U0164 Error code

swoopdeville

I have a service engine soon light with an associated error code of u0164. I have seen a few posts concerning this which all say its a CAN communications error but I haven't seen any resolutions to the issue. The service manual seems to point to a communications error as well between the HVAC control module and the DTC. I have replaced the HVAC control module but the light has returned. My AC was working with no issues until recently, now it doesn't work all the time, sometimes it blows warm air but I think I hear the AC compressor click on. Anyone have any ideas of what to look at next? Its a 2009 Base model with 32K miles. Unfortunately the light came on about a week after the warranty expired based on time so if I take it to the dealer I will have to pay some $$$.