[mousefarmer]

2006 BMW 330i

The car is starting to get like my 2005 Civic did when it was running low on refrigerant: when sun hits radiator air starts feeling warmer then when shade is cast over it, it gets cooler again. I took Civic to place a couple of years ago and they sucked out the refrigerant, ran vacuum on it and added refrigerant.

Is this common with e90s that refrigerant slowly leaks out over time and has to be added?

[Fiasco]

I'm also interested to know this, my AC was blowing warm but after a couple days in the garage its blowing a bit colder but still not as cold as it should. I bought an AC recharge bottle (12A refrigerant with dye) from Canadian tire and the prevailing YouTube knowledge says to pump some into the low pressure valve under the hood.

Is it nessecary to have the old stuff sucked out? If so what do I need to do that? Dont mean to hijack the thread just want to lay my thoughts out for when the AC experts arrive haha.

[mousefarmer]

AC systems run under vacuum so to have the most efficiency, the system should run under vacuum and with refrigerant flowing thru the vacuum.

If the system is slowly leaking out over time, then the refrigerant that is leaked into the atmosphere is likely replaced with air from outside the system which contains moisture. This can make it hard for the compressor to work and the moisture can start destroying the AC system. The system will run less efficiently and may be damaged in the long run as a result.

That is why I prefer to evacuate the refrigerant in the system which is likely polluted with outside air, pull the vacuum then add the refrigerant under the vacuum. Here is US, that usually means taking it to a shop and having them do that as the refrigerant has to be properly evacuated using a special machine which isn't cheap. When I had it done to my Civic it cost about $95 USD for this service but has worked perfectly since.

[relative4]

Originally Posted by mousefarmer

the refrigerant has to be properly evacuated using a special machine which isn't cheap.

Vacuum pumps and gauge manifolds are cheap and can be borrowed from auto parts stores.

[ccyccm]

The weather recently became cooler in my area and my AC started making a groaning noise, exactly like this video I’m going to link. Does anyone have any insight on curing this problem with an evacuation and recharge?

[Tambohamilton]

Originally Posted by mousefarmer

AC systems run under vacuum so to have the most efficiency, the system should run under vacuum and with refrigerant flowing thru the vacuum.

If the system is slowly leaking out over time, then the refrigerant that is leaked into the atmosphere is likely replaced with air from outside the system which contains moisture. This can make it hard for the compressor to work and the moisture can start destroying the AC system. The system will run less efficiently and may be damaged in the long run as a result.

That is why I prefer to evacuate the refrigerant in the system which is likely polluted with outside air, pull the vacuum then add the refrigerant under the vacuum. Here is US, that usually means taking it to a shop and having them do that as the refrigerant has to be properly evacuated using a special machine which isn't cheap. When I had it done to my Civic it cost about $95 USD for this service but has worked perfectly since.

Eh?? Sorry, but what a load of nonsense!

AC systems run pressurised, not under vacuum. How could they run under vacuum, and contain refrigerant at the same time? So when refrigerant leaks, as will happen very gradually on any car, it is not replaced by air or moisture...not until the system is extremely low on refrigerant, by which point the AC will not function at all.

The reasons for vacuum evacuating an AC system are:
1. To fully empty the system of anything that's in there - normally just refrigerant and lubricant. If a component on the AC loop had been replaced, there would also be air and moisture in there too.
2. To test for leaks; the vacuum is held for a period of time, and monitored to ensure that the system is not leaking.

Refilling a completely emptied system is the best way to ensure that the correct amount of refrigerant is in the system; relying on the pressure gauges to indicate when it is full is much less accurate, since system pressure doesn't vary much until the amount (mass) of refrigerant is very low (or far too high).

Bear in mind that venting refrigerant to atmosphere is illegal pretty much anywhere, because it's highly polluting.

[Tunafish]

Yes get the system evacuated and refilled will stop the noise. It did with my car.. Cost 160 but heard its cheaper in bigger cities..

[mecheng77]

If you are slightly low on refrigerant I don't think the system can take on air as pressure goes from high to low not the other way around. I needed a slight top up last year and just used my gauges and didn't vacuum it.

If you have a serious breach then yes absolutely you need to pull a full vacuum and you can use the weight recommended on the hood.

That's my two cents

[ccyccm]

Originally Posted by Tunafish

Yes get the system evacuated and refilled will stop the noise. It did with my car.. Cost 160 but heard its cheaper in bigger cities..

I appreciate the reply, thanks man

[Tunafish]

It might only needed topped off... I had 1.14 pound with a capacity of 1.37 pound when it was making groaning noise. I went with the evacuation so i knew it was to specs, you can get it close with topping off using pressure method but that is a crap shoot that i dont want to loss sleep over.. Plus i now know that i lost .23 pounds in 8 years which is within permitted specs.