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E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 06-24-2015, 10:07 AM
DatRed318i DatRed318i is offline
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Mein Auto: 1996 BMW 318i (4dr w/ M44
Unhappy A/C Quit working and has very weird symptoms (1996 M44 318i)

Hi everyone!

So I have already looked through all the results of the search function for my problem but I've found nothing that matches up so far. I'll try to be descriptive as I can.

I bought a 1996 318i 4 door with a 5 speed back in February 2015 and couldn't have been happier! The previous owner stated that he had just gotten the AC compressor changed not too long ago at a reputable Independent BMW shop in Houston and it looked practically new so I gladly jumped on the car as soon as I saw it.

Fast Forward to May and the AC had quit working and every time the compressor would try to kick in the car would try to stall and struggle and the compressor would make grinding noises. So I took it to the same Indy shop that the previous owner had talked about and they stated that the previous owners son had actually gotten the cheapest compressor and used their floor space and some help from them to install it and that maybe the compressor was bad since the Aux fan wasn't kicking in and the Low-side would pressure upto 150+psig and the High-side was north of 500psig?!?!

They checked the wire to the Compressor clutch and it was good but the Aux Fan wasn't coming on either. They concluded that moisture had clogged up the Dryer unit so much that it wasn't letting anything flow through and the pressure sensor on the dryer wasn't seeing any flow and that was causing the sensor to not kick on the Aux Fan. So they changed the dryer out and voila! A/c worked like a charm!

HOWEVER, 2 days ago, the AC was working fine and I turned it off to speed up the on-ramp and when I tried to turn it back on once I was at a cruising speed, the AC quit working. I took it to the same Indy shop and they noticed that the center part (the Compressor Clutch) wasn't engaging. They didn't even bother to check the pressures this time and basically wrote off the compressor since you would hear the compressor pulley making a slight rattling noise with the AC OFF! (Remember this little detail.)

So when I got back home, I had one of those cheap Low-side Autozone gauges that you get to refill R-134 and found the following:

- Lowside pressure was at 150-160 psig (gauge only goes to 150psig)
- Outside ambient temperature was 90 degrees F (oh Houston)
- AC compressor clutch is getting power but center (the Mag Clutch) still does not rotate with the pulley
- AC compressor clutch make slight rattling noise when AC is OFF and I noticed that the clutch itself seems to wobble in and out (axially) when the AC/ Snowflake button is OFF.
- AC compressor clutch noise goes away when AC is turned ON but compressor Center (the clutch) still does not move. However, the wobbling axially of the clutch as well as the sound stops.
- With the AC ON and after revving the engine a bit, the sound comes back for a second or two but then goes away as the Mag clutch relay clicks again.
- I switched the low Aux fan relay and a/c clutch relay and same results


I was suspecting bad Compressor Mag Clutch bearings but HOW does the sound go away and not get worse when the AC is turned on? Mind you, the sound isn't really that loud and its not a whining sound. Just a tin-ny pebbles in a tin can sorta sound at idle and AC OFF.

I would GREATLY appreciate any help on this as I plan on DIY-ing it myself since the Indy shop wants $1,300 for the compressor ALONE!!!!

And about $1,800 when all is said and done. The 318i is barely worth that much! The Indy shop did say that they'll look into a cheaper but okay quality compressor but they haven't gotten back to me yet.

So is it the 1 year old compressor that just went OR is it just a faulty Mag Clutch?
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  #2  
Old 06-24-2015, 10:27 AM
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dc_wright dc_wright is online now
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With the AC off there's no magnetic field in the clutch so it's free to wobble as much as it can. When you turn the AC on the magnetic field is formed and trying to engage the clutch which is reducing it's freedom to wobble. That's my theory anyway.
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  #3  
Old 06-24-2015, 06:31 PM
DatRed318i DatRed318i is offline
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Mein Auto: 1996 BMW 318i (4dr w/ M44
Quote:
Originally Posted by dc_wright View Post
With the AC off there's no magnetic field in the clutch so it's free to wobble as much as it can. When you turn the AC on the magnetic field is formed and trying to engage the clutch which is reducing it's freedom to wobble. That's my theory anyway.
Thanks for the reply dc_wright! And yes, that does seem like a sound theory. Maybe the bearings on the clutch are shot and giving the Mag clutch enough clearance to not engage completely? Just an idea. It all just seems weird. I'm soo lost
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  #4  
Old 06-24-2015, 07:00 PM
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hornhospital hornhospital is offline
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If you're going to DIY it, you can get a new Denso compressor for about $350 with a 1 year warranty, or a rebuilt one with a "lifetime warranty" for $460. To have the warranty in force, you have to replace the dryer and the expansion valve, and the system must be flushed (you'll have to have proof of that with a warranty claim). Do you have equipment to do that, vacuum the new system, and charge it with R134a and PAG oil?
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  #5  
Old 06-24-2015, 07:16 PM
DatRed318i DatRed318i is offline
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Quote:
Originally Posted by hornhospital View Post
If you're going to DIY it, you can get a new Denso compressor for about $350 with a 1 year warranty, or a rebuilt one with a "lifetime warranty" for $460. To have the warranty in force, you have to replace the dryer and the expansion valve, and the system must be flushed (you'll have to have proof of that with a warranty claim). Do you have equipment to do that, vacuum the new system, and charge it with R134a and PAG oil?
I do not currently possess the equipment to vacuum the new system at the moment. I was planning to get the system depressurized by an AC shop, take the old compressor out, bolt all the new bits in and then get the system flushed and charged by said AC shop. would that be proof enough if a warranty is needed? Was actually planning on getting the whole kit from a RockAuto supplier called GPD for $180.

However, I was just hoping that maybe just replacing the Mag clutch (if that's the only problem causing the compressor to not work) without messing with the refrigerant would solve the problem. I currently do not have much money saved up if any.

So hornhospital, do you think that the compressor is far gone and needs to be replaced?
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  #6  
Old 06-24-2015, 07:27 PM
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I don't know how restrictive their warranty policy is. I have no way of knowing if your compressor is bad, or just the clutch. It really needs to be diagnosed by a pro shop. There are too many "what ifs" to say, yes buy a compressor, or no, just replace the clutch.

What kind of warranty does RockAuto offer on the GPD kit? That sounds way, way too cheap to be a set of good parts, but who knows, they may be fine.
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  #7  
Old 06-24-2015, 07:29 PM
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i'd suggest replacing the entire compressor assembly. quicker, easier, and better warranty. plus nothing sucks more than replacing the clutch and a few weeks later replace the rest of the compressor.

i'd also suggest resealing the system while it is empty. if you have a leak, keep in mind the rest of the seals are the same age (or thereabout).


btw, the low side should be about 30psi (cycling between 20-40 if not a constantly variable compressor design).



df
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  #8  
Old 06-24-2015, 07:32 PM
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Originally Posted by drivinfaster View Post
btw, the low side should be about 30psi (cycling between 20-40 if not a constantly variable compressor design).



df
That's what I though when I read the low side was 150ish PSI, like, jiminy, that's WAY too high.
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Quotes to live by:
guessing gets expensive...drivinfaster
nothing is more expensive than a cheap BMW...c4harpe13
buying a ratty example (of a BMW) is a parasitic relationship.(and you ain't the mosquito) 7pilot
Ken Kanne, Silverhill, AL, E36 Forum Mod/Craigslist addict/Hoarder of all sorts of stuff
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1995 318is "Bebe"; 1993 325is "Elvira"; 1985 635CSi "Katja"; 1984 633CSi "Sylvia"; 1987 325is "Odette"

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  #9  
Old 06-24-2015, 08:02 PM
DatRed318i DatRed318i is offline
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Mein Auto: 1996 BMW 318i (4dr w/ M44
Quote:
Originally Posted by hornhospital View Post
I don't know how restrictive their warranty policy is. I have no way of knowing if your compressor is bad, or just the clutch. It really needs to be diagnosed by a pro shop. There are too many "what ifs" to say, yes buy a compressor, or no, just replace the clutch.

What kind of warranty does RockAuto offer on the GPD kit? That sounds way, way too cheap to be a set of good parts, but who knows, they may be fine.
It appears that they offer a 1 year warranty somehow?! The compressor is only $140 or so odd dollars. That's HELLA CHEAP! Below is the link:

http://www.rockauto.com/catalog/more...nid=451&jpid=0

Do you have any specific questions that I could answer to narrow down the problem? I admit that maybe going in to a professional may be the only option. I have experience working on cars but I've honestly never messed with Air Conditioning before, besides the usual R-134 recharging from a can, lol
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Old 06-24-2015, 08:11 PM
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did you read this??

http://www.bimmerfest.com/forums/sho...d.php?t=611551




should help answer some questions.




df
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  #11  
Old 06-24-2015, 09:11 PM
DatRed318i DatRed318i is offline
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Quote:
Originally Posted by drivinfaster View Post
i'd suggest replacing the entire compressor assembly. quicker, easier, and better warranty. plus nothing sucks more than replacing the clutch and a few weeks later replace the rest of the compressor.

i'd also suggest resealing the system while it is empty. if you have a leak, keep in mind the rest of the seals are the same age (or thereabout).


btw, the low side should be about 30psi (cycling between 20-40 if not a constantly variable compressor design).



df
Maybe changing the entire compressor just might be simpler afterall ever since I found the more reasonably priced one on Rock Auto for $180 and get that installed by a pro AC shop. That sure will beat the Indy shop's $1,800+ bill!





Quote:
Originally Posted by drivinfaster View Post
did you read this??

http://www.bimmerfest.com/forums/sho...d.php?t=611551




should help answer some questions.




df
And daym! That sure is a detailed procedure. I just may do that this 4th of July weekend. Until then, I'll just have to suck up the Texas heat.
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