A/C Troubleshooting

Technical info on the Pontiac Vibe and Toyota Matrix including do-it-yourself info
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cthomasparr
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A/C Troubleshooting

Post by cthomasparr »

I have a 2004 Vibe and the A/C was not blowing cold. I charged with A/C Pro and the compressor engaged, so the common thread here for the compressor clutch is not an issue. Still no cold air. I get the increased engine load and RPM change that lets me know that he compressor senses the system is charged and the relay and compressor are working. Does the level of charge make a difference. I am in the green zone, but on the low side. I think what is left of my A/C charge canister is at that pressure, so to increase I need to break open a new can... even though that one still has fluid.

Any other things I can check? Thanks
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kumquat
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Re: A/C Troubleshooting

Post by kumquat »

The level of charge makes a big difference, yes. Knowing the low side pressure alone doesn't really help much actually: you need to know the high side pressure, and the ambient temperature, to figure out what's going on.

Did the compressor fail to engage until you added a can? If the system was empty, a full fill takes about 24 ounces of R134. But if the refrigerant leaked out, you also need to add oil to the system. If you don't have enough oil in there, the compressor will destroy itself just like an engine would.

If you added refrigerant to a system that was already full, that's bad too. It could have been the TXV, a failing compressor, or something else.
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

thanks kumquat. This is the layman's recharge. It takes into account ambient temp and low side pressure. I think it contains oil in the mix, although maybe not the recommended amount for an empty system. Is there any chance that the oil is still stuck in the lowest point near the compressor??? I didn't see any dirty oily residue around there that would indicate a leak by the compressor.

The instructions on the can is to "empty" the freon without overcharging and then turn the can over and fill. Not sure if that last step is to get oil out of the can or what its purpose is. My kit came with an additional small can... maybe 12oz. I can probably attempt to get the pressure up with that can.
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kumquat
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Re: A/C Troubleshooting

Post by kumquat »

GM provides a whole chart of how much added oil is needed depending on the type of failure or component being replaced. You need like 2 ounces for a hose blowing, but 4 ounces when replacing a compressor.

Anyway, if there was a leak in the system adding a can of R-134a won't fix the leak.
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trb
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Re: A/C Troubleshooting

Post by trb »

One of the other things to consider is if the system had a leak, it could have filled up with regular air and then it will not take a full freon charge. I did that on my first AC repair, and it never quite worked right. Now, unless I know a system was just a bit low, I usually pull a vacuum on the system to pull out all of the air and most importantly, any moisture in the system. Pulling a vacuum and making sure it holds for a while, like a couple of hours with the pump off and the pump valve closed, is also a good way to make sure there is no leak in the system. Then I can refill it with the required quantity of refrigerant. Luckily AutoZone and a few other parts places rent out the vacuum pump and manifold gauges to properly recharge the system for free. You pay for the tools and get a refund when you return them. So if you have a place like that close by, that is your best bet.

Good luck and if you have more questions, just ask.
Thomas
the "Mustang Guy"
1987 5.0 LX Mustang
2016 Mustang GT - current daily
2004 Satellite Vibe &
2009 Red Vibe GT -twin's cars
2003 Neptune Vibe GT - prior daily
2010 Red Vibe GT - RIP 6/16/14
2006 Platinum Vibe - son's car
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

Good advice. I had taken an older ford taurus to a A/C repair place looking to get a retrofit. Long story short, they say they pumped in very expensive R12 and heard it hissing out. Leaking receiver/dryer and possibly other places. Got a bill for $200 and wondered if they could have done the vacuum trick or just filled with air prior to evacuating. I trust that A/C repair places have the knowledge to do the job correctly, but I don't trust them.

Charging a system that has a leak doesn't make a lot of sense except for the claim that every DIY charge product promises to fix leaks and lubricate seals. In my opinion worth throwing $50 at. It has worked at least for a little while on other cars.
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kumquat
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Re: A/C Troubleshooting

Post by kumquat »

cthomasparr wrote:Good advice. I had taken an older ford taurus to a A/C repair place looking to get a retrofit. Long story short, they say they pumped in very expensive R12 and heard it hissing out. Leaking receiver/dryer and possibly other places. Got a bill for $200 and wondered if they could have done the vacuum trick or just filled with air prior to evacuating. I trust that A/C repair places have the knowledge to do the job correctly, but I don't trust them.

Charging a system that has a leak doesn't make a lot of sense except for the claim that every DIY charge product promises to fix leaks and lubricate seals. In my opinion worth throwing $50 at. It has worked at least for a little while on other cars.
Those leak stop things never, ever work. If you're going to dump something in there, put some of the stuff with UV dye then go in at night with an LED light to see if you can find the leak. Otherwise, just pay a mechanic the money to use their special leak detection machine.
pushead
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Re: A/C Troubleshooting

Post by pushead »

I you search around you can find a few good shops that can diagnose your problem while you stand there. Then decide if its a job you can fix on your own or not. I do all my own work until yesterday. My vans a/c went out I took it to a place down the street, he found the failure for free. He pulled up the autozone page to show me the parts and cost (yes I know he gets a reduced rate). I told him I was going to shop the net because I thought I may find the compressor a little cheaper and do it my self. He called his account rep and begged for a discount. I got all the same compenents I would have to buy and replace from him installed for $50 more than I could do it myself that was not including my time. So depending on your needs I would shop around. It helps if you can show them you know what you are talking about so they can not bs you and if the shop or person is hungry.
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

Good advice.

I think I may investigate trying to find a leak using the UV filler before I go anywhere. Don't want a shop selling me a compressor and some other big dollar parts if I don't need them.

Would be nice to have the specs should I decide to repair.

I just took a quick look at Rock Auto and saw the assortment of o-rings and parts that can be replaced. Certainly seems like a place where you can throw money at a problem. I guess if I find a obvious leak I might try a repair myself... not sure.
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kumquat
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Re: A/C Troubleshooting

Post by kumquat »

Most shops won't try to sell you parts you don't need. Be careful of falling down the rabbit hole on ACs though. Refrigerant is expensive and it's easy to end up buying and using $100 worth of the stuff and ending up no better than where you started. My mechanic charged about $70 to put a couple cans in and use his fancy machine to identify specific leaks. Saved me a bundle.

Also, if the system has been open to the air you need to vacuum the system before filling it, and you need to replace the receiver/dryer.
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

I am going to give this a try myself.

Will purchase a manifold set and vacuum today. I may also replace the receiver/dryer. There is a Delphi braded model that is around $20 RD10006. Will swap receiver dryer, vac system for 30 minutes or so, check if it holds vacuum and then add refrigerant and dye. Sticker on hood says 1.34 to 1.48lbs of refrigerant and oil is RL-897 or equiv. So looks like 22 - 23.5 ozs refrigerant. Not sure about the oil. I need to investigate if RL-897 is readily available, if there is an equivalent PAG# and quantity required for a replaced accumulator dryer. I plan on using refrigerant on - hand A/C Pro 10oz. and pick up a refrigerant with dye Interdynamics Arctic Freeze Ultra Synthetic R-134a Refrigerant (12 oz.). That should get me to an acceptable fill. Sound reasonable?

I think I will be left with a slow leak that hopefully will show up with the dye. Even better if I get a season or more out of this charge.
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kumquat
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Re: A/C Troubleshooting

Post by kumquat »

Your car calls for Pag 46. You can get it at your local auto parts store. Just buy one of the 8-ounce bottles.

When replacing the receiver dryer, add 2 ounces of oil directly to the component. I'd add an extra ounce for anything you may have lost with the leaks.
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

Thanks kumquat. I hope to get to it this weekend and I will post results. I had also read about o-ring sealant specified as nylog red or blue... something like that. I am going to see what the auto parts store suggests. I am just concerned with the o-rings for the reciever dryer.
cthomasparr
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Re: A/C Troubleshooting

Post by cthomasparr »

I had limited success with the a/c recharge.

I didn't replace the receiver drier, but did put in a fresh charge of freon and dye... also added about 1oz of oil PAG 64.

The air is cool to cold which is great, but I was not satisfied with my purge of the system. I used a venturi type suction device that ran off my air compressor, which is a 220V 22 gallon, so seemed large enough for the task. I was able to get about 22-24 inMg and no more. I even tried to close off the low side and only apply vacuum when the compressor was at 90psi or better.

When I need to get back into the system and replace any parts of fix a leak, I will probably choose a mechanical vacuum pump and do a better purge.
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trb
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Re: A/C Troubleshooting

Post by trb »

Using a mechanical vacuum pump you should be able to draw it down to almost the max on the gauge, like 29 or so. I ran it for several hours to really dry it out. Good luck on it!
Thomas
the "Mustang Guy"
1987 5.0 LX Mustang
2016 Mustang GT - current daily
2004 Satellite Vibe &
2009 Red Vibe GT -twin's cars
2003 Neptune Vibe GT - prior daily
2010 Red Vibe GT - RIP 6/16/14
2006 Platinum Vibe - son's car
cthomasparr
Posts: 134
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Re: A/C Troubleshooting

Post by cthomasparr »

Just wanted to follow up that the vibe AC is doing well after two years. Unfortunately my other vibe now has lost its ac and I will be replacing the compressor based on lack of pressure difference between the low and high side and will also replace the receiver dryer, vacuuming the system and adding oil and refrigerant. Going to go cheap on this one and have a used compressor on the way. Car has over 250K miles, so don't want to sink 500-600 into the ac.
Jeff2
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Re: A/C Troubleshooting

Post by Jeff2 »

cthomasparr wrote:Unfortunately my other vibe now has lost its ac and I will be replacing the compressor based on lack of pressure difference between the low and high side and will also replace the receiver dryer, vacuuming the system and adding oil and refrigerant. Going to go cheap on this one and have a used compressor on the way. Car has over 250K miles, so don't want to sink 500-600 into the ac.
Could be the clutch on the compressor. Somewhere on these forums I read that this is a fairly common problem with these cars. If that is the problem, replacing it should be cheaper than replacing the entire compressor.
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