Something people don't really think about until they get out into the world to do their RV camping is that these units can get stuffy and hot really fast without proper ventilation. The other side of this is that you can get really wet during a surprise rainstorm if your vent seal has dried, cracked or broken away from the underside of the latch and hood. Another situation may be you don't feel the vehicle has enough ventilation for your needs and probably should have more to allow for better airflow.
Step 1 - Find a Good Location
If your unit has vents in the front and not in the back then this is where you are going to place the new vent to allow for airflow throughout the unit while your RV camping. This allows for the air to freely come in and out with the outside wind and air pressure, allowing for heat to escape quickly as well, keeping you cooler. Be sure the area you are going to install it is free of obstructions or other wiring, lights or devices on both the inside and outside of the vehicle. Once you have the perfect spot, trace around the vent casing to get the dimension of the hole you are about to make.
Step 2 - Cut into the Roof
Carefully cut the hole out of the roof where your vent is going to be going, and be sure to drop rags or a large cloth on the inside of the unit as your working, this will prevent particles from getting on your interior. You do not want to ruin your future RV camping experience by stepping on a strip of metal. Being accurate in this part of the process is imperative as any off cuts can cause the seals not to fit properly allowing bugs and the weather to get inside.
Step 3 - Installing the Ventilation Unit
When you are RV camping you will not want the weather or bugs getting into your domain, so spread a nice layer of sealant on both the top and bottom of the hole around the edges and press your vent casing into place tightly. Once this is done you can drill the holes for the hardware screws that came in the kit. There are many makes and models of vent systems, and you will want to read the instructions carefully before starting the project to make sure there are no added steps to be taken.
Step 4 - Replacing Old or Worn out Seals
There is nothing worse then having the weather or bugs in your personal space when you are RV camping, and when the seals on your vent become worn cracked or torn, you will want to replace them. It will depend on the make and model of your particular vent system as to whether there is simple seals that can be pulled out and replaced, or if you will have to remove the entire unit and install a new one.