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Discussion Starter #1 (Edited)
On the drive back from Pahrump (Ron Fellows) last night I was quietly cruising in the mid 70s (on cruise control) and noticed two peculiar things happening to RedHot: She seemed to have a very slight surge on and off and the temperature was getting pretty cold in the cabin (outside temps were in the 90s). I focused on the rpms and noted a slight quick run up and drop back of about 100 rpms even though the actual speed seemed to be remaining fairly constant. At the time I guessed it might be related the the AC compressor cutting in and out. Took the AC system setting off "auto" and that seemed to smooth it out, but the temp still seemed to be too cold respective to where it was set. Today when I checked our TSB/Recall section I saw the "HVAC Temperature Fluctuations" write-up and that seemed to be what I was experiencing (even though the write up did not mention the variations in the rpms, but that intuitively makes sense to me to be related). When I get a chance I will schedule a service for her and bring in the HVAC Temperature Fluctuations write-up. Let you know what they find.:cool:

Update: Got an appointment with my dealer tomorrow so I should know what they find.
 
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I am looking forward to the results from your dealer visit. This is the only issue that I am having with my car. Not a huge deal, but on a 2 hour trip the cabin gets colder and colder and I keep raising the temperature up ( doesn't help). I haven't notice any fluctuation in RPMs.
 

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Discussion Starter #3
You are correct in that normally I did not notice the related rpm pulse in the past when I had the temperature get colder, but this time I was on cruise control on a flat road and carefully studying all read outs when I noticed the 100 rpm change occurring. It was very subtle feel- much less noticeable than the V4-V8 shift, and it was a pretty quick run up and then return in rapid sequence. That's why I think it was related to the AC compressor cycling. But we will see what my service department says shortly. It will be in the shop for evaluation today.:cool:
 

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Low refrigerant levels would cause compressor cycling also. I've read a few reports of a AC gas leaks due to a system brazing issues by the system supplier. Hopefully though the re-flash will fix you up.
 

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Discussion Starter #5
Low refrigerant levels would cause compressor cycling also. I've read a few reports of a AC gas leaks due to a system brazing issues by the system supplier. Hopefully though the re-flash will fix you up.
We'll see, it been over at the dealer and I have not heard back yet.
 

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Discussion Starter #6
RedHot was fixed up with a couple of software updates: PIC5976 (specific to the HVAC issues I was experiencing), and then PI1101B for "HVAC, IPC, BCM AND RADIO". All performed well on the short ride home. Real test will be when I head out to Ron Fellows next Tuesday.:cool:
 

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Discussion Starter #7
Low refrigerant levels would cause compressor cycling also. I've read a few reports of a AC gas leaks due to a system brazing issues by the system supplier. Hopefully though the re-flash will fix you up.
Fortunately low refrigerant was not an additional part of the problem. All issues resolved by thePIC5976 (specific to the HVAC issues) and PI1101B which handled updates for HVAC, IPC, BCM and radio.
 
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