Hissing from passenger side vents with AC on

[pheel85]

Hey all, I am new and glad I found this site. Anyways I just started having this problem, with my AC on and running I hear a hissing noise coming from my passenger side vents and it lasts about 3 seconds goes away for about 15 than starts to hiss again and repeat this cycle. Does anyone know if this is low refrigerant, or maybe a vacuum line ( its crazy I know thought I would ask) i'm pretty good with cars but this one has me stumped and I really don't wanna pull my dash unless I have to. I can put the fan speed at any speed and this happens...im stumped and any help would be great...I have a 2004 expedition with the 4.6L engine....


Thanks...Pheel

 

[jjbusa]

Same here.

 

[pheel85]

I found the problem its a sensor in the black hvac box behing the glove box dont know the actual name but got a pic

 

[jjbusa]

Sweet lmk when you have a part number and check rockauto