AC Recharge Question

My 2008 DCSB AC system is cold but not ice cold and in the summer it takes a good amount of time to really cool down the car (10/15 mins before it starts really blowing cold air. Is that normal?). I think that over the past 18 years some coolant has leaked out of the system past the seals. Not enough to be considered a leak but enough to where it's not as cold as maybe it once was. That being said, I would like to recharge it before summer is upon us (I live in MA). I've done some research and I plan to rent all the necessary tools from autozone to do it correctly (vacuum/gauges/etc). The only question I have, and cannot find the answer to anywhere online, is if I will need to add oil when I add the new refrigerant. If/when I pull the refrigerant out of the system will oil come with it? Or does it stay contained within the system? I don't want to pull refrigerant/oil and add new refrigerant only to burn out the compressor afterwards. Any help/advice would be appreciated. Thanks!

 

oil will stay in....how are you going to pull freon out?

 

I know I should take it somewhere to have it captured but also might go the backyard approach. Any advice?

 

Have it done correctly or don’t do it at all. Most shops it should be a couple benjamins to evacuate and see if holds a vacuum and recharge.

 

Ya dealing with a flat system as a diy is one thing but when you have some charge in the system already and you're not familiar and have experience already working with A/C, it's better to go to shop. You could make things worse by introducing air into the system if the gauges are not purged or overcharging the system. Especially if you use something like "12a" which has different operating pressures and requires a very different and reduced charge to do the same job as R134A.

That said if you decided to try it anyways, when I deal with a system that isn't completely flat but lost some refrigerant over time I usually add an ounce of oil. I like oil that already has dye in it to allow for easier leak finding down the road. This can be done by pouring the oil into the yellow charge hose (remove the schrader valve if there is one in it) then purging your line. If you had a hose explode or other major and suddenly leak then I would maybe add 2-3 oz.

Since you're wanting to add to a running system, what I usually do is invert your can and with the A/C on full blast, recirc on, slowly crack the low side valve on the manifold and allow a little to flow in then close it and allow the system to operate for a few minutes for it stabilize. Preferable run the engine around 1200-1500rpm to allow the compressor to work in it's more normal operation range. Don't just bust open the low side valve as you could feed liquid into the compressor which will damage it. Check your vent temps. Don't let the temp get lower than 4-7*C or 40-45*F or the evaporator will start freezing up which will cause you more problems from over charging it.

I don't really want to give you pressures because it's very dependant on ambient air temp, humidity, vehicle condition, etc. but lets say your low side should be between 20-45 psi and high side anywhere between 120-290 psi.

When you have it charged enough then you close the high side service valve and remove from the service port, open the high side tap at the manifold, then slowly the low side at the manifold then when the low side is as low as it goes, close the low side service valve and remove it from the vehicle. This will "recover" your gauges back into the system so you don't leave like 0.5 Lbs in the gauges. Not compulsory but a good practise