First question. SO for the past couple of days ive been commuting to DC (2 hr drive each way) to work on some lady's basement but i finaly finished. The problem im having is with my air conditioning. I rarlely use it in the first place and on the first day i use it, it works fine. 2nd day it just blew out hot air. imagine a 2 hr trip in 90+ degree weather with atleast a good hour stuck in traffice in the city. I triead eveerything with the controlls but it just blew out hot air. There was no weird sounds or anything. When i got home i let the engine cool off then tried it but it still blew out hot air. What could be the problem?

The 2nd question is what is the difference between 4-2-1 headers and 4-1 headers?

 

AC: https://dodgeforum.com/m_852051/tm.htm

4-2-1- 4 runners merge to two runners then to one
4-1: 4 runners into one

 

lol i know how the 2 setups look talking about performance issues. Does one allow more air flow, things like that. But thanks for the help