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A/C pressure sensor switch question.. and other various things

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  #1  
Old 10-28-2008 | 08:28 PM
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A/C pressure sensor switch question.. and other various things

so... a couple of weeks ago i turned my a/c on and it started to get cold, then all of a sudden went hot. the air still blows out of it. I've been trying to diagnose the problem and have spent quite a bit of time looking around on the internet on various sites... i did find one like bmw-oem site that had diagrams of all of the mini's systems... it hasn't been much of an issue, cause the weather's been so nice here lately.. until it rained the other morning and I couldn't see out the window on the way to work due to the condensation on the windshield.. of course it's 6am, dark, and everyone's doing 80 bumper to bumper on I-75...

anyway.. I'm under the impression that the A/c Clutch isn't available w/out buying the whole compressor. bummer. I DID manage to find a guy here in tampa that told me he could (and has in the past) rebuild the clutch in it for $129 (providing i bring it in to him and he doesn't have to take it off).. not bad (like less than 1/2 the price of the whole compressor anywhere i could find it on the internet.)

it looks like the high-side pressure sensor is under the air box, am I right? is it hard to get to? I want to try to jump around the sensor with a paperclip or something during my lunch to see if it's the sensor that's bad before i spring for the clutch rebuild. anyone know what sized sockets or if it's a screw-driver job to get the airbox off? and whether or not there's one of those schrader valves behind the sensor so that i don't have to drain the system to get it out when the new one comes? (which another shop told me he'd charge $85 to empty it and refill after i work on it.... I KNEW I was in trouble there when he asked me what kind of car it was and who made it.. eek.)


also.... I've got a couple other issues and I haven't seen any answers in all of the posts that I've read.. I have seen people talking about issues with their minis kinda feeling like they're going to stall out shortly after starting them and driving a short way, but mine stalls out after I've been riding out for a while and take it out of gear and come to a stop like if i'm gonna turn left in a turning lane, or getting off the interstate. i've had it actually stall out a couple of times as I've slowed to turn left through a break in traffic but had been moving quick enough still to make it through the intersection and sort of "push start it" as I move out of the intersection... (full tank of gas or not, and more often when i'm slow-poking around than really getting on it) any ideas? (note that i haven't noticed this happening recently, since the a/c hasn't been working.)

possibly related to that... i've noticed that when i'm sitting idling at a light or in traffic (again, not at all now recently though since the a/c has been off) that when the radiator fan turns on it makes the RPMs drop off almost to nothing. again, like it's going to stall. but then they kick back up and it idles fine after that. but it cycles all the time, and it's LOUD as all hell.

oh... btw... she's an '03 MC with.. wait for it... wait for it... 80k miles this week... (ought to turn it over thursday or friday..)

I plan on taking some pics as I go along on this one and I'll post them up here for you all...
 
  #2  
Old 10-30-2008 | 02:05 PM
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From: Hotlanta
Replacing Safety Pressure Switch

Discharge air conditioning system.

R50 only:
Remove battery box.

R53 only:
Remove intake air filter housing.



Disconnect connector (1).
Remove safety pressure switch (2).
Tightening torque 10 Nm .
 
  #3  
Old 10-31-2008 | 11:15 AM
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thanks.

what do you think about my "bypass the sensor to see if it's the problem" idea??
 
  #4  
Old 10-31-2008 | 02:14 PM
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i would test the power and then go from there.

turn the car on....a/c ON and test power in then power out. if that comes up good then you should look at the compressor clutch if its engauging. for that you might want someone in the car turning the system on/off while you listen for the clutch engaugment. after that id need the car for further testing.
 

Last edited by 1FSTMINI; 10-31-2008 at 02:20 PM.
  #5  
Old 10-31-2008 | 02:56 PM
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k-huevo
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From: Pipe Creek, Texas
If you recover and recharge the system, replace the dryer before recharging; at $186 list it's not cheap. New gasket rings will be needed if you pull the compressor.
 
  #6  
Old 10-31-2008 | 02:58 PM
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why would you replace the receiver/dryer for a recover. thats only need if the system failed and sent metal throughout.
 
  #7  
Old 10-31-2008 | 04:28 PM
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k-huevo
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From: Pipe Creek, Texas
There are more reasons to replace the dryer than debris in the system. Two situations that may apply here: the system is open more than 24hrs (compressor removal), the dryer has been in service more than 2yrs. A humid environment such as Tampa adds a Z factor.
 
  #8  
Old 11-01-2008 | 07:02 PM
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not to mention that she more than likely was in Miami before we bought her.
 
  #9  
Old 01-14-2009 | 05:10 PM
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hey. hi. it's been forever and a day, i know.. but i'm just this moment getting down to business.. the weather's been nice here in tampa and i haven't even missed it once since it went down. but every dog's got his day, ya know.

anyway.. here's what's transpired since my last post:

1) i found a guy here in tampa that said he would rebuild the clutch in it for like $130. that's less than half of the cheapest price i could find for the whole compressor, and he said that he's done one before. (ace auto air, tampa, 813-243-5306; if anyone's interested)

2) other people have confirmed the whole "if it's open that long you've got to change the dryer" thing.. and (provided that's the problem) i'll be tearing her apart this weekend, having the compressor rebuilt during this week, and won't be be able to put her back together until next weekend most likely.

3) i made an appt with a guy near my office for tomorrow @ lunch to have him drain the refrigerant. he'll refill it once i've put it back together. ($85)

4) I ordered the drier from thepartsbin.com ($91.95) it came in today.. i guess if i decide i'm replacing the sensor in lieu of the clutch i can return it and have them send the sensor along with the refund.. which all prompted me to

5) FINALLY get off my back-side and take the battery box off so that i can test that sensor (which is how she sits in my garage while i write this).. and right now i'm scratching my head trying to decide how to go about this.. (this was no obvious task by the way.. I'll take a few pics and post some tips about that part later on..)

i'm searching for that thread that had some pics of that sensor (please point me to it, if you know how to find it).. i want to make sure i'm f-ing with the right one. there looks like there's more than one under that battery.. only one looks like it's in an a/c line though.

by the way. i also bought two new O2 sensors from thepartsbin.com, too.. they were only $55 or so for the pair of them. granted they don't have the wiring harness and i'll have to splice them to the one from the oem part, but that's like only 25% of what the others would have cost.. i'm doing that this weekend, too (along with some EBC front brake pads).. pics to come.

peace.

me
 

Last edited by ghurm001; 01-14-2009 at 05:33 PM. Reason: accidentally posted before i was done writing
  #10  
Old 01-15-2009 | 06:25 AM
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SO ANY UPDATES?? Did you figure out what was going on?
 
  #11  
Old 01-20-2009 | 08:35 AM
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[quote=ghurm001;2529856]so...
when the radiator fan turns on it makes the RPMs drop off almost to nothing. again, like it's going to stall. but then they kick back up and it idles fine after that. but it cycles all the time, and it's LOUD as all hell.






I hope this get to you in time.... The problem with your car is "No low speed on the radiator fan"

This is why when the fan comes on the engine almost dies...it takes a lot of juice from the charging system to run in high speed and the engine will shake for a second when this happens.

The low speed series resistor is most likely open. This resistor is located on the radiator fan shroud (high wattage wire wound resistor).

This is why the fan is loud and the A/C blows warm or hot.

The low speed should engage at 105c and turn off at 101c.

High speed should only engage if the coolant temp gets to 112c (which is what is happening in your case)...the PS fan also runs at this temp.

You need to replace the radiator fan assembly and your troubles will be gone.

FYI...you can use an OBD scan tool to monitor the ECT parameter when the fan comes on; you will find the value is 112c.
 
  #12  
Old 02-09-2010 | 06:57 PM
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long overdue update

It's done. has been for a while.. anyway.. the dryer, cake to replace.. the compressor, not so bad either. all in all it took me longer to clean out the garage enough that i could fit her in there to do the work than the actual work to fix the problems did. I highly recommend the a/c guy i listed in my previous post. They had the work done overnight and had the O-rings for me for $1 a piece when the dealership wanted like $35 for the set.

Notes on the project:

1) even though the a/c lines are drained.. there's still pressure in the line at the compressor. small surprise, watch your head.

2) I didn't have the 100mm bolts that i've seen referenced on some writeups that i suppose are used to put the radiator into "service mode." instead i just took the top hose off the radiator and leaned it out some. I got to the bolts on the compressor from the top and then just forced the compressor out through the bottom. It took a little pulling and contorting, and my father-in-law to pull the radiator some, but it really wasn't all that bad.

3) next time, god forbid, I'll get some replacements for the body clip things that hold the wheel wells and fenders all together.

4) i (and you, probably) need to get a belt tensioner lever tool thing, that belt was a real pain without one.

there was a good walk through that i found here on NAM, but i can't remember who posted it, but if i run across it again later i'll link to it from here. There were a bunch of good pictures on it though.

only lingering issue with it: Now, when the a/c is on, and my RPMs are decreasing through 1400/1300, i get a funny kind of groan that sounds like it might be the belt, but it only happens for a moment and i don't notice any change in the idle or the lights or anything.. i suppose it wouldn't be a bad idea to get a new one, i do have over 112k miles now.. did i mention i'm STILL on the factory run-flats? 112k miles on the same tires? who else can say that? not for long, though, they've seen better days.

As far as the O2 sensors issue goes..

I replaced both of them that same day and brought it to advance auto to get the check engine light reset. turns off, but after driving a bit it comes back on.. pepboy's check engine light thing is more informative and told me that it was a problem with O2 bank 1 (nearer to the engine). so, either the sensor they sent me was bad, or the wire that i connected it to is shorted out somewhere up the line.. either way I don't know yet just because i haven't bothered. Huh? what engine light?

but.. all of that is going to have to wait for now.. i had the wonderful experience of my clutch giving up on me today.. in tampa rush hour traffic.. so, now i've got a new project. :-\ (by the way, that was NOTHING like the clutch going out on my VW golf that i had.. that took moths of slipping before i sold it.. the mini never slipped, it just started making a(n intermittent) grinding noise while i depressed the clutch pedal this morning. i drove it maybe a total of 4 miles from the time i noticed it before it gave up.)

wish me luck. again.
 
  #13  
Old 02-09-2010 | 08:04 PM
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Good to hear you got the ac working, sorry to hear about the clutch. When you do the clutch...replace the radiator fan... As previously noted the low speed portion of it has failed. Aftermarket ones are about $100 from rock auto and e-bay. There are several threads, and you have decribed the symtoms to a tee...a few folks have also lost ac compressors too!!
 
  #14  
Old 02-10-2010 | 02:43 PM
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Very good info in this thread! So, if swapping out the compressor for a known good one, the only other maintenance parts needed are new o-rings for the lines at the compressor (I'm assuming 2), and the dryer?

Originally Posted by ghurm001
there was a good walk through that i found here on NAM, but i can't remember who posted it, but if i run across it again later i'll link to it from here. There were a bunch of good pictures on it though.
Also, if you can find the walk-thru you used, and post it up, that would be GREAT!
 
  #15  
Old 02-14-2010 | 01:22 PM
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Originally Posted by shorty_du_op
Very good info in this thread! So, if swapping out the compressor for a known good one, the only other maintenance parts needed are new o-rings for the lines at the compressor (I'm assuming 2), and the dryer?



Also, if you can find the walk-thru you used, and post it up, that would be GREAT!
pretty much just the o-rings. i replaced the dryer because i had to have the system open for so long. i took it all apart over the weekend, brought it for the rebuild on monday, picked it up tuesday and had it back together tuesday night. Even though i used some saran wrap and rubber bands to seal off the a/c lines while they were open i wanted to make sure that i wasn't going to have any issues with moisture in the lines. so i changed the dryer. I'm under the impression, though, that if you've got a good one that you're going to put right back in as soon as the old one comes out that you might ot have to replace the dryer.. but your system's already discharged and open so why not?

as for the walk through, i'm thinking i may have found it off NAM, but through a link on here somewhere... i'll keep looking..
 
  #16  
Old 02-14-2010 | 02:21 PM
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From: Temecula, CA
Is this the one?
http://www.lonestarminiclub.com/foru...=4179#post4179

I'm working on putting together a DIY AC troubleshooting and replacement thread, so am trying to coral as much info as I can. I also have both Bentley manuals coming in this week which should help.
 
  #17  
Old 02-15-2010 | 10:41 AM
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Originally Posted by shorty_du_op
YES! that's it! Fantastic write up there... the only thing that i didn't do that's in it was the expansion valve..
 
  #18  
Old 08-31-2010 | 11:17 PM
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Originally Posted by 1FSTMINI
i would test the power and then go from there.

turn the car on....a/c ON and test power in then power out. if that comes up good then you should look at the compressor clutch if its engauging. for that you might want someone in the car turning the system on/off while you listen for the clutch engaugment. after that id need the car for further testing.
I have a 2003 Mini Cooper S and my A/C had recently died. I had the same symptoms that "ghurm001" had. I took my Mini to a JPR Automotive and the tech said that the freon was low by approx 8oz. He topped it off along with a dye to check for leaks. He went to power up the compressor, but it didn't turn on. He tested for power going to the compressor and confirmed that was working fine. He is suggesting that the compressor is bad.

I just wanted to confirm his recommendation with a 2nd opinion? Please let me know what you think?
 
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