Hello fellow C5 Owners and Enthusiasts,

Long time reader, first time poster here. I apologize in advance if the following is long, but here it goes....

My 1997 Corvette is equipped with the "Dual Zone Climate Control" feature. Periodically, while driving, the A/C unit will kick-on all by itself in the "Auto" mode. Now, when it does kick-on, it will always come on at 23 Celsius (or 73 Fahrenheit) - even if in the last time I used the "Auto" feature I set the temperature at say 20 Celsius. Similarly, sometimes if I have the A/C on at a different temperature and on a "manual" setting, the A/C unit will shut off, only to come on a few seconds later in the "Auto" mode and once again at 23 Celsius. When the latter occurs, I do notice that the external temperature may sometimes show an exaggerated temperature such as 39 Celsius, but then corrects itself a minute later. Pulling the codes when this occurs just reveals several loss of communication codes.

In terms of another MORE RARE oddity, on a few occassions (maybe three times in the last three years) I have noticed that the units displayed on the HVAC will change from Celsius degrees to Fahrenheit degrees on its own (my Corvette is a Canadian model, so the default units on the HVAC is Celsius). When this occurs and I pull the DTCs, the HVAC module just shows "NO COMM.". If I shut the car off, and restart it, all is well and the "NO COMM." returns to normal. HOWEVER, if I make the attempt to push any button on the HVAC while the units have changed and have not had a chance to correct itslef, all heIL breaks out!!!! All of a sudden the ABS and Traction Control warning lights will light up, and I will have the "Service Ride Control" and "Service ABS" messages appear. If I pull the DTCs, there will be "NO COMM." for the TCS and RTD modules. Once I shut the car off and re-start, all is well. When I pull the DTCs after re-starting under this scenario, one of the codes I notice is:

U1255 - Serial Data Line Malfunction or Generic Loss of Communications.

Noting the issues with the HVAC system - sometimes operating with a mind of its own, and periodically (i.e. maybe three times in the last three years) having an impact on the TCS and RTD, I figure something "electrical" is the culprit. Any ideas???? Grounding issue or Ignition Switch issue?????

Any suggestions are appreciated. Given its intermittent nature, it is tough for the servicing dealership to diagnose.

Thanks again!