Can somebody explain to me how the A/C system works, from compressor to condensor, condenser to evaporator, etc? My A/C compressor is putting tons of parasitic drag on the motor, I want to be able to troubleshoot/diagnose this.

While we're at it, here's what's happening:

• When the A/C is on, the compressor makes a whining noise and I lose TONS of power.
• At freeway speeds, this translates to the car slowing down even at 3/4 throttle.
• A/C is not blowing too cold.
• I'm getting a blueish deposit on the inside of my windshield from the top vents...assuming this is related to A/C?
• No weird smells, though.

 

From what I know about the R53 is that the AC system pulls virtually all power from the car. Sounds like your compressor is bad. It's either bad or needs oil, if it's needing oil, you're leaking oil in most cases. If it's not cold you're leaking. If you're getting deposits on your vents and it's blue, your heater core is leaking coolant. The AC Evaporator could also be leaking and you have very low (if any) refrigerant. If the compressor still kicks on your car's previous owner or you may have bypassed the low pressure switch, didn't fix the actual leak and it now just runs without/very low refrigerant which really is what led to your current situation. I'd say new compressor and maybe an evaporator if that's where your leak is. It could just be at the compressor. You can do this work yourself and have it then filled at a service shop or you can buy you a few cans of R134a and do it yourself. It'll be kinda intense but keep track of your fasteners and pieces and take your time. Get a compressor that's pre-oiled so you don't have to worry about the oil. The blue deposits are from your blue MINI/BMW coolant, you'll need a new heater core at least. Basic AC layout below-

 

What's your coolant level look like? Note, the leak could also be up front at the condenser. Rocks can get thrown in there and damage it. Look for a build up of dirt around the system, connection points on the compressor, for the condenser look for damage and dirt around said damage. Dirt builds up around AC leaks.

 

I'll check coolant levels tonight. Difficulty is not an issue, I just did a bunch of engine seals/subframe work by myself.

The deposit is not on the vents, it's just a thin film on the inside of the windshield. Not really blue either, just darker than the glass to the point makes it hard to see at night. Could it just be refrigerant?

Is it worth taking to a mechanic for an inspection? Or should I just replace the compressor first and then take it in? What are telltale signs that point to a bad evaporator?

Could it just be a line? What about gaskets? I had the condenser removed when I had my front end disassembled this last month, could have put stress on the lines.

 

If you're getting a discharge and you're sure it's not coolant it's your evaporator leaking refrigerant. But I'm not sure a refrigerant leak would leave anything like a residue, maybe the oil would,but refrigerant though it would just evaporate. Could it just be condensation from the glass itself being cold? Try blowing the ac out the vents that face into the car, maybe hold/tape a piece of paper or paper towel and see what collects on it. If you've had the compressor off and it lost any oil that could be the cause, also, the fittings are pretty much a one time use sorta deal. If you look at your compressor connections and they're real murky with alot of dirt around them there's your leak. The windshield has me wondering though. Maybe try some new seals at the compressor if that's possible. I've never dealt with a MINI AC compressor. Maybe throw in some refrigerant with oil already in it since it' sounds like your compressor is going/gone just for shi#s and grins to see if that quiets it at all. I'm sure if you throw refrigerant in it'll cool down your AC but if you've got a leak you have to sort that out or you'll be throwing alot of refrigerant in the air.

 

You can get a leak detection kit at an auto parts store. It'll have some dye and a UV light. The dye will look like little neon green specs. If your your evap is leaking those little green specs will show up on the windshield, and if it's leaking at the compressor fittings you'll see them there too. I will warn you, unless you find it right away it can be kind of a pain to isolate a leak(s). But to me, since you've had your compressor off you'll probably have the normal leaks at the compressor.

 

What you'll need- you can find these items at any auto parts store. You need the dye and a light. I've used those glasses only once, but they can help you see the green specs better.
http://www.oreillyauto.com/site/c/de...1786&ppt=C0050

 

To clarify, I never disconnected the compressor, only detached it from the motor/drive belt when I was fixing my oil pan gasket leak.

It was working fine before, then I disconnected it while working on the car, then 50 miles down the road it started making noise and 100 miles down the road it made the car undriveable.

 

Can the shaft of the compressor have been damaged while changing the belt?

There is oil in the refrigerant mixture that lubricates the compressor. If it is leaking out you may have a sezied compressor.

 

Possibly but I doubt it. I think tension/stress on the lines going into/out of the compressor is more likely the cause and that I assume, will be one location for potential leak. Sounds like the evaporator could be leaking as well. With an AC system you never know.

 

you're in Atlanta?

Go see WAY .....

waymotorworks.com

altho ANYPLACE that does auto a/c can do a leak check and check your gas levels . . . nothing special about MINI a/c until you need parts

 

No, I'm not. I'm in Phoenix, Arizona.

I buy my performance parts from them. For example, I ordered my heat exchanger, oil pan gasket, crankshaft position sensor, TSW upper mount, BSH lower mount, PowerFlex gearbox mount/LCA bushings from Way.



I'm a college student who is trying to save my money, a shop isn't an option. If it was, I wouldn't be crying for help/asking for someone to explain how something works on the forums haha. I'm a mechanical engineering student, I do all my own work and repairs, which I learned how to do from the forums.

I need to learn how to diagnose this, not be told to take my car to someone else for them to fix it. I'm just going to reference my original question:

 

sorry got the posters confused

improperly messed with a/c not only costs money but damages the environment

sometimes the least expensive option is going to an expert b4 you REALLY screw something up.

 

Already tried, my man. My family mechanic quoted me between $1200-1500 for the repair without looking at it, recommended the whole kit considering the mileage and the multiple faulty components.

I got C/V boots and a subframe drop right the first time with no training, might as well try this. Especially since I'm leaking refrigerant already, wouldn't it be worth taking a stab at replacing the evap & compressor? Sounds like those are the issues.

 

I was super careful when doing the repairs. It's more likely that I damaged a line getting the condenser re-mounted (awkward, sketchy movement required) than it is that I damaged the compressor, I certainly didn't let it just fall off of the motor, haha.

Would the oil be leaking from the bottom of the compressor??