Manifold Pressure Gauges Readings with the Hood Up or Down?
When you’re performance testing an auto A/C system, should you take pressure gauge readings and duct outlet temperatures with the hood up or down? When you think about it for a minute, it may appear pretty difficult (not to mention tricky) to get pressure gauge readings when the hood is down, but there is a good reason why you may want to. Understand that the air inlet for the A/C system is right at the base of the windshield. Typically, the air inlet will be covered with a screen to prevent debris and other foreign material from falling in. You should also notice that between the air inlet and the engine compartment, there is a long rubber strip that runs the entire length of the firewall. That’s a really important piece of rubber when it comes to keeping you cool!
