CCU Code Reading 88 300E
 

Well, I'm trying to get my 300E out of moth balls. Since being an empty nester, my wife and I have accrued several two passenger fun to drive cars. My Dad is now in a Nursing home and we need to get set up so that we can haul my Mom around after she ran her car through the wall at the nursing home.

Anyway... several years ago I made the LED code reader for the diagnostic connector near the battery. I used it once and put it away. I am now troubleshooting the a/c system and can't get the clutch to pull in.

I did some searching and found on old thread of mine from when I made the tester and found that pin 7 was the diagnostic for the ACC system. I hooked up the tester, pressed the button to get the LED lit and then after releasing the button I then got one flash. Now I can't find that old thread so I'm hoping someone can answer my question off the top of their head.

I think that this one flash means that no codes are stored. Can anyone confirm this?

Thanks for your help.

"1" flash = no errors present and Pin #7 is the correct pin for climate control diagnostics.

I'm assuming you checked the low pressure safety switches, bad compressor coil maybe? Or perhaps clutch air gap needs adjusting?

Thanks Tim.

Yes, I already checked the pressure switch. I haven't gotten so far is to check Voltage to clutch or a resistance check of the clutch coil. I have only done a quick check so far.

Before I put it away, the compressor was kicking out due to the speed sensor from time to time. I also did a quick leak check with the sniffer and the compressor seal is leaking. Due to the common problem with the compressor wearing, causing the speed sensor to trip, if I am indeed getting voltage to the clutch, I think I'm going to go ahead and order a compressor.

Larry

Sounds like a reasonable course of action, I guess two decades of service life from an A/C compressor isn't bad, the Denso compressors are an order of magnitude better than the old R4's.

I put a new A/C compressor in my son-in-laws BWM wagon last week, I think it was the 4th time this year I've needed my A/C recycle machine.

Lots of A/C problems this year....

Okay, I shorted 15 and 87 on the KLIMA relay and the clutch pulled in. The low pressure switch is closed.

It appears at this point that I need to check for voltage to the low pressure switch. I went out in the heat and got the above tested and came in to do a little more research. From what I can tell the CCU actuates the clutch through the low pressure switch and then onto the KLIMA. Another input to the KLIMA is the rotation sensor, so there maybe a problem there.

I will try some more testing tomorrow afternoon. Any suggestions in the process are welcome.

Larry, what did the problem turn out to be?