TL:DR Pulled vacuum on A/C system after replacing condenser/drier and it leaked slowly over the course of a week. Then, I tried adding refrigerant, but system stopped pulling in refrigerant even though I pulled a vacuum on the system and the compressor was on.
The A/C in my 2006 Pontiac Vibe wasn't cooling as well as it once did. I noticed that if I had recirculate on it would eventually cool the air down enough on hot days but if I pulled in fresh air from outside the temperature wouldn't be that much cooler. I suspected this was do to my condenser being pretty old and having a considerable amount of the fins missing. I verified this as the pressure seemed fine and it didn't need any more refrigerant. I felt pretty good about this as this meant I didn't have a leak. I set out to replace the condenser and Receiver Drier / Accumulator. I ordered the part from RockAuto (https://www.rockauto.com/en/moreinfo.ph ... 08&jsn=867), replacement O-Rings, and some PAG 46 Oil.
The actual replacement went less smoothly. First, I had the refrigerant evacuated and then set out to replace the condenser. I ended up having to drill out the the high side connection bolt as it snapped off when attempting to remove it. When I pulled the old condenser out, my suspicions were confirmed as the many of the fins that were left literally disintegrated upon touching them. I installed the new condenser, oiled the new O-Rings with PAG 46 oil, and moved the refrigerant sensor over to the condenser as well. After everything was installed, I went to pull a vacuum on the system. I rented a set of A/C manifold gauges and a vacuum pump from AutoZone for this, I am not sure what the quality of these parts are considering the vacuum pump was seemingly out of oil when I got it. Anyways, I started pulling a vacuum on the system and was able to get it down to roughly somewhere between 27-29 inHg. I then let the systems sit for about an hour and came back to check if it held vacuum. It seemed that it didn't really lose any vacuum in an hour, but I wanted to make sure there wasn't a leak. I let the system sit in vacuum over the next week and periodically checked it throughout the week. Here is a link to pictures of the readings throughout the week. These two pictures were taken in the middle of last week two days apart (https://imgur.com/a/fOdE23E) and it goes down slightly between those two days. Overall it started pretty close to 29 inHg and ended up being at roughly 20 inHg by the end of the week. This makes me think I have a leak somewhere.
This past weekend, I wasn't really sure how to track down a small leak while the system was in vacuum, so I decided to go ahead and charge the system as well as add some dye. I pulled another vacuum for about an hour. Based on the service manual (download/file.php?id=3732), I need to add roughly 4 fl oz of PAG oil because I replaced the condenser and receiver dryer. Now, most videos I saw online say to add the oil in the yellow line (feeding into the manifold gauges) that you connect the refrigerant cans to. I attempted to do this, but 4 fl oz is a lot of oil to add into that line, so much so that I would need to add oil, charge the system a little bit, disconnect the refrigerant can, add more oil, and repeat this process quite a bit. I added what oil I could, and started charging the system. This is where things get odd. The refrigerant started going in as it should and then started to slow down. I started the car up, turned the A/C on and the compressor didn't kick on. As the system continued to charge, the compressor and fan kicked on. The high pressure side started building pressure and more refrigerant was drawn in. Then it sort of just stopped taking more refrigerant and the high pressure side stopped building more pressure. I had a scale on the refrigerant can and sure enough the weight of the can was not going down. The compressor was still running. I was hoping by charging the system I would be able to track down where the leak would be by adding some dye in the yellow line as well, but I never got that far. I am well short of the amount of refrigerant I need to add to the system and the pressure on the high side aren't anywhere close to what they should be. When it stopped pulling in refrigerant, the low side was about 50 PSI and the high side was around 75 PSI. This has left me even more confused because if I had a leak I would think refrigerant should go in no problem since it would be leaking out as well. I am really not sure where to go next.
The way I see it, the system really would only be leaking in places that I have touched which include:
1. The condenser itself
2. The receiver/drier itself
3. The connection between the condenser and drier
4. The high and low pressure connections to the condenser
5. The refrigerant sensor on the condenser
6. High/Low pressure schrader valves
My follow up questions are:
1. What should my next steps be?
2. Is it possible I didn't pull a deep enough vacuum (either because the pump I rented stinks or because I have a big enough leak) and that is why refrigerant is no longer being pulled in?
3. How is it possible that I have a leak, but yet refrigerant wasn't getting pulled in? These two ideas contradict each other.
4. What is the best way to get 4 fl oz of PAG oil into my system?