A/C System on 2004 Dodge Ram 1500

When the truck runs idle, hot air starts to come out. When truck is running at normal speed on the road, the A/C blows out cold air. What is the cause of this or what part of the A/C system is going out?

Asked by for the 2004 Dodge Ram 1500
Lack of freez-on you may need to recharge the A/C System
1 more answer
i had the same promblem with my 1991 ford f150
its the ac compressor wearing out to make sure
that is whats going on check the low side pressure
to see if the pressure fluctuates between 25 and 50 psi
if it cant get 30psi or lower while idiling on a 80 degree day
its your compressor assumming that it has enough freon in it.