Home A/C repair

[Steve N]

Got a DIY question for the group.

1993 525i Touring. The air blows cold and everything works fine when it is charged. Problem is, it leaks. I used a dye and found that it is leaking at the compressor where the high and low pressure hoses attach.

Looking at the parts diagram I see a small O ring in both spots. Keeping in mind that this is a 200k mile car, can I just unscrew the 2 hoses put in the new O rings, recharge and go? What potential damage can I do? Anyone know what size allen head is needed?

-Steve

[Jon K]

Thats about all you have to do - you will lose a ton of refrigerant however. I think its a 6mm, maybe 7mm... i took mine off a couple weeks ago. If you want new hoses that do not leak let me know I have them all.

[Rus]

Generally its best to let a shop remove the refrigerant from the system before you open it up. When you complete the repair, its recommended that you put the system under vacuum to remove any air, moisture, and contaminants that may be in the lines. Then you can charge it with refrigerant. Hope this helps.

[Tiger]

Ditto... you need to vacuum the system before refilling with refrigerant. You probably have R-134a already. You do need to evacuate system before taking that hose off. And yes, just the oring will do.

There is one other thing... try tightening it up more to see if it holds. Then you don't have to do the whole deal.

[Blitzkrieg Bob]

This will help ensure a clean and dry system

[rps1072]

If you open it, it will be relatively messy, but tolerable.
You might be able to find a shop that will let you supply your own refrigerant and only charge labor to vacuum and charge the system. I did this and they only charged me an hour of labor.

[rps1072]

Oh, and Bob's right about the drier--cheap part that should be replaced every time you open that system up.

[genphreak]

Oh, and Bob's right about the drier--cheap part that should be replaced every time you open that system up.Venting is bad- besides never open it without changing the dryer and never allow the drier to remain open to the atmosphere for long- it should be unsealed only immediately before fitting her in to the system. Do not open the system and then expect it to last if you let atmosphere or dirt enter and use it.

I'd tighten the connections 1mm or so (to move the thread) and take them up a bit to say what feels like around 50 ft/lbs, then clean and check for leaks a a day or two of use after that.

If you end up going into the shop, take a drier (new driers are $20 on eBay); most shops only charge for their time and the refridgerant they use... :) nick

[BigKriss]

what is a drier?

[Jon K]

pulls moisture out of the compressed gases

[BigKriss]

cool. Can you show me a part number of what to purchase. I'm just asking becasue I will have to get my AC working again one day. How bad is it really (not environmentally speaking) to vent it to the atmosphere?

[Steve N]

Thanks for the help everyone. Since I hate do things the wrong way I will try tightening it down some. If that does not work I will let a shop take care of the repair.

-Steve


Venting is bad- besides never open it without changing the dryer and never allow the drier to remain open to the atmosphere for long- it should be unsealed only immediately before fitting her in to the system. Do not open the system and then expect it to last if you let atmosphere or dirt enter and use it.

I'd tighten the connections 1mm or so (to move the thread) and take them up a bit to say what feels like around 50 ft/lbs, then clean and check for leaks a a day or two of use after that.

If you end up going into the shop, take a drier (new driers are $20 on eBay); most shops only charge for their time and the refridgerant they use... :) nick

[Dr. evil]

thier goes the o zone

[Bill R.]

When you have moisture or other contaminants in an a/c system, the refrigerant will react with moisture to form Hydrofluoric and hydrochloric acids which will attack various components of the compressor and usually cause copper plating failures within the compressor. The filter drier and or filter accumulator will help to prevent this. You don't want to just buy any cheapo filter drier replacement though since they are know to come apart and dump the dessicant in them throughout the system causing a real problem. The drying agent they use are bags of dessicant inside the drier just like you find in some items you buy that have that little white bag of dessicant in it to keep the items dry and moisture free... you know the one that says don't eat this bag.... Cameras sometimes come packed with them and many other pieces of electronics. At any rate you want a quality filter drier the same as you want a quality filter for the engine.



pulls moisture out of the compressed gases

[Anthony (M5 in Calgary)]

How bad is it really (not environmentally speaking) to vent it to the atmosphere?

Severe frost burns if you get the refrigerant on yourself...

[joshua43214]

cool. Can you show me a part number of what to purchase. I'm just asking becasue I will have to get my AC working again one day. How bad is it really (not environmentally speaking) to vent it to the atmosphere?

Umm well if you don't mind blasting all your refrigerant oil out, its just fine. Just make sure you add the proper amount of oil back in. of course you will have to make an educated geuse based on your experience as to how much oil to add.

AC service machines remove gas, not liquid. The small amount of oil that does come out, is separated and driped into a container so you can measure it and add the correct amount back in. the proper oil charge is as important or more important thanthe proper r12 charge. The AC system is far less tolerant of oil issues than an engine.

Also, as stated above, don't buy a crappy cheap reciever/dryer, the cheap ones fall apart clogging the expansion valve and then trash the valves in the compressor. This is not a part to skimp on.

[genphreak]

what is a drier?It removes moisture from the refirdgerant in the AC system. It is a cannister with silica and filter inside it. Once the silica is saturated with water you either change the silica or get a new dryer. Changing it is not practical so AC shops swap them out with new ones. At US$20 there is no point getting a quote on it here in Oz, so one just does it when gassing the system. From what Joshua wrote in his excellent thread (http://www.bimmer.info/forum/showthread.php?p=160769#post160769) your AC might just work with one of these and a re-gas. Of course it is better to try it sooner rather than later as your compressor might seize up if it remains 'dormant' for a long time.

Ps, Kris know sthis but for the benefit of anyone else that doesn't- the dryer is located on the RH side- forward of the front wheel under the washer bottle. It is a good idea to remove your washer bottle and anything else in the way before taking it to an AC shop so they can access it without spending hours tearing your car down or working out that the cold air intake trumpet slips out of the way (clean back into the air box) with a simple twist of a 'BMW experienced' hand. It is well in the way otherwise. :) Nick

[genphreak]

Umm... don't buy a crappy cheap reciever/dryer, the cheap ones fall apart clogging the expansion valve and then trash the valves in the compressor. This is not a part to skimp on.Any idea how to tell a good one form a bad one? I think mine was a German, perhaps Behr. Can't remember- but it wasn't an Asian copy. Is that good-enough?

Also, my compressor is noisy- the system lost its pressure naturally over some time and I then regassed- all is well for 5 months now, except for the compressor. Does that mean its got too much oil, is worn out or too little oil? Is there any way to tell? It is such a pity that AC is a PITA to work on oneself. The guys that did mine were pros, but I'd be happier of the compressor sounded like they do in a new car... cheers, Nick

[joshua43214]

When the system is low on charge or on oil, it will make a kind of zzZZZzz buzzing sound, like its normal running sound but louder. It will make a clunking or knocking sound when it is slugging an over charge of r12 or oil. They will also get louder over time as the valves get noisy.

the clutch bearings also fail and get louder over time, maybe normal sound for an old compressor.

[BillionPa]

Behr is OEM, good stuff, lasts for over 100K miles.