AC Recharge
#1
AudiWorld Senior Member
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AC Recharge
When I first got my car in July 2009...it really annoyed me when the car would control the AC because it'd cycle from no air flow at all (or a dose of outside air) and when the temp got above the setpoint, it'd blast me with ice cold blasts of air (since it controlled the fan speed too).
Felt like I was having hot flashes or something.
Got in the car today, and it was 90F outside, and while the AC air is still cold, it's not as ice cold as it was before.
Has anyone done an AC/refrigerant recharge? Is it as simple as going to Autozone and buying the can with the pressure gauge and refilling it to a certain PSI?
Felt like I was having hot flashes or something.
Got in the car today, and it was 90F outside, and while the AC air is still cold, it's not as ice cold as it was before.
Has anyone done an AC/refrigerant recharge? Is it as simple as going to Autozone and buying the can with the pressure gauge and refilling it to a certain PSI?
#2
No. It is not that easy. You need a vacuum pump to pull down the system to remove any moisture from the system. At the same time you need to make sure that the vacuum holds, meaning no leaks in the system.
You then need to charge the proper amount of HA134 by weight, and verify the low and high side pressures are correct.
Of course you need a manifold pressure gauge set, and to follow the rules a recovery system for the used refrigerant.
You would also need VAGCOM to examine the temperature and pressure sensors for correct operation.
A quality shop is well worth the price to have it done.
You then need to charge the proper amount of HA134 by weight, and verify the low and high side pressures are correct.
Of course you need a manifold pressure gauge set, and to follow the rules a recovery system for the used refrigerant.
You would also need VAGCOM to examine the temperature and pressure sensors for correct operation.
A quality shop is well worth the price to have it done.
#3
AudiWorld Senior Member
When I first got my car in July 2009...it really annoyed me when the car would control the AC because it'd cycle from no air flow at all (or a dose of outside air) and when the temp got above the setpoint, it'd blast me with ice cold blasts of air (since it controlled the fan speed too).
Felt like I was having hot flashes or something.
Got in the car today, and it was 90F outside, and while the AC air is still cold, it's not as ice cold as it was before.
Has anyone done an AC/refrigerant recharge? Is it as simple as going to Autozone and buying the can with the pressure gauge and refilling it to a certain PSI?
Felt like I was having hot flashes or something.
Got in the car today, and it was 90F outside, and while the AC air is still cold, it's not as ice cold as it was before.
Has anyone done an AC/refrigerant recharge? Is it as simple as going to Autozone and buying the can with the pressure gauge and refilling it to a certain PSI?
#4
Adding Freon to a low system is acceptable for testing purposes, but your car will suffer "the black death" from aluminum oxide if you allow the system to run very long with air inside. The fix then is to change ALL the components touched by the refrigerant.
It is better to fix leaks than to depend on sealers. There is no mechanic-in-a-can. I will use ultra-violet dye to find leaks if a vacuum will not hold and the usual suspects don't have any signs of leaking.
#5
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But while I don't believe it's necessary to vacuum down a system that still has positive pressure, I would still take it to a shop that has the proper equipment to accurately charge it. The bigger danger is overcharging the system. The simple act of adding too much refrigerant can change saving $75 into costing > $1k.
#6
AudiWorld Senior Member
Technically, all automotive HVAC systems are open systems. The shaft seal is not a perfect hermetic seal. It is normal for trace amounts of refrigerant to be continually lost. If his AC is still running and producing even slightly cool air, then there's enough pressure in the system to satisfy the safeties, enough pressure to create at least some refrigeration effect, and enough pressure that there shouldn't be air in the system. As long as the pressure is positive relative to the atmosphere, refrigerant will continue to leak out, not air leaking in.
But while I don't believe it's necessary to vacuum down a system that still has positive pressure, I would still take it to a shop that has the proper equipment to accurately charge it. The bigger danger is overcharging the system. The simple act of adding too much refrigerant can change saving $75 into costing > $1k.
But while I don't believe it's necessary to vacuum down a system that still has positive pressure, I would still take it to a shop that has the proper equipment to accurately charge it. The bigger danger is overcharging the system. The simple act of adding too much refrigerant can change saving $75 into costing > $1k.
#7
According to the SAE Audi loses less than 14 g/year. That is about half an ounce. The greater portion of the loss is through the pores in the hoses, not the shaft seal. Audi has the compressor manufacturer perform a 100% helium leak test. If helium can't pass the refrigerant does not stand a chance.
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#8
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After four years he still has enough refrigerant to cool, even if it's not cooling as well as it did when new. So if he has a leak, it's not a huge one. These have fairly small refrigerant charges, a relatively small loss of charge can affect performance.
#9
AudiWorld Senior Member
Thread Starter
OK!
The car still makes plenty of cold air. I don't have a system leak. I think I've just lost a bit of refrigerant over the last 4 years.. which is NORMAL, and was wondering if I could top it off with the can. and it looks like if I check the pressure and it is low, then I can top it off with the can. That's all I needed to know.
No need to vacuum down the system or anything else silly and intensive right now.
The car still makes plenty of cold air. I don't have a system leak. I think I've just lost a bit of refrigerant over the last 4 years.. which is NORMAL, and was wondering if I could top it off with the can. and it looks like if I check the pressure and it is low, then I can top it off with the can. That's all I needed to know.
No need to vacuum down the system or anything else silly and intensive right now.
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Tim Baker (07-05-2020)
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