I have an 06 2.6l buick raineer and the AC has been operating this summer fine only when the car is moving. When sitting idol the air is warm.
My first guess is the 134a coolant is low, only I can not find the high side line to attacht the hose connector.
Any suggestions?

Normally you would connect to the low side line I believe. But I agree, it would seem you are low on freon if sitting still is producing warm air.