ac only blows cold air at highway speed. Warm or hot at idle. on 2006 Pontiac Torrent

Temp gauge in rearview mirror showed 140 after five minutes in drive thru. Fans have been replaced, cooling system flushed and filled. What should I check next, this is becoming a money pit, and nothing is fixing the problem.

Asked by for the 2006 Pontiac Torrent
add freon ..or add antifeeze