1988 acura legend wet carpet problem

My son inherited 1988 Acura Legend form grandparents. Passenger side of carpet towards rear and middle (not front) is constantly wet. Cannot find any external leaks. Noticed that there is heater vent under seat. This is where carpet seems to be the most wet. Let heater run for over 30 minutes and could not detect any moinsute coming from vent at this time. Could the moisture be coming from somewhere else, or is there something I am not detecting about the heater vent?

I don't know a whole lot about the Legends but it sounds like the heater core to me.

if it is the heater core leaking...a good sign would be low coolant & coolant odor inside the car. moisture could also be caused by a clogged evaporator housing drain hole. i'm sure you have noticed on other cars that when they have the a/c running....you'll see water dripping from under the car. well if this drain plug is clogged...then the water has no where else to go but into the car. you can remove the evap core yourself...however you need to be a licensed mechanic to handle the freon since your dealing w/ r12. an easy TEMPORARY solution is to safely jack the vehicle up and get underneath...look in the area where you normally find it damp and you should see a rubber tube sticking out from the fire wall. get a flexible wire brush and remove if possible any gunk thats built up. if you cant remove the gunk...then try pushing out the way of the hole. becareful not to damage the evaportor. this may or may not fix the problem...but it's worth a shot if you're looking to save some money.

I had the same problem in my 90 Legend and it took me a long time to figure it out. The drain line from the sunroof evidently had a defect or was damaged. The plastic or rubber drain line runs through the body roof support column and drains behind the front wheel behind the mud flap. Even with the line unplugged it was still allowing water to get into the car from somewhere up under the dash. I had to end up plugging the front left drain port. Now I have to be careful and make sure the car isn't parked with this corner too low when it is raining.