Air conditioning refresh

[toy4to]

Funnily enough, i was watching the last video about front end removal yesterday 👍

Yes that last video is useful for accessing the condenser. My condenser fins are all disintegrating. I haven't had working AC in my car for probably 6 years now. Have to stop the insanity and do this job this winter.

[ac427]

Yes that last video is useful for accessing the condenser. My condenser fins are all disintegrating. I haven't had working AC in my car for probably 6 years now. Have to stop the insanity and do this job this winter.

This is a good video for A/C diagnosis - https://www.youtube.com/watch?v=9j9MgxNwZxI

[Nate047]

Been dreading and delaying this, my car had a problem
where at first, the AC stopped blowing cold on the passenger side but was still cold on the drivers side(?) but now it’s not really cold on either side anymore. I haven’t diagnosed or done anything because my car is a basket case with lots of other issues that are more pressing.

[ac427]

I'm thinking of investing in some manifold gauges and dye to try to find the leak before i start replacing things.

One of the videos i watched about A/C mentioned 50ml as a BMW specified minimum quantity of oil for the compressor.

[Black107]

I did this a couple years ago after suffering with my car not blowing cold for a while (and the compressor whining), it has worked great ever since I did all this, some notes:

• I took it to an indy shop to have them pressurize it and see if it had leaks. They reported that it was leaking from most of the seals so they evacuated it and I went home and started shopping for parts to DIY.
• I ended up reusing all of my lines, just with new o-rings.
• New Nissens condenser which seemed high quality except it seemed like the connector got slightly tweaked in shipping so had to sort of tweak/bend it back to mate up nicely when installed.
• New (might be a reman?) Denso compressor, original one on my car (02) was also marked Denso.
• New Mahle Behr Receiver Dryer and Expansion Valve (EV that came off the car was marked Engelhof), A/C Pressure switch, schrader valves/filler ports
• Bought PAG46 oil and it was definitely an adventure trying to figure out how much to put in esp considering I replaced the condenser. My notes say I was shooting for ~5.2oz and ended up with a little less than that, maybe 4.5.
• Used a manifold set I bought from Harbor Freight (the second one, as the first one was defective and didn't hold pressure 🤦♂️), this was pretty straight forward if you watch some of the videos on youtube. If you take your time it's not hard to get the spec 740g +/-25 in the car.
• Holy shit does it suck trying to screw the expansion valve in. There's a plate that sits behind the flanged part of the two lines in the dash that you need to screw two bolts through the expansion valve through and into this plate. The plate has nothing to rest on so it falls away from you as you try to screw in the bolts. Compounding the issue is there's very little room in this area because of the cowl. I ended up finally rigging some zip ties behind it after much trial and error to try to pull it forward as I was trying to screw in the bolts and they finally caught.
• Pay VERY close attention to the whereabouts of the yellow plastic gaskets/bushings that are on the ends of the AC lines as you're removing and reinstalling the lines. Several popped off during removal and reinstallation and I lost one only to discover that they are not sold individually so I had to buy one whole new line, only to later find the one I lost after the car was all back together. They also seemed easy to mangle, so make sure the AC lines are seated perfectly before bolting them down.
• I took the right front wheel well panel off to get better access to the dryer (kept bumper on).
• Get new hardware for the AC line connections and expansion valve if you're replacing it. My car has lived in SoCal its whole life but there was a fair amount of corrosion on some of the hardware, especially those on the compressor.

Unfortunately there aren't a ton of detailed writeups or videos for this diy, the series from 50sKid on youtube was probably the most helpful but I think I pieced together info from several videos.

[ac427]

Black107 Thank you for the detailed information. Just a couple of questions if you wouldn't mind:

Did you remove the from bumper to replace the condenser?

Was your evaporator ok?

Are there any known pressure figures to check for on the high and low side on a working A/C system?

Did you pressure test your system before refilling?

[Black107]

Did you remove the from bumper to replace the condenser?

Nope, left the bumper on. I was planning on doing a coolant flush anyway so wasn't big deal to remove the rad and hoses.

Was your evaporator ok?

IIRC the indie shop said the expansion valve+evaporator+cowl area was the one area that wasn't leaking (probably because the o-rings have the most protection from heat) but I did the expansion valve and its o-rings anyway so the entire loop would have new rings. Plus, replacing the evaporator is a MUCH more involved job so I was crossing my fingers that doing rings, compressor, condenser, dryer, EV, and switch would be enough (so far, 2yrs later, seems it was).

Are there any known pressure figures to check for on the high and low side on a working A/C system? Did you pressure test your system before refilling?

So if you're asking about refrigerant yes, you're supposed to get a certain about of refrigerant into the system by weight. In terms of "can the system hold pressure", the DIYs I watched recommended pulling a vacuum on the system after you put everything back together and seeing if it holds overnight. Mine did, so I proceeded. I can't remember if I also pressurized it to see if that held, but I may have just said "new o rings holding vacuum is gonna have to be good enough for me" cause I don't have an air compressor, just a tire inflator.

To be honest, after buttoning everything back up is probably where I could have gone back to the indy and had them pressure test, oil, and recharge the system and probably come out about even with buying oil, refrigerant, manifold, vacuum pump, etc, but it all worked out in the end. Allegedly some of the parts stores have manifolds to borrow but I was worried about a precise tool like that being banged/imprecise up as a rental.

One other thing -- I got these spray cans of AC line cleaner to clear out all of the old oil from the lines to prep for the new oil. This was largely because I replaced the compressor and especially condenser which meant I then had no idea how much oil would be left in the system if I didn't clean it out. The indy shop tool usually can fill/drain the refrigerant and oil at the same time, and they drained mine, but again this system hadn't been touched in 20+ years so figured why not be thorough.

[ac427]

Nope, left the bumper on. I was planning on doing a coolant flush anyway so wasn't big deal to remove the rad and hoses.


IIRC the indie shop said the expansion valve+evaporator+cowl area was the one area that wasn't leaking (probably because the o-rings have the most protection from heat) but I did the expansion valve and its o-rings anyway so the entire loop would have new rings. Plus, replacing the evaporator is a MUCH more involved job so I was crossing my fingers that doing rings, compressor, condenser, dryer, EV, and switch would be enough (so far, 2yrs later, seems it was).


So if you're asking about refrigerant yes, you're supposed to get a certain about of refrigerant into the system by weight. In terms of "can the system hold pressure", the DIYs I watched recommended pulling a vacuum on the system after you put everything back together and seeing if it holds overnight. Mine did, so I proceeded. I can't remember if I also pressurized it to see if that held, but I may have just said "new o rings holding vacuum is gonna have to be good enough for me" cause I don't have an air compressor, just a tire inflator.

To be honest, after buttoning everything back up is probably where I could have gone back to the indy and had them pressure test, oil, and recharge the system and probably come out about even with buying oil, refrigerant, manifold, vacuum pump, etc, but it all worked out in the end. Allegedly some of the parts stores have manifolds to borrow but I was worried about a precise tool like that being banged/imprecise up as a rental.

One other thing -- I got these spray cans of AC line cleaner to clear out all of the old oil from the lines to prep for the new oil. This was largely because I replaced the compressor and especially condenser which meant I then had no idea how much oil would be left in the system if I didn't clean it out. The indy shop tool usually can fill/drain the refrigerant and oil at the same time, and they drained mine, but again this system hadn't been touched in 20+ years so figured why not be thorough.

Thank you again for the great detail.

I went to the Indy for a diag session. He put the manifold on and there was pressure in the system. The compressor was working too. He couldn't find any even though dye had been put in the system previously. I should have asked him to do the pressure test but he seemed to be a bit of a difficult bugger.

He did say he has seen the two lines that run down near the exhaust cause issues in the past on E46's. He couldn't see leaks but could not see because of the foil effective heat shielding. I thought i would just buy those two hoses new from BMW. Well until i saw the price i did.

He had a traditional gauge manifold set up and also a digital one. I managed to get a Robinair vacuum pump after dealing with some dreamers on eBay. All the pumps look more or less the same but vary in flow rate. I managed to get the 10CFM model. I didn't realise it weighs 22kg!

Can you remember which A/C line cleaner product you used?

[Black107]

I used AC Pro flush from Advance Auto. It’s just a solvent, i don’t think the exact brand matters much.

[ac427]

I used AC Pro flush from Advance Auto. It’s just a solvent, i don’t think the exact brand matters much.

Thanks. I wasn't sure. There was a suggestion of white vinegar.

[dukeofchen]

A guy on cutters replaced his condenser at 140k miles and said his radiator was mint because it is shielded by the condenser. The fins on the current radiator are supposed to be a softer metal according to some.

I'll probably leave the radiator alone unless it looks damaged.

Very interesting, and that makes sense. I wonder if we've been failing to fully consider what is literally a second radiator sitting right in front of the engine's radiator when we default to throwing new OE radiators and fan clutches at cooling issues. Especially since "my car is running hot" almost always comes with "it's worse when the A/C is on".

I mean the condenser takes not only the brunt of road debris, but also all the nasty stuff that flies in when it's wet out (I don't know how much this matters). On cars as low as ours, many with high miles, that adds up to hundreds of bent fins, corroded aluminum, and inefficient heat rejection when the A/C is on. Add to that an aged radiator, and you have less airflow, excessively preheated, requiring the A/C compressor to work overtime and drag on the engine (especially when sitting still). I don't see why this couldn't play a big role in the overall picture.

Hell, even if the A/C is off, bent fins would restrict airflow in both directions. Would this not then mean that we'd see airflow stagnation, especially in the case of clutch fans that aren't direct mounted, subsequently increasing flow diversion in every other direction than through the radiator?

🤔

[ac427]

Same for the oil cooler too.