Hi,
I had to replace my A/C condensor and will need to fill it back up with R134a. I was just wondering if anyone knew how many ounces of refrigerant the C5 takes? Is there a site that maybe lists all GM cars?
Thanks!
John

 

I found the manual and it said to use 1.75 lbs which should be equivalent to 28 ounces.

 

Please dont get mad but,, I have to ask, Did you replace the receiver/dryer when you had the system apart and did you vacuum the system out prior to filling it?

Thanks

Bill

 

In no way will i get mad at any questions or comments. I admit to knowing more about engines than A/C systems. In fact I look at A/C systems just as a necessary evil (as in you kinda have to have it but they are so much of a pain to mess with)

But to answer the question, heres what happened so far: The car was dinked in the front and the condensor got bent up a little. The system was not punctured or anything but the condensor still had to be replaced. So I disconnected the condensor, all the R134a fizzed out of the system where I disconnected it (down at the large connector at the bottom of the condensor), then I carefully taped up and sealed these connections so that no debris or water would get into the system. The car sat for about 9 months in my garage while I worked on it. I got another condensor and connected it back up. Then I took it to a shop to have the system vacuumed and refilled with r134a. The guy said something to the effect that the car didnt really want to accept the r134a but finally got some in there. I then started the car, turned on the A/C and the air didnt really get cold. And he said that when I did this, the low side gauge on his equipment PEGGED out to the max of 350 psi. Normally the low side should read around 30-40 psi from past experience with A/C systems.

If anyone has any suggestions they are welcome as you guys probably know more than I do about this stuff

 

Bill, please explain where you're going with this. I've been trying to learn about a/c systems on several websites and even a forum, but I'm still pretty clueless when it comes to a/c repair. Why would the receiver/dryer have to be replaced? Can it be reconditioned or cleaned at all? Doesn't releasing the pressure do the same thing as vacuuming the system? I thought vacuuming would be a waste of time since a tiny amount of oil and the proper coolant pressure was all that mattered.

Eugene

 

WOW I have my work cut out for me!!! To start off I am not a licsensed AC guy but have fix and rebuilt many friends and all of my AC systems with EXCELLENT success!
When you open any freon system the system becomes contaminated with moisture and air(non condenceables) The air is removed and miosture is removed by placing the "SEALED" system under a VACUUM for a specific ammount of time. The receiver/dryer contains a desicant bag that filters and removes any moisture that may be left in the system.
Moisture is a VERY BAD thing in an AC system as it causes the moisture to turn into an acid and it destroies the aluminum components.

For your suction side to read high you orfice tube has to be clogged. The high pressure side should have also read low!
You need to get a more knowledgable AC tech because he SURE has things hosed up!

If the freon fised out you more than likley lost some or most of your OIL charge! Oil needs to be added! How much? Got me? How much came out??
Get your car to a certified AC mechanic who knows his stuff.

Bill

 

I went and got a brand new GM dryer because I was told they go bad if the system is left without freon. My system had no freon in it for at least a couple of months.

If that does not fix the issue I will have to check my orfice tube. I was told it is directly behind the motor on the upper side of the firewall. HOW IN THE WORLD DO YOU GET TO THAT DARN THING?

The fender sticker says that the A/C system takes 1.75 lbs (28 oz) of freon. After a complete vacuum, do I add 28 oz of freon and then oil on top of that? Or should the total freon/oil mixture be 28 oz? Is all the oil removed after a vacuum has been performed? Uggh! I hate A/C systems!

John

 

If i were you I would change the dryer,,, anytime the system is open,, time for a new dryer,,, moisture in the system creates acid and will creat havok. The dryer should cost less than $50

In addition, when you have a freon leak, you almost always lose some oil as well. I am not certain but I believe GM uses "PAG" type oil, maybe 100 viscosity. You can pick this up at autozone in an 6oz can I believe. Regardless, to be safe I would add about 50% of the system requirements. (DO NOT USE ANY OIL OTHER THAN THE FACTORY TYPE UNLESS THE ENTIRE SYSTEM HAS BEEN CHANGED/FLUSHED) PAG< ESTER etc are not comp. and will create a mess. You have no idea how much oil remains in the system, but 50%, this is a good compromise. You are better to have a little too much that too little, Many times people burn up a compressor b/c they recharge a system and forget about the oil necessary to lubricate.

Secondly, as the gentleman stated above,,, you must pull a deep vacuum on the system, this "boils" all condensation out of your system, now you are ready for a charge.

YOU CAN NOT charge a system that has been opened unless it is under a vacuum. If you do you will have air and freon mix which will not cool, thats probably why you arent getting squat for cooling now. The real way to charge is to use the manual as a guide, but to finalize the charge via pressure. YOU ALWAYS charge into the low side port,,, and very slowly at that. Invest in a $100 set of guages.

To make sure you have just the right and most efficient cooling, slowly add R134A until your highside pressures are 2.2 X's the ambient air temperature. So if its 85 degrees out your high side pressure should be about 180-185 with the compressor on, A/C on max

After some so called mechanic supposedly fixed my A/C i learned the right way and did it myself... Aircondition.com is also an excellent resource.

 

And no John, oil is not removed by the Vacuum. Only by a leak, rapid discharge of the system, or removal of components

 

Great information here, thanks guys! The only thing I'm still uncertain about is the oil. On many of the R134 kits I've seen, they include oil in the mixture. Does this oil get added to the total amount of oil required for the system, or does the oil required for the system get added seperately?

I have to backup the recommendation for getting good gauges. I tried the parts store kits with built-in guages and attachments, and it leaked like crazy.



Eugene

 

The safe bet would be to add an oil charge! The receiver / drier will store some extra oil if there is a small amount too much. MAKE SURE that it is for R134A. Add the oil charge and then the freon.

Do NOT over charge the system!! If you do you will destroy the compressor! It is best to be a little low than too full!

BC

 

Bill,
When you say add the oil before the r134, how many ounces should I add? An '02 says its supposed to have 28 oz of coolant. Im not certain but I think they sell the oil in its own 6 oz small can? Should I add one of these small oil cans and then top it off with r134a until the high side reaches 2.2 times the ambient temperature? I do already own a set of nice A/C r134 gauges so I'll just use those.

This thread has really helped me out, thanks

 

Thats what I would add! 3-6 oz of oil, and then freon! I think that the suction/low side should read around 25-30 psi at a high idle when it is fully charged. I charge mine up until the low pressure switch just stops cutting out and then I add a couple more PSI of freon. You can always add more if it is a bit low. Auto zone sells some temperature indicating bands that you can wrap on the inlet and out let of the evaporator! When the temperature of the inlet is equal/same as the outlet side of the evap, it is suppose to be at optimum charge!