Hey guys, I recently had an AC system installed in my 240z, it's a second generation 280z AC unit and I had an issue with it since I kept feeling hot air coming into the car at high speeds. So after a bit of checking I noticed two leaks from the firewall which i sealed off and one more larger hole on the passenger side, under the dash that brings in air from outside (picture attached). I ended up sealing that large hole as well with insulation foam and it solved my hot air coming in issue BUT, now I have another issue.
I can now smell exhaust fumes in my car. My theory is when I sealed that large hole the air pressure in the car changed and it is now sucking or letting air in. Does that make sense?