If your hood vent is leaking when it rains, there are a few possible causes. First, check to see if the vent is properly installed and sealed. If the seal is not tight or if the installation is incorrect, rainwater can easily enter the vent and cause leaks. Another possibility is that your gutters are clogged or malfunctioning. If gutters are not draining properly, they can cause water to back up and leak into your hood vent. Finally, it's possible that your roof isn't pitched correctly or that there are other problems with your roof that are causing rainwater to leak into your home. Regardless of the cause, it's important to fix any leaks as soon as possible to avoid damage to your home.