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

Since my wife bought the car from Hertz, the AC has never worked properly. It's just not very cold. She took it to Pepboys to have a leak test conducted and they told her (amongst a host of other things that needed replacing) there was zero pressure in the system and it required a new condenser and compressor.

Having purchased both new parts, I disassembled the front of the car and as I unhooked the pipe exiting the condenser (on the dryer side) there was a huge release of pressure and PAG oil which almost gave me a heart attack. Now I'm thinking there's no leak in the condenser as there's no sign of dye anywhere, and at just over three weeks since the test there's evidently still a lot of refrigerant in the system.

I've decided not to replace the parts, but go back to diagnostics and re-checking the basics. I've checked all the fuses and with the AC turned to 4 and the coolest setting, I can hear the compressor clutch click and kick in.

Can anybody suggest something I might be missing? I've read about jumping the pressure sensor, but surely if the compressor is kicking in this must be OK?

Have you charged the system yourself with a home kit? Did you put dye in it yourself to find a leak?

No, this was done by Pep Boys.

Your post are misleading. It sounds like they did not fill the system and yet you had pressure and then they filled the system. So did they really fill the system?

1) you need good air flow across the evaporator coil (the one inside and makes the car cool). Have you check the air filter for the AC?

2) When you took the system apart did you allow it to completely dump? Or did you shut it down right away?

3) Most Car ACs has two pressure switches. The High Pressure acts as a safety. The low pressure is what controls the compressor. The liquid freon goes to the expansion valve or orifice as it expands it takes heat out of the evaporator. Meanwhile the compressor is sucking and compressing the gas. If there is not enough heat to expand the liquid into gas then the low pressure cuts off the compressor until there is gas to compress.

So that means until pressure goes up, then compressor will not run.

4) Buy a AC gauge kit. Well worth it to have. You should be able to see low pressure side changing up/down to cause the compressor the cycle.

5) If you compressor is running however it's not cooling then you might have an airflow issue OR a bad low pressure switch stuck on.

I'm just as confused as you are about what Pep Boys actually did to the car. According to the quote, both high and low pressure readings were zero. They charged us for dye and refrigerant, and supposedly leak tested the whole system. I think they realised my wife wasn't technically minded, did none of this, and simply quoted for the two most expensive and labour intensive parts to replace. They also said the front struts and rear shocks needed replacing (based on mileage?!), and the power steering circuit was leaking.

I'm really of a mind to just do this myself now. I'm not sure I trust garages any more. Unfortunately, due to the shock of there being a whole load of pressure still present in the system, I allowed it to totally vent along with a load of PAG oil. If I recharge the system myself and buy some AC guages, what values are typical for the high and low pressure valves? From what you said, I'm planning to replace the dryer and cabin air filter and go from there.

Quote:

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Originally Posted by The_Limey

I'm just as confused as you are about what Pep Boys actually did to the car. According to the quote, both high and low pressure readings were zero. They charged us for dye and refrigerant, and supposedly leak tested the whole system.

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I had the dealer pull some crap like that on my ford. i took it the dealer for oil changes, they said my brake pads were shot. So I replaced myself, found out my pads were at half of service life. I took my spent pads to the same dealership and asked them stop lying to me and refund my oil change money. They did and lost my business for life.

Goto pep boys and ask for a refund as it stands now because of their lying, you have a more expensive repair.

To do AC work you will need a set gauges and a vacuum pump.

Guages
Get a set of gauges that show negative pressure, so that will run the cost a little more. These are well worth it for charging and keeping your friends happy.

Vacuum pump.
Here is a cheap O pump that requires shop air from harbor fright. Requires a lot of shop air, a lot.
Vacuum Pump - AC Vacuum Pump w/ R134A & R12 Connectors

If you can afforded get a real pump. They are useful pulling vacuum if you do any modeling.

The vacuum is essential for putting together a good system. It takes the moisture and contaminants out of system that will ruin the gas and compressor.

I say do the repair your self. You learn something and be set free!

And besides if the GD compressor was shot, they would have not been able to recharge the system. So they are really lying.

OK. Looks like I'm going to try and return the compressor and condenser. Luckily I didn't fit them or anything, just opened the packaging, so it should be OK.

My father-in-law has a fairly industrial-sized air compressor, so I should be OK to buy that pump you recommended. They also have a sale on a set of gauges:

AC Gauges - Save on this AC Manifold Gauge Set

Is there a rough how to guide on recharging AC systems? I'm pretty familiar with motorbikes, but this is the first car I've owned and have never tackled AC systems before. I assume I'm attaching the gauges to the two valves near the bulkhead, but am I recharging through these as well? How do I deal with the lost PAG oil when I opened the system? Can I just recharge it with an oil/refrigerant mix or does it need to be exactly the c. 200ml recommended by GM?

Edit: I've just discovered Scotty Kilmer's YouTube channel with a lot of AC repair videos. That's this afternoon's entertainment taken care of.

Quote:

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Originally Posted by The_Limey

Is there a rough how to guide on recharging AC systems? I'm pretty familiar with motorbikes, but this is the first car I've owned and have never tackled AC systems before. I assume I'm attaching the gauges to the two valves near the bulkhead, but am I recharging through these as well? How do I deal with the lost PAG oil when I opened the system? Can I just recharge it with an oil/refrigerant mix or does it need to be exactly the c. 200ml recommended by GM?

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It needs to be the 200ml. So I would just pressure everything out of there and start fresh. You basically put the oil in the system then take the vacuum down. It looks like those gauges show vacuum, then your good.

Those are good videos and do a bunch of reading. I bought a haynes book that explains everything. It also had numbers for everything. However that was years ago.

I love refrigeration as it's really about physics and thinking through the process. It's not easy but once you understand it, it's worth it.

Remember the process

cold gas -> compressed to hot liquid -> slightly cooler liquid after the condenser -> expansion valve -> takes heat from the evaporator -> cold gas

Rinse and repeat

I should really be much better at this than I am. I studied mechanical engineering at university, and had the refrigeration cycle drilled into me during our thermodynamics classes. It's just figuring out where everything is on this car and what measurements are considered normal. I'm gonna spend the rest of the day researching and then I think I'll have a crack at it.

Watch this space...

Quote:

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Originally Posted by The_Limey

I'm gonna spend the rest of the day researching and then I think I'll have a crack at it.

Watch this space...

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Take pictures and share on the forum. And don't forget to check your fan inside the car

Yep. I'll do that when I replace the cabin air filter. One quick question: if I'm removing moisture from the system via vacuum is it still crucial I replace the dryer?

Thanks ever so much for your help, xintersecty (or should that be Origin?). Sometimes it helps just to have a gentle shove in the right direction.

Quote:

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Originally Posted by The_Limey

Yep. I'll do that when I replace the cabin air filter. One quick question: if I'm removing moisture from the system via vacuum is it still crucial I replace the dryer?.

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You have to replace the dyer. It's contaminated. They need to be replace ever so often as moisture get's into the system. Or trap the moister that got introduced in the first place. Here is a short read:
Air Conditioning Dryer

A longer read and much better:
Auto Air Conditioning - Replacing your auto A/C compressor

I took my name as it's mathy and kinda cool. I will admit I suck at math. I got to differential calculus and my f'ng head exploded.

So today was a long old day and I'm left feeling like I didn't really get anywhere. Two things really held me up: removing the serpentine belt and the radiator. Despite using all the magic words at them, I still had to go and make a cup of tea before I managed to get anywhere with them. I took a shedload of pictures, mostly to remind myself where stuff went, so I won't bore you with them all. The short version is, I now have a car that looks like this:

http://i130.photobucket.com/albums/p...psa783gixx.jpg
http://i130.photobucket.com/albums/p...psi9qjm9ua.jpg

and a pile of bits that looks like this:

http://i130.photobucket.com/albums/p...psubjc7jyl.jpg

I'm still not convince whether the compressor works or not. There's no signs of leaks anywhere having visually inspected everything I've pulled out so far. I went to empty the PAG oil out of the compressor, turning it by hand over a bucket, and there was nothing in there. Not a drop. Which worries me. I'm gonna flush everything out tomorrow and look for metal particles in the solvent. The expansion valve looks clean to me, but I'm not really sure what I'm looking for other than obvious metal particles:

http://i130.photobucket.com/albums/p...psokdsuupt.jpghttp://i130.photobucket.com/albums/p...pssoskmhuw.jpghttp://i130.photobucket.com/albums/p...psytxtweaw.jpg

I drained the coolant and had a moment of panic when it came out an orange colour. I thought it was rust before a bit of research revealed these cars come with Dex-Cool which is orange.

http://i130.photobucket.com/albums/p...psvzuyz4oe.jpg

On a slight positive note, when I removed the cabin filter it was filthy, so there's at least room for improvement there. I've read a lack of air flow across the evaporator can hinder cooling performance, which makes sense.

http://i130.photobucket.com/albums/p...psy3tvv9xk.jpg

Tune in for part 2 tomorrow...

Very good. Sometimes the expansion valve is just a orifice, a fixed sized hole. That allows the liquid to expand as a gas and works as a throttle.

No oil in compressor is bad, very bad. Plan on getting a new one.

You are doing great.

Well, here's the thing. I have a new one and a new condenser. Should I just fit them and be done with it?

Quote:

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Originally Posted by The_Limey

Well, here's the thing. I have a new one and a new condenser. Should I just fit them and be done with it?

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I would. Granted it's more money, but having a happy Air Condition Wife is priceless. Considering the condenser fins are beat up, replacing it is not a bad idea. Make sure you replace as many of the O-rings as you can on the different hoses too. I remember just buying a box of random sized o-rings, and I swapped them around the last time I did an AC job.

I'll probably go this route. I'm gonna hook the compressor up to a 12V source to engage the clutch and see if I can get any discernible suction/compression from it. Guess I should probably change the expansion valve to be on the safe side, too. I've got a 4 Seasons (I think) o-ring kit so I'll change everything when I reassemble it.

EDIT:

So the evaporator/cabin fan works.

https://www.youtube.com/watch?v=OmUj...ature=youtu.be

The compressor also seems to work:

https://www.youtube.com/watch?v=ZIZuATD7iaU

although when I turn it by hand there's a bit of scraping (probably due to it being devoid of any oil) and comparing compression to the new part I have, it's no where near as strong. With the ports plugged, the new one is significantly harder to turn by hand.

I'm just going to bite the bullet and change the compressor and the condenser. I'm off to buy a new expansion valve, too. More updates later tonight, hopefully.

Sorry for the lack of an update recently. Things haven't gone exactly according to plan. So, after stripping everything out and fannying about with the compressor, I decided to just play it safe and replace it along with the condenser/dryer and expansion valve.

http://i130.photobucket.com/albums/p...pslvtj03uq.jpg

And all the radiator plumbing back in place with new coolant added:

http://i130.photobucket.com/albums/p...ps6pc7s3mq.jpg

Next, I hooked this bad boy up to some shop air

http://i130.photobucket.com/albums/p...psvfzk1bgm.jpg

and set about flushing all the pipework through

http://i130.photobucket.com/albums/p...psotl7dy6z.jpg

which left me with a bucket of solvent that looked a bit like this:

http://i130.photobucket.com/albums/p...ps6ajuh7x7.jpg

Having discovered that removing the evaporator would entail the entire dis-assembly of the cockpit, I got a little creative and flushed it out in situ.

http://i130.photobucket.com/albums/p...pscnzdrmy7.jpghttp://i130.photobucket.com/albums/p...psxmchzdkb.jpg

Next up was fitting the new compressor with a fresh dose of PAG46 oil:

http://i130.photobucket.com/albums/p...psjlaygusg.jpg

All bolted back in and time to tackle the idler pulley. I employed a bit more leverage this time round and it slipped on much easier.

http://i130.photobucket.com/albums/p...ps1gdm9hbv.jpg

So, with all the nice shiney new AC parts installed, it was time to pull a vacuum. And this was where things stopped working out for me. It turns out my father-in-law's shop compressor was 20 years old and had probably never seen a service and, as a result, was a bit leaky.

http://i130.photobucket.com/albums/p...pspnftmadp.jpg

This leak got progressively worse until the motor on it was starting to smell like burning oil and it could barely sustain 70psi.

http://i130.photobucket.com/albums/p...psnttohd5g.jpg

I decided to put it out of its misery and unplugged everything with a vacuum barely below 22inHg.

http://i130.photobucket.com/albums/p...pssq3s5fkd.jpg

Feeling a little dejected that I'd come so far and couldn't finish the job, I popped down to the local garage to see how much they'd charge me to finish the job. They quoted me $99 which coincidentally was the same price Harbor Freight were charging for this single stage vacuum pump:

Electric Vacuum Pump - 2.5 CFM

I put the car aside after spending three full days on it, and contemplated my next move. Whilst weighing up the options, my father-in-law makes a call to a friend of his who has a machine shop built on the side of his house that would put most commercial garages to shame. Turns out he has a shop compressor with more than enough oomph to drive this crappy venturi type pump I have, and says if I drop round tonight with the car he'll give me a hand finishing the job.

Fingers crossed!

Good luck! I hope it works out tonight.

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:


http://i130.photobucket.com/albums/p...psurgbge7u.jpg

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.

http://i130.photobucket.com/albums/p...pscpy7ylak.jpg

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.

http://i130.photobucket.com/albums/p...pszemml4uc.jpg

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...

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.

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:

http://i130.photobucket.com/albums/p...psesms07u7.jpg

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):

http://i130.photobucket.com/albums/p...ps5menynlb.jpg

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).

http://i130.photobucket.com/albums/p...pszbbcxvxn.jpg

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.

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:

http://i130.photobucket.com/albums/p...psdeakxy3w.jpg

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.

http://i130.photobucket.com/albums/p...pscnsl3myv.jpg

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:

http://i130.photobucket.com/albums/p...psqp0nygz2.jpg

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:

http://i130.photobucket.com/albums/p...pson4xbjpm.jpg

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?

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.

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.

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.

http://i130.photobucket.com/albums/p...pskasabd3f.jpg

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.

http://i130.photobucket.com/albums/p...psxnomg8np.jpg

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.

https://www.youtube.com/watch?v=Or92cyAgFKI

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.

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

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.