Here is something new. I start the 400 and while I give it a second to warm up, I hear a hissing noise coming from the rear deck. Turns out that the AC compressor is engaged. So, I pull the wire thinking its a electrical issue and nothing. It just keeps going. Guess I'll cut the belts till next summer. If it's not something, it's something else.
Yes. I cut the belts. I guess I'll install a new compressor and clutch in the spring. Before I cut the belts, I tried to hold the compressor still with a piece of wood while I cranked the motor to see if it would free up.
Hey Mark when you do your a/c work please keep us informed. There does not seem to be a lot of posts about the a/c system.
OK, sure. Just as a note: when I switched to R134a the compressor clutch would slip a bit if I gave the system a full charge. This probably turned the clutch pads into hot-glue. I'm not sure if I started out with a weak clutch or I need to alter something to run R134a. When I flushed the system before the change over, I found it was filled with black muck. Maybe I didn't get all the muck out before the recharge. I don't think these compressors have a over pressure bypass, so a clog would really load it down. Just below the high switch cut out
My 400i was converted to R134a several years ago. It continues to have a very slow leak requiring a re-charge once a year. I've had a mechanic do it for me, but I should be able to do this myself. How hard could it be? I am looking for detailed, step-by-step instructions for this process, the pressures high and low that are ideal for these compressors, and most importantly for me - what not to do. Any help would be appreciated.
The clutch can be replaced without replacing the compressor. It is a Japanese clutch. I posted part number about 2 years ago. I only found them available in Canada and Australia (at least where I could read the site info). If you need the part number I can dig it out. My clutch had seized completely. Ken
I can send you a PDF of the A/C section of the workshop manual for a 400i, if you wish. This seems pretty comprehensive and lists the relevant pressures. Just send me a PM with your email address.
I have the workshop manual and should have looked there first before posting. Are the pressures the same with R12 and R134a?
Absolutely not. The conversion from r12 to 134a is a lot more complicated than simply venting the Freon to the atmosphere and adding three cans of 134a, plus doing that is against the law in most places, particularly in the U.S.A. Do the conversion incorrectly and your compressor is likely to fail. Here is some basic information that may lead you down the correct path. AIR CONDITIONING HELP HOME PAGE,a/c,ac,air,air conditioning,barrier hose,Behr,Bosch,compressor,compressors,condensers,condenser,condensors,drier,driers,dryers,evaporator,evaporators,freon,Griffiths,improvements,Kuehl,Nippondenso,Porsche,r12,r134a,San
I have shot freon into several different cars with good results every time. Check Youtube for how-to videos. The cans themselves come with instructions as well. A meat thermometer in the vent -- the instant-read kind with the thin shaft -- is helpful as well. There's a sweet spot with respect to pressure where you'll get the coldest readings. Too much gas and the temp rises. Personally I have always found AC shops to be the worst pirates in the automotive repair biz. Highest prices and the worst results. Parts changers with bad attitudes.
The conversion was done correctly many years ago. My question was whether the pressure in the system was the same with R12 as R134a.
To properly swap over one thing you need to swap when going from r12 to 34 is the orifice. 134 requires a different size. I have not yet swapped this out on my car since I think you pretty much need to disassemble the entire dash to get to it. On my car the high pressure is a little too high while the low is too low. Since I live in a place where the a/c is not really needed that much I'm going to wait until I decide to recover the dash. A set of a/c pressure gauges really aren't too expensive.
A retro-fitted R12 system using R134 needs less refrigerant, around 15% less if memory serves me correctly. If you are trying to compress liquid the clutch(at least) will certainly suffer.
