Climate Control Channel 11 (alternator voltage)

Phil Rose pjrose at
Sat Aug 21 20:07:34 EDT 2004

Well, now I'm convinced: An open circuit at the A/C low-pressure 
switch--caused by low refrigerant pressure or disconnected 
connectors--will cause the readout from Climate Control Channel-11 to 
be stuck at a value of 12.0 (Channel 11 reports alternator voltage).

A little history: Last summer I had the A/C system converted to R-134 
and consequently had the A/C working for the first time since we've 
owned the car. Soon afterward I noticed that the CCC-11 was 
mysteriously functioning properly--showing a variable alternator 
output voltage--rather than just the steady "12.0" value that we'd 
previously always had (with this car). At the time it was just an 
interesting coincidence, which I posted about last summer.

After a while, A/C system leakage caused the refrigerant pressure to 
fall so low that the A/C quit (with the low-pressure switch in an 
"open" condition, according to the CCC-17 diagnostics). And 
coincidentally, when I next checked the CCC-11 value, it had again 
become frozen at "12.0". Yesterday I finally got around to recharging 
the A/C with a couple of cans of R-134. After the A/C began working, 
guess what also happened: Yep, channel 11--simulauditaneously--was 
back in normal operation. I imagine there might also be _other_ 
situations that can cause CCC-11 to become stuck at a value of 
"12.0", but now I'm  certain that an open-circuit at the A/C 
low-pressure switch is one cause.


Phil Rose				Rochester, NY USA
'91 200q	(140K, Lago blue)
'91 200q   (64K, Tornado red)			mailto:pjrose at

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