AC issues in an 08 Limited CM

I have what appears to be an odd problem with my 08 CM and the AC system. When its cool or cold outside my AC and Defroster work fine with no issues, when its warm or hot(75 and up) outside none of the system works. The system lites up and is getting power but the system wont switch on or start to blow.
I've scoured the net for the last few days and can't seem to find any info on why this is happening or how to fix it, ANY help would be grateful. Thanks Howard

 

Possibly the relay? I am no electronics engineer, but when it gets warmer maybe the contacts are expanding in a way that that they no longer make connectivity, however when its colder, they don't expand as much.

 

Do you know if blower/motor has been changed?
Recently replaced blower/motor assembly in our 07. It just quit working. I was able to measure voltage at the harness to diagnose bad fan motor. Voltage was 0-12 Vdc variable, linear to fan speed control knob.
Maybe you could try to measure voltage when the the problem is present. If voltage is present then it would point to bad blower motor. If no voltage then something upstream, maybe the fan speed switch or relay mentioned.

 

Was just reading about some similar issues. Mine has a delay before the fan will start to blow. Some people said there are sensors that delay the system until certain temps are hit but yours sounds a little different. Try tapping on the blower housing under the passenger dash. Sometimes that will start it up and tell you where to start looking.

 

I ended up replacing the blower and motor under the dash and the fan selector speed dial and its been working great