2009 Pontiac G3 AC Probs (DIY diagnosed and repaired! With pics)

[The_Limey]

So, I'm still not having a whole lot of luck. It seems there were some crossed wires when I spoke to my father-in-law's friend last night. As soon as he realised what I aimed to use his compressor for, he began backpedalling and really didn't seem to want to get involved with AC systems for fear he might break something.

He recommended a friend of his who has been fixing AC systems since year dot, and said he'd give him a call to warn him I'd be in contact. After a brief phone call this morning I was no better off. He quoted $80 all in, so I figured I'd just spend an extra $20 and take a trip to Harbour Freight. So now I had this to play with:




I ran it for an hour and managed to pull just about 26inHg, which I guess will have to do. It certainly seemed to be boiling off a lot of moisture.



And then for the moment of truth. I closed the manifold gauges, turned the pump off, and watched the gauge nosedive. In less than a minute it was back up to atmospheric pressure.



I've a seriously leak somewhere. I'm pretty sure it's from the compressor interface. I'm almost certain I could hear the air rushing in there, and it doesn't look like the pipes are sat flush with the ports. My main concern is, given I left the car outside in the driving rain last night, whether I need to start all over again or at least replace the dryer?

Is PAG oil contamination a worry given how hygrophobic it is?

How quickly do these dryers saturate?

I have a spare dryer, but I'm guessing changing it involves pulling the radiator off again. I'm gonna go leak hunting in the meantime...

[xintersecty]

if the system is relatively sealed then it's not drawing that much air. So you don't have to replace the dryer. I mean seriously you have to take it out of the packaging and instal it. Love your vacuum pump and gauge.

The other thing you can do is pressure test it. Apply pressure to parts that you think are leaking to find the leak, then do the draw down. That if you have access to dry air or nitrogen.

[The_Limey]

No dry air or nitrogen, unfortunately. I'm reasonably confident I know the source of the leak, so I'll replace the o-rings at the compressor ports and make extra-specially sure the pipes are seated this time. I thought it was odd when I was having a hard time threading the nut onto the stud the other night. Even once I did, I got barely a few turns before it felt tight. I should've investigated further. Anyway, I guess I'll leave the dryer and PAG oil as they stand.

UPDATE!

I gave in and bought myself a can of R134a with UV dye, and a black light. After starting the car with the AC on and the fan set low, I topped the system up just enough to prompt the compressor into action before shutting everything back down again. Almost immediately, this leak made itself known at the low pressure line junction by the airbox:



After swapping the o-ring out and retesting it, the leak was still present. Turns out a discrepancy in o-ring spec was to blame (green = generic crap, black = OE):



Swapping back to the old o-ring soon sorted that one out. After more vacuuming, the gauges were still returning to ambient pressure as soon as the pump was off, albeit a lot slower. This time, I tracked down a barely audible hiss of air entering the condenser at the high pressure line in (on the dryer side).



No sign of a leak, but I can definitely hear it. I'm going to head to the local GM dealer in the morning and see if I can get a proper AC Delco o-ring and be done with it.

[The_Limey]

I went down to the garage this morning to check the VIN while I was on the phone to the parts guy at my local GM dealer, and discovered this leak:



Which is good, because that's where I could hear it hissing from last night and has confirmed I'm not going crazy.

The parts guy told me the o-ring only came with a new AC hose. I knew he was talking out of his arse, so I called another dealership. This one told me it was discontinued, but I could get one from their Oklahoma branch if I didn't mind a short 159 mile trip. I decided to try my luck in the plumbing section of Home Depot instead. I picked up a pack of #10 o-rings that was half the price a single OE o-ring would have cost me. My only reservation is whether the PAG oil will react badly with them as I doubt they're nitrile. Only time will tell.



After replacing the o-ring, I pulled a vacuum for half an hour and watched the needle bottom out at 30 inHg. Things were starting to look up. I closed the manifold valves, switched the pump off and, after another half hour wait, the gauge looked like this:



Success! I now had an airtight system, and it was time to charge it up. I put the key in the ignition, turned it and heard nothing but a faint 'click'. Looks like I'd left the trunk or a door open overnight. A quick check with the multimeter confirmed the battery was pretty flat:



So now I've a 10-12 hour wait while the battery charges, but things are at least heading in the right direction now.

One thing that occurred to me was that the radiator fan has never once kicked in. Is it meant to when the compressor is on, or only when the radiator thermostat dictates it?

[PoisonIvy]

Awesome! I love reading the story with pics. I think I've learned a little about the a/c system. Hopefully the next chapter is the happy ending part.

[xintersecty]

That is Something AWESOME! So glad for you! The ring will hold up. My pack of O rings came in a bunch of sizes. The green rings you were displaying are meant to go around a fitting and not in. And yes, the stupid battery dying when fixing something has bit me too with car and boat.

[The_Limey]

So, armed with a charged battery and two 12 oz cans of R134a, I was determined to finally finish this thing. I weighed both cans with the tap included and got 18.4 oz for each. I needed to charge the system with 18 +/- 1 oz, which meant completely emptying the first can (easy) and some how extracting 7 oz from the second can (not so much). This would give me 19 oz total, which I thought would probably put me in the right ballpark considering I was bound to lose some refrigerant to the gauge hoses.

I fired the old girl up, flicked the AC on and opened the LP manifold valve up. After a minute of shaking the can and watching the spyglass on the gauges, the can seemed to be empty.



18.4 - 12 = 6.4 oz when empty. 6.5 oz isn't bad! So there's now 11.9 oz in the system. Next up was the tricky bit. Somehow trying to guess how long it takes for the system to inhale 7 oz of refrigerant. I hooked it all up, opened the valves and shook the can for about 20-30 secs and shut it off.



By some small miracle, I ended up with a can and tap weighing 12 oz.

18.4 - 12 = 6.4 oz of R134a.

11.9 + 6.4 = 18.3 oz in the system. I was pretty happy with that. From everything I've read, it seems slightly undercharged beats overcharged. As I said, I expect I've lost some refrigerant to the hoses, but I'm not gonna bother trying to calculate how much.

I packed all the equipment away, grabbed my trusty thermometer and filmed this maiden voyage.



This was with the fan on the first setting, and the temperature at minimum. A 30 degree drop in under 2 mins says I've finally fixed the AC!

And they all lived happily ever after.

THE END.

[PoisonIvy]

Nicely done! And a happy wife, just in time for summer.

[xintersecty]

Congratulations! I am glad I encouraged you to do the job yourself. You now have two additional tools in your kit, gauges and vacuum pump (great for model making). The most important tool you have is knowledge and freedom from the oppression from the consumer machine (the dealers). Considering we have two cars in most families here in an america that means the tools will not be wasted.

I am very glad to read a happy ending story. Just be careful, I know the author will be back with some other disaster story such as The revenge of the G3 or maybe The G3 Strikes Back.