1999 Honda Accord Hot air from the blower at startup

I have 1999 Honda Accord and recently had to fix the Evap two valve assembly beacuse of vapours leaking. After a month, I have this problem, when engine starts up and running for sometime it blows hot air from the A/C blower, although outside temperature is cool. Once I turn the A/C on and have the car running for sometime then the compressor make it cool and I switch the A/C off.
After that, I wil not get hot air as long as the car is running.
Why is this problem coming at startup? Is it related to replacing the Evap 2-valve assembly?

Thanks!