Peugeot 307 HDI 110 hp

Hello, I have a 307 HDI 110 hp. The problem I'm having is that when I turn on the climate control, hot air blows out of all the vents on the driver's side, even at the highest temperature and speed. On the passenger side, it also blows hot air through all the vents, but it works perfectly.
A Peugeot dealership told me the repair would cost around €1,000. Is this accurate? Do you know what the problem could be?

Thanks in advance.

I don't know if it works perfectly, what's the doubt?

From what you've said, the problem is with the climate control unit, and if that's the case, your only option is to replace it.
Best regards.

On the driver's side, it works by blowing air at maximum heat and speed. On the passenger side, it works perfectly. It's a dual-zone climate control system.
Thank you.

Air conditioning calculator? And how much does that cost approximately?