Mini Cooper S 2002 Hatch Air Condition Debug

[UCDNebulous]

Hello All,
This is my first post on Pelican Parts, but have been lurking for quite a few years now. Unfortunately the guys over at MiniMania tell me I don't have a 'Real Mini' because it's not the old style and don't want to help me.

Either way, here is a little backdrop on my current issue and what I've done to try and debug. For what it's worth, I have done extensive searches on this site, on Mini Mania, and over the web to try and find more solutions.


Tis the season for Mini maintenance, and I've been trying to solve this issue for a little while. My mini is a 2002 Mini Cooper S hatch with less than 50k miles on it. I purchased it almost 8 years ago used from a collector who had been keeping up on routine maintenance but still needed a battery and air filter replacement.

A week or so ago the A/C in my car stopped working somewhat suddenly, at the time I was bothered, but knew that there could be a variety of reasons for this to happen. The first thing I checked was to see if the compressor is actually turning on. Without taking the car apart I am able to see that the compressor clutch isn't turning. I'm hesitant given the mileage on the car to assume that the compressor or compressor coil is shot. To ensure what the cause of this is, I have gone ahead and checked the following:

1) AC Fuse (Engine Compartment) 30A, looks and is not blown.
2) AC Fuse (Cabin Compartment) 5A, looks and is not blown.
3) AC Relay (Engine Compartment). When the AC is turned on in the car when idling, the click from the relay is clear and crisp, although it sound sound worn down. I bought a new relay for this and put it in. Much louder click, so I give this a passing grade.
4) r134a level. I took the low pressure cap off the AC system and connected my gauge. The pressure reading immediately went up into the red. I turned on the car and the pressure stayed the same in the system.
5) r134a test, to ensure the system wasn't staying off due to over-pressurization, I had a mechanic legally remove some of the r134a from the system. (EPA etc). This brought it down to the correct 'operating' pressure, but still the compressor clutch would not turn on.

I know steps 4 and 5 both rely on the compressor actually being on, because without the compressor turning on the pressure reading is not accurate or even correct. However this was the best I could try without the compressor turning on.

From here, if my lurking has served me well, I know that the possibilities are as follows:

1) Compressor itself is shot, $600 replacement + my time and effort to replace and a recharge.
2) Compressor clutch is shot. Can't buy this on it's own, and would need to replace the whole compressor.
3) Compressor coil is shot. $95(?). This is (apparently) a common problem on early new Minis. Would still require me to get the system drained, replace the coil, test it, and recharge.
4) One of the multiple sensors are telling the compressor that a different external situation is happening, and thus telling the compressor not to turn on. I don't know exactly how these sensors are wired to know if the relay would even activate if any of the sensors are tripped or not. Speaking of which, could someone knowledgeable on the subject tell me all the possible sensors that would be preventing the AC Compressor from turning on? I only know of the refrigerant sensor and the pressure in the system sensor.
5) If there are other things I haven't tested but should please let me know! I'd like to take every opportunity I can to learn more about my car.

From what I've said, where do you guys recommend I go next? I work daily and need the car to get to and from work, so leaving the car in pieces for more than a weekend isn't an option I'm excited to consider. If I need to replace the compressor I would be able to finish it over a weekend once the parts arrive.

The only somewhat straightforward test to do is check the OBD2 readings and error codes and try to deduce something from those. However with the Mini most standard OBD2 devices can't read the codes. I have one that for sure can at another property, but cannot access it until this weekend.

I have the time, ability, and money to replace the entire compressor, but I would really rather not.

Thanks in advance for all your help, and I will be happy to provide more information, answer questions, and take pictures if needed.

Regards,
Chris

[Dmitry at Pelican Parts]

Hi Chris and welcome to the forum! I can assure you that members in this forum will be happy to help you out and answer any questions that you may have. I think before spending money on any additional parts, get the codes read first; as I'm sure you know , this will give you a definitive place to focus the work on. In addition, I'm adding a link to our site's DIY tech articles on your MINI; these will greatly help you when doing maintenance and any repairs in the future. Please let us know if you have any questions!

Pelican Parts - MINI Cooper Technical Articles