Alright cool well I think that I can handle this repair.
When I was messing with the leaky line, I heard something hissing out of it. So there is still something inside of the system.
Should I evacuate the system PRIOR to working on it, just to make sure that it isn't under pressure? HVAC is nasty stuff when it goes wrong, I don't want to freeze my eyeballs off.
HVAC gurus: Are you familiar with a guide or walk-thru on the internet or on the forum somewhere that outlines the procedure for evacuating and charging the system?
Also, how much and what type of PAG oil needs to go in the system? I have read 2-2.5 cans of R134 are needed, but what about oil?
Thanks!
No step-by-step although advanced/autozone sell one of the typical haynes books on A/C repair.
Here's the procedure:
1. discharge the system so that a gauge reads 0 PSIG.
2. remove old hose. I would probably remove the end that is "highest" first (the end by the drier) and then hold the hose up vertically to allow any compressor oil that is in it to drain down toward the compressor so that you don't remove any by accident.
3. use a drop or two of what is left in the hose to lube the new hose o-rings, or you can spend 5 bucks and buy a can of PAG-type oil (weight doesn't matter, you are not going to pour any in to the system, just lube the o-rings so they don't get pinched/nicked/etc during installation.
4. Connect the new hose making sure you hear a "click" when the spring snaps closed.
5. Connect a vacuum pump thru a set of manifold gauges and pull a 250 micron vacuum (if you don't have digital gauges that read in microns, pull at least a 29" vacuum and let the pump run for 30 minutes after getting to that level. If you can't get to 29" either the pump is no good or you have a leak.
6. After 30 minutes at 29" or better, close the manifold gauge valves and turn off the pump. The vacuum should hold for at least 5 minutes with no appreciable drop. If you have a digital gauge set, it should stay below 1000 microns or so. If it rises to about 1500 and stops, you still have moisture in the system. Turn the pump on, open the valves again, and go for another 30 minutes.
7. When you can hold a strong vacuum for several minutes with the pump off and valves closed, you are ready to charge. This is the easy part. Under your hood, there is a sticker that tells you the proper charge. Best way to charge is to get enough cans to that you have more than enough R134a to charge. 3 cans is a slight overcharge although without my book handy I don't remember the exact charge weight. Take the first can, connect to the manifold, but before charging, let the hose attached to the can leak for a couple of seconds at the manifold to get the air out of the hose. Now turn the can upside down and charge into the low-pressure side. You won't get the whole can in, probably, before the pressure becomes too high. You can heat the can using hot water, or you can crank the car and finish charging.
8. If you are going to crank the car, give the system a few minutes first, so that there is no liquid in a bad place. Now there are two options, depending on how your A/C is piped. If the suction line valve is before the drier (the connection would go valve, drier, compressor) then you can safely charge using liquid. If the valve is after the drier (so that you see drier, valve, compressor) then you need to charge gas only. So, either turn the can upside down if a liquid charge is OK, or right-side up if not, and crank the car. Put the A/C on max, fan on high, and open the low-pressure manifold valve and start charging.
9. If the compressor doesn't run very much, unhook the low-pressure cycling switch and short the connector using a small piece of wire so the compressor will run continuously to speed the process up. If it runs all the time, this is not necessary.
10. For the final can you need to be more accurate for the optimal charge. If you want, you can "guess" and probably end up OK. Say the sticker says "32 oz charge". 2 cans is 24 oz, 3 cans is 36 oz. Using all 3 cans will result in a 4 oz overecharge. Probably won't hurt, but it can be avoided. Use a postal scale for the last can, and just add what is needed. Once the weight of the can drops by 8oz, shut it off and you are done. Or you can make a fairly good guess by leaving about 1/3 of a can which will be pretty close.
If you have a good temp gauge, turn the A/C on max, fan on high, and cool the interior to a cool level. Then turn the fan on low and measure the air temp discharging from the center vent. It should be around 40 degrees, perhaps cooler. If it is down around 32 it will tend to freeze up more and your cycling switch might need replacing. 36-38 will cool the interior just fine, even on normal A/C setting (not max-recirc) when the outside temp is past 100...
Hope that helps. And remember one extra point. If you seem to have a leak, that the leak can just as easily be in the manifold gauge hoses and stuff as it can be in the actual A/C system, so you might have to check. You can always charge just enough gas to get the pressure up to 60-70 psi and use soapy water to find a leak in the manifold gauge set.
Missed your other questin. To replace the hose, you don't need to add any PAG oil. If you replace the drier, you need to drain it and measure how much oil is inside, and add that much to the new drier. The condenser might hold an ounce or two, and you'd need to add that much in if you replace the thing.
