DIY: replace your A/C condenser, vacuum & re-charge

[atlantisvip]

Need to do this.. THANKS !

[edgarski]

Thanks mate. I dont know if my pals own a manifold but I'll check out auto shops this weekend.
Once again thanks for your tips. Appreciate it !

Cheers

It's true you may see the dye coming out from your leak point. The fact that its dark in there and the fact that most dyes are florescent makes the use of a black light even more informative.

I used a dye from kragen (auto parts store here in the US) once that left a powder residue even after a couple of months. That might be a hint for you.

Otherwise, take it to a professional to get it inspected. There are many points of failure, most common being the condenser followed by the compressor. A good way to test it is to have them evacuate the whole system (don't just let the refrigerant let go in the air) and pull vacuum to 29-30Hg for 10-15mins. Take the car home and wait a day. Go back and see if you still have about 29Hg. If you don't, you have a confirmed leak, and now the trick would be to find it. A dye test helps for those components in the engine compartment, but if your evap is leaking, that would be harder to diagnose (and replace since its behind the dash).

But it sounds like your cold air may be intermittent - maybe he didn't charge it enough? without knowing the pressures, its hard to diagnose. Post the pressures here (hi side and lo side) and I can try to help out. Just for reference, while the AC is running full blast, you should see about 180-220psi on the hi side and about 30-45psi on the low side. If you're hovering around 21psi on the low side, the compressor will kick on and off and hence you'll get that intermittent cooling feel. Generally an indication that your low on refrigerant. If you don't get the full 180-220psi on the hi side, generally means that your compressor may be shot, and is having a hard time compressing the gas.

Sorry for all the info, let me know how it goes.

[axroh]

No problem. please let me know what pressures you read - and I'll help diagnose from there.

[NHbmw325I]

awesome! My ac doesnt work on my car. I was told that the problem is mostly likely in the part that is located near the dash area.

[jarozila]

Great DIY axroh!!

What's the go with the cricket bat?? Not something I would expect to see used as a prop from someone in the US.

[Henry602]

I experience same problem with my E30. Please anyone ready to help give useful suggestions?

Hi everyone, i have 2 questions:

is it true when you have too much pressure the compressor will cycle on and off frequently? just had the car serviced in a brazilian dealer and have notticed this ever since it returned but they say it is normal.

on really hot days (100F) the a/c is not cold enough on traffic eventhough it get much better on highway and it works wonderfully at night... could a bad heater valve be the problem? it is a 12 year old E36 and i have never replaced that...

[axroh]

A common problem that I hear is "my AC works better when I drive, but not at idle" - is generally related to impending compressor failure or not enough pressure in the system. The compressor is belt-driven, and sometimes only when the car is running on the freeway does it generate enough compression (due to speed) to achieve effective cooling. It is also possible that pressures are too low, and the compressor clutch will engage-disengage frequently; also giving the effect of "not so cold air".

Without knowing the pressures (hi and lo side) and ambient air temperature outside, it may be hard to diagnose. If you can supply that information I may be able to pinpoint it better.

btw, regarding the cricket bat: I use to play with a bunch of friends aeons ago in college - so I bought one.

[x2nervisx]

Sorry to bring up an old topic but I replaced my condenser, dryer and orings changed last summer but i never had my a/c system recharged since I didn't have time and it was the end of the summer. However this summer I'd like to finally recharge the system and I was wondering since I don't have a vacuum pump or access to one, is it alright if I just recharge the system myself with those recharging kits that already have lube in the recharging can? Basically can I skip the vacuum and oil step and just recharge the system?


If it is alright to recharge without the vacuum and oil, I see in the recharge kit that it tells me to keep the engine running and have the a/c system on max settings while recharging. However since there is no refidgerant currently in the system, i read that the a/c system won't work since the compressor won't turn on since it doesn't detect any pressure in the system. So do I recharge it anyway till the compressor kicks on?

[axroh]

You will have to use a vacuum pump unfortunately. For two reasons:
1. running a vacuum at 30Hg for 2-3 hours evacuates air in the system
2. the boiling point of water drops dramatically down (to less than 50deg) under vacuum. This is important, since you don't want any moisture in the system.

That being said, you may already have a problem. If you didn't vacuum your system last year when you replaced those parts, you may have corroded some components. You basically have a sealed system with moisture inside with no way for it to evaporate. My fear would be the compressor bearings, or more importantly your expansion valve may have gotten jammed.

If you chose to re-charge without running a vacuum, it will not last long. moisture is a bad thing in an AC system. Not to mention, water is not as compressable as R-134a, which means your cooling will be less than adequate.

Regarding the compressor kicking in, I think the denso compressors for the E36 engage the clutch at about 25 psi on the low side. Anything lower than that won't kick on the clutch.

g'luck.

[pedro05]

I have managed to buy the pressure reader... last time the dealer said it just needed some more gas...

it reads around 40/47 on the low side and 190+ on the high.

i then took the car to the shop and asked the cheif of staff if the problem was due to excess of charging and he told me there is no such thing, the compressor is just failing to compress the low and this reflects the high pressure also.

can this be true?

A common problem that I hear is "my AC works better when I drive, but not at idle" - is generally related to impending compressor failure or not enough pressure in the system. The compressor is belt-driven, and sometimes only when the car is running on the freeway does it generate enough compression (due to speed) to achieve effective cooling. It is also possible that pressures are too low, and the compressor clutch will engage-disengage frequently; also giving the effect of "not so cold air".

Without knowing the pressures (hi and lo side) and ambient air temperature outside, it may be hard to diagnose. If you can supply that information I may be able to pinpoint it better.

btw, regarding the cricket bat: I use to play with a bunch of friends aeons ago in college - so I bought one.

[pedro05]

and one other thing, the BMW dealer said they only vacum systems for around 30 minutes or so, should i be looking at buying a vacum pump for myself also???

[axroh]

With the system running, 40-47 is ok on the low side. It could be lower, but that's fine. The high side could be a bit higher, perhaps 210 or so, but 190 is ok.

And yes, you can overcharge a system. The guy at the $tealer you spoke to does not know what he's talking about. I don't have my system capacity chart with me for the E36 - but I think its 45oz R-134a, 8-10oz PAG45 oil. If you overfill, your cooling capacity will be affected.

Is your call not cooling? Can you verify that the clutch is engaging on the compressor?

[pedro05]

clutch is working just fine... the thing is, when i turn on the A/C it does not turn on instantly.

it takes a while, like 2/3 minutes to engange and it stays afterwords.

the $tealer said the reason it is taking a bit longer to engange is due to a eletrical malfunction inside the compressor and there is no way to repair it... i think it is a whild guess.

yesterday i heard a popping noise at idle, other than that, it is woking just fine.

only when outside temp reaches 33F that it starts to fail in cooling at idle
YIKES!

[axroh]

Its possible that your expansion valve is sticking. When the compressor starts generating enough pressure (after 2-3 minutes) it may be opening just enough for R134a to start flowing. That would explain why its not cooling as effectively as well.

AC diagnosis is hard. There are quite a few parts to the system not to mention a certain amount of experience is required to diagnose. The parts ain't cheap either.

Let me know if there's something else I can try to help out with. If you're feeling rich someday, you can try buying a reman. compressor on ebay for roughly $250 US.

[x2nervisx]

Do you know what kind of oil was used for the a/c system? There a few different kinds and Im not sure which to get.

[axroh]

I'm out of town right now, but I think its PAG45.

[Bearcat77070]

I had my compressor lock up on me, I had to cut the belt off of it to be able to start the car. I have a remanufactured compressor, new receiver drier, and new expansion valve. Would it be a good idea to blow out the lines while I have the system apart in case when the compressor failed some part of it made it's way into the lines and might cause problems? If I did blow the lines out, could I use canned air like what's used for computer applications (shouldn't be introducing moisture this way I figure, unlike air from a compressor) or can I use a can of R134a somehow? Or just not bother with it?

[axroh]

Most people will tell you that you should blow out stuff from your lines especially if your compressor locked up because of debris. Because of the direction of refrig. flow, it really can't make it past the receiver/drier. So, the real thing you need to flush is your condenser.

Here's a link that will explain the different solvents:
http://www.e38.org/pparish/flushing.htm

You can also talk to the smart folks at ackits.com. Those folks carry a bunch of flushing stuff too.

A thorough amount of work would require flushing each component individually, which is time consuming and may not be worth it considering the age of a vehicle. The problem is that if there's debris after the expansion valve, it will make its way back to the compressor and bad things could happen again. Similarly, debris after the receiver/drier can block the small orifice in the expansion valve.

When I did my car, I just flushed the AC condenser with air (using a compressor) and then some stuff I bought at ackits.com. I think it was some mineral spirits. My AC has been working ok now for 3 years. It's not as cold as my 94 maxima's AC, but for the amount of time I spent on a 14yr old car, I'm real happy. My mantra is 'pick your battles'.

Hope this helps

[SixAfterFour]

Just puncutred my condensor, sigh.

Is there a difference between models? i have a 95 318ti? could i grab one off say a 97 325?

And could somone quickly explain to me the manifold? im assuming you have to make your own.

[jeffro0502]

I just bought a new condenser, all the research I did indicated same condenser on all the E36 models. I got mine just tonight off of Ebay for $120.00 with free shipping. Should be in here in about 4 days. I'll post on the quality of it when I receive it. I had found a goopy mess coming out of the drain pan that I had thought to be seeping radiator but the level never did go down for the coolant. I crawled under pealed the pan back and found crudy mess on the bottom of the condenser with a wax like paste coming from a small spot on the condenser, I'm guessing that was the AC stop leak stuff it was green like the green dye and real oily. I'm hoping the new condenser fixes the issue.

[vull]

signing up

[evilbean]

I'm going to pray for a job well done on this one as I've never done AC work.. In fact, I've never even had a car with AC.

I just bought a Condenser, Fan Shroud, Auxiliary Fan, Condenser Brace, and Brand new Receiver/Drier off eBay for 205.49 shipped.

Now I need to buy my gaskets, refrigerant & oil...

Hopefully I can find someone with a vacuum pump and manifold. I've been reading these directions all week. Anything else you can tell me about the process? I don't have a splash guard that sits under the condenser. Do I need to get that too?

[stixoffire]

"My car had no pressure in it, so this step didn’t apply to me. "

0 Pressure is not 29hg of Vacuum - the step always applies - the system must be at a vacuum!

[Grasshopper2Ant]

Hello guys, I have a 1991 325i. Car blows warm. Compressor clutch comes on normally.

I have 30 psi on LOW side without engine running. Is this normal? I put in a can of red dye to check for leaks but cannot see anything with UV in all parts. Did not check part (evaporator ?) in passenger dash as it looks like a bitch to access.

Can someone steer me through to help troubleshoot my problem and how to fix, thanks for any assistance.

[choffa]

Pressure must be checked with it running. The pressure you're reading is called the settle out pressure, doesn't correlate to operation, only system capacity.

An electronic sniffer is the best tool, $$$ might be able to rent one. To look for an evaporator leak with the dye, check the water dripping from the evaporator drain (passenger side firewall). Check pressure with system running, after the low side pressure settles down (comopressor running for 30 seconds or so). Remember too much refrigerant is as bad as too little. Low side pressure should be in the range of 30-40 psi running.