' above sea level, so I need 29" or so to dry the system out. I am learning about A/C systems as I go.
The low pressure fitting is at the compressor for the '87 and later cars.
Kevin:
Having the right tools can mean the difference between success and failure. If the retrofit was properly done, the only hoses that will attach are the R-134a specific ones. During the retrofit you are supposed to install new schraders and adaptors that allow the snap loc style manifold hoses to be installed. All part of the effort to minimize "venting" of the refrigerant.
Some models of the 968 had R-134a, and IIFC the specificed amount of refrigerant was 30oz. I am not sure if the systems are identical or not, but I have been told to start with 80% of the R-12 spec. and add from there until the right pressures are reached.
I have been trying to get mine to evacuate below 27" and it will not go. Guess I have a leak somewhere. I am at roughly 500' above sea level, so I need 29" or so to dry the system out. I am learning about A/C systems as I go.
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05-07-2004, 05:16 PM
#9
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yeah... not i'm confused too... simply put, is the high pressure side by the driver's side strut tower or by the compressor... and which is to be filled??
lol, i'm so lost
lol, i'm so lost
05-07-2004, 05:20 PM
#10
Three Wheelin'
Fill at the compressor, which is the low (suction) side. Manifold sets connect to both high and low sides. The high side is by the strut mount near the brake booster, tubo water pump etc. It is physically higher too.
