2014 Passat tsi 1.8t Heat question

So i am getting rdy to buy this car and i found out the heat doesn't work well at all. I didn't even know it didn't work when i took it for a test drive i wasn't looking at the heat since it was 50-55 out. so when i finally got it to drive home tonight i was on the highway and i was like brr its cold. I turned the heat on and it was piss warm on the drivers side and ice cold on the passengers side. Its all the way7 through even on the defrost and floors as well. Cold all the way through and luke warm drivers. So could this be a blend door or heater core? I heard the heater cores are easy to do on this car

Anyways

The paperwork isn't fully finalized and i can ask them to fix it or i wont buy it. Anyways beautiful car. rides great runs awesome. reminds me of my b5.5 1.8t. Whole story is they screwed us twice with blind promises and now they wanted to make it right. we had deposits on 2 cars in the past 2 months and they sold both on us. I wonder if they will make it right and fix the heat in this car. They allowed us to take the car home because the fiance was taking a long time since its sunday and we can come back Tuesday. Since my wife is the primary owner i asked her to call and see if they will fix it.