I had a compressor blow out i.e. the over pressure plug on the compressor blew open and dumped the oil and freon all over the road in stopped 105 degree traffic and burned up the A/C clutch. So I replaced with new (not used) parts: the compressor & clutch, the expansion valve (what a pain), the condenser with dryer, the schrader valves. Flushed all the lines and evaporator with FJC AC flush. Put in 4.5 oz of PAG into the compressor (drained it dry first), all new seals and the vacuum held steady for multiple hours. Put in 14.5 oz of R134A and was rewarded with 60+F air and these gauge readings. To the non-expert (me) the low looks really low and the high looks OK (95 F day) but I am an A/C novice.

Anything (everything) weird about the Mini IHKA A/C system that would be causing this or do I start all over because the expansion valve would be suspect again? I checked the function of the heater door actuator (works), the level door actuator (works), and the recirculation actuator (works).

 

Anyone, now that the temp outside is less than 90F?

 

Just did some ac work myself.

new condenser / dryer and new compressor. With new o-rings. It held vacuum over night so I charged it.

air was nice and cold.

week later and no more cold air. So I have a leak somewhere.

While it was working right after charge...low presure side was higher than what ur seeing. It would build pressure on the low side up to about 50psi or so while the compressor was going. Then the comp. would shut off and the fan would come on and the pressure would drop.

again and again...

I think that’s how it should work. Or I should say the air was coooooold when it was working that way.

What compressor did you get?

some of them come w oil already in them. And I’ve read that 3 oz is the max you should add. Maybe too much oil?

im no ac expert. Maybe someone here can offer more

 

On a proper running A/C system, the low side pressure decreases while the compressor clutch is engaged (compressor running) and increases when the clutch is disengaged.

I normally see low side pressures around 30 psi when the clutch disengages and around 45 - 50 psi when it comes back on.

I think those gauge readings are too low on the low side and too high on the high side. To me, it indicates a restriction in the system.

Perhaps whatever caused the original compressor to overpressurize and blow itself up remains in the system? I wonder about all that added oil too. I've replaced many, many A/C compressors and the only time I ever needed to add oil to a compressor was when I replaced the secondary compressor on an ambulance. That system held 6 lbs of refrigerant though.

 

Thanks Ghostwrench and I agree about the low/high pressure readings, hence my request for help. I tried to ensure there was no oil in the compressor by rotating the pistons then draining again and again to make sure. The 4.5 oz of oil I got off of the web so that might be wrong and would appreciate correction if so. Can the system be flushed and back flushed again (removing the condenser and compressor) with the expansion valve still installed? That thing was a royal pain to remove and install. But if I do I guess it would push all the crap through it, probably not good. As to what caused the blowout to begin with, I assumed the expansion valve got stuck somehow. I have all the old parts and can do a postmortem if there is something to look for.

 

I don't think you're at the point to open up the system again.

I wonder if your evaporator temperature sensor is reading correctly? If it were reading incorrectly, it could allow your evaporator to freeze and that would cause a restriction in your system.

I'm not sure what vent temperatures a good functioning Mini system will give. I made a thread a few months ago asking that question because my Mini blows around 60 degrees, which when it's 115 degrees here is OK but the cars I work on (Ford and Volvo mostly) blow in the 40's and low 50's. I haven't put a thermometer in my vents lately, now that we've cooled into the 90's when I'm driving home. I haven't had gauges on my Mini in a long time either, so I have no way to compare your readings to the readings to those from my R53.

Does your car always blow 60's or does it start a little cooler than slowly increase? How about the pressures?

Another curious thing is if your system did reach such high pressure to blow up your compressor, how did a high pressure sensor not shut the compressor off before the pressure got too high?

 

Interesting questions with equally interesting (or dumb) answers...
Not sure about the evaporator temp sensor. Where is it and how would one test it?
The system blows cold for a few seconds... then warm for a few minutes... then cold for a few seconds... etc. which sounds like it might be freezing as you mentioned... could be getting close to an answer. As an empirical data point, my R56 blows COLD on 100+ days.
The pressures go quite high when it is blowing cold, like 300+ but the low side stays around 25 like the picture shows which seems too low. That was taken during a "stabilized" period, i.e. warm.
I will try to video how high it actually registers during the few seconds of cold. I do hear lots of hissing at the expansion valve when it is blowing cold.
I am not sure why the over pressure plug blew. I would have thought an over pressure sensor should have cut it out when too high. But not sure if it just prevents the compressor from coming on when the pressures are too low. Or is it supposed to do both? I also know the clutch burned up pretty well with rubber melted everywhere which tells me something didn't turn off when it was supposed to.

 

Realoem.com has an exploded view of the ac system. That might help with locating the sensor. You will find part numbers there as well...

 

Thanks. Any idea where it is located? A picture would help. The RealOEM site only shows the sensor in mid space.

Never mind. Note to self: Always look in the shop manual before asking dumb questions.

 

Well the evaporator is in the dash, middle. So I’d guess there.

If you can get inpa working you could possibly get readouts of the sensor...no need to replace it if it’s reading right.

thats I guess on my part that inpa will provide ac info. I have inpa working but for the engine module only.

i posted a few days ago...would like to get it working with all the other modules. If I do I’ll ping you

if I were you I’d search YouTube for your symptoms. This seems like an issue that is distinct

 

If I had to guess, I’d say expansion valve...but really not an ac expert. Maybe search symptoms related to bad expansion valve

 

Anyone know what this bolt on the a/c compressor is/does? I was doing some work, not paying attention and loosened it rather than the retaining bolt for a second. A small bubbling amount of neon fluid escaped before I tightened it back down. Torque specs? Do I need to be concerned with pressure? There wasn't a prob with the a/c or anything, I was working on something completely unrelated. And the car hasn't yet been started.


05 cooper S convertible manual transmission - R52 A/C compressor What is this bolt?
Bentley manual and my search online hasn't yielded any results so far, any help is greatly appreciated!

 

That's the bolt to drain compressor oil once the compressor is removed from the car. If that is removed, refrigerant will be lost as well as some oil, so definitely leave it alone.

 

Any idea where I might find the torque spec for it and should I be concerned about any pressure variables for the small amount lost? (not enough to drip)

Thank you sooooo much!

 

If you closed it immediately, there's probably nothing to worry about. As for torque spec, I don't know. I would guess around 10 Nm.

 

Thanks so much!