Servicing the AC system
 

We can keep this a running thread with AC diagnostics/fixing.

Here's my situation. Small AC leak when I bought the car 5 years ago. Filled it that summer and worked. Didn't work the next summer. Didn't touch it for 4 years. This summer I filled it again with one of those DIY kits. Worked OK (not ice cold) for a couple weeks until the condenser burst. I think it's because my AUX fan failed to turn on and it overheated.

This means I now have an open system and moisture has come in. In retrospect, I should not have filled what was likely an open system with moisture in it. Hopefully I haven't prematurely killed my compressor.

Here's the plan:

Acquire new condenser (done)
Acquire new receiver/drier
Acquire new O-ring seals (other than the ones at the evaporator which I figure are difficult to replace)

http://realoem.com/bmw/diagrams/e/i/20.png
Link to o-ring diagram

Lube o-rings with refrigerant
Replace condenser along with new o-rings
Replace all other o-rings
Vacuum system out for 1-2 hours
Check if vacuum holds
Replace receiver/drier
Vacuum system out for half an hour
Fill with oil and proper weight of refrigerant (amounts?)


Enjoy ice-cold AC.

I don't think I will be able to vacuum it myself but if I get a shop to do it, I'll have to come back for the second vacuum after I replace the receiver/drier. I don't want to replace the receiver/drier and do just one vacuum because I'm afraid it'll trap all the old moisture and again, be useless. Also, I don't know if any shop will vacuum it for at least an hour... Any hookups here would be great.

Comments/suggestions/links for parts?

Ordered this receiver drier and this O-ring kit.

Since everything already leaked out, you don't need to vacuum it before fixing, just change the parts and get it done after and check to see if there are any other leaks before filling it.

Also it might be a good idea to put some dye in the system so that if there is a leak the dye will help find it.


Also if you really want to do it yourself, there is a DIY R134a & R12 vacuum selling in the US, haven't seen them in Canada yet. It requires a compressor. I'm not sure how good of a job it does, I doubt it will be as good as getting it done at a shop:

http://www.harborfreight.com/air-vac...ors-96677.html

Thanks. Yea I think I'll leave the filling to the pro's this time.

From what I've read, you should always vacuum to get rid of moisture that entered the system. If left in there, it will react with the refrigerant and corrode the lines and compressor. Some even recommend vacuum, fill with nitrogen, vacuum, and then fill with oil and refrigerant.

Correct. This is the same process my buddy uses at his shop.

The only problem I had with him was his guessing of how much to put in, or his tell me when the air is blowing cold theory lol (I guess he still has a little back yard mechanic in him lol)

After he filled it the first time with his guessing theory it created a load that was very noticeable (especially when down shifting or coasting to an intersection light), which was Due to him putting to much free on. It also didn't help my fuel consumption when it was in use. I was getting like 250-300kms a tank!

We re did the process according to specs and the strain/load that the compressor was producing was gone.

the amount will vary depending on system. there should be a sticker near by or on the compressor indicating how many ounces the system takes.

Also, vacuuming out the system is required because if air is in the system you won't be able to adequately charge it. No room for the freon. Taking the moisture and air out allows for the right amt of freon to enter the system. Better to under charge it slightly then over. Over taxes the system and o-rings. the compressor body itself independently has about 4 oz of oil in it. then about another 2 oz gets pushed into the system. Again best to check with labels or call the dealership and find out.

Can you add oil straight to the compressor without taking it out? Is this even necessary or can all the oil be pushed through the lines?

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Did compressor/condensor/drier myself last year. Pretty easy bolt-on DIY. Mine was only discharged over the winter from SEP thru APR and I didn't bother with vacuuming the system. However, when I opened it up initially, it still had a noticeable amount of pressure in it so vacuuming is probably good to do. My compressor was OEM from Bimmerspecialist (pre-filled with oil). The drier was Febi from GermanParts.ca. The condensor was a Nissens from Autopartsway. The Nissens was noticeably lighter than the OE condensor, plus it was missing some mounting brackets which I had to fab up. Just replaced the a/c microfilter this year along with a faulty blower resistor (no low speed blower) and everything is chilly.

Pretty good price on both your drier and o-rings (... for that price, you would only be able to get 2 o-rings from the $tealer!)

Yes I know I called the dealer haha. Much better with the maxbimmer discount at Maranello but still a bit cheaper on autopartsway.

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Yes, you can. The big square o-ring in your kit is for the top plate on the compressor where the lines go into it. My new pre-filled compressor had the oil in there and it was pretty much full to the top. When you change that o-ring, you can fill it with oil. I think the spec'ed amount is in the Bentley.

BTW, I lubed my o-rings with refrigerant "oil", not refrigerant (but that's probably what you meant).

The ones at the evap aren't that hard to get to, depending on your level of dexterity and patience. My A/C is holding up, charged it last year with a DIY can kit, but it doesn't feel as cool as I would like when it's really hot out there.

Filled my system with a crappy tire kit this summer too. Blows ice cold while I'm moving or revving the motor, but sucks at idle :mad:

Got mine pro filled, blows ice on idle + driving. Idk works good.

Is your aux fan working?

Yes it isn't heat related.