Chrysler Repair: 95 LHS: fans/idle speed related to ATC use?, automatic temperature control, chrysler lhs

Question
I have a 95 Chrysler LHS with the automatic temperature control hvac system.  Anytime I turn on the ATC, the cooling fans turn on and the idle begins to goe up and down.  This happens even when the engine is cold.  I do not know where to begin looking.  Please help!


Answer
Hi Art,
Everything you describe is normal IF you have the ATC set for either cooling or for windshield defrosting. Those two setting require the AC function and thus the compressor and when that is chosen the fans come on automatically. The compressor cycling will cause the idle to vary as well.
If you believe that there is something the matter with the idle speed regulation you can try to find out whether the engine controller has recognized that as a problem. Use your ignition key to get any fault codes read out from the engine controller memory:
"On-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. The check engine light will remain "on".  Then watch the check engine light which should begin to flash-pause-flash-etc. Count the number of flashes before each pause. Then repeat to assure an accurate consistent count. Then group the counts in pairs in the order of appearance to form the 2-digit fault codes. The last count pair will always be 55 because that is the code for "end of readout".
Then go to www.allpar.com/fix/codes.html for a list of what the other code numbers mean. Then write back for advice.
Roland