No heat but AC works strange noise drivers side under the hood

I'm a new member and I have a problem that I don't quite understand. The heat quit working completely and now I have a box right behind the battery making a fast paced hissing sound

 

Welcome from Wisconsin!

 

Welcome. Not sure of the housing box you're referring to but sounds like a vacuum leak by your description. Vacuum leaks Usually won't hinder heat, since it's a system to reroute the coolant through the heater core. But hard to say with knowing what you're seeing.

No leaks on the ground or inside behind the passenger glove box area ? Only the housing sounds that you know of?

 

Welcome from Arizona!
Maybe it is a mouse giving CPR.

 

The "Box" behind the Battery is the Fuse / Relay box the "hissing" sound could be a bad relay buzzing or the results of failure of an electrical component like fan motor causing the relay to buzz, if you don't have Electrical skills I would find a shop to look at it because you can make it into a way worst problem Don't be the person who does not really know the system and go in start moving and changing stuff then scream when it cost so much for it to be traced down to fix (nothing like fixing owner created problems before finding the Original problem and having to explain why it cost so much to fix 1 loose wire).

 

X2 ^^^


See this happen all the time..

Btw, welcome to the forum Larry