zr2 blazer. vacuum leak (sound) under dash near a/c control

My son's 2000 Blazer ZR2 has the sound of a vacuum leak under the dash near the A/C control. I am sure it is the sound of a vacuum leak. A hissing when the control is turn to A/C on. Seems to steal vacuum assist from the braking system and when applying the brakes. Not sure of this, just seems to... sometimes. Braking seems to change the intensity of the hissing also. The truck runs fine.

What is the best way to get behind and take a look and repair? Remove the shrouding pieces under the dash and come up from underneath, or remove the bezel around the complete dash and go in through the front?

Has this been an issue for anyone?

Thanks in advance.

If it is hissing it is a vacuum leak.
You will have to look under there and try to spot it.
If you cannot see it from under side pull ac controls out of dash and look there.
A leak under there usually does not rob brake booster of vacuum.
You may haver another problem there.
Good Luck
MT