hissing sound?
 

hissing sound coming from passenger side firewall. i notice it when at idle or when coming to a stop. no vacuum leaks i can find. jeep is running fine. but its kinda loud...maybe also associated with a relay clicking on and off? any thoughts guys?

my 1990 Cherokee has the same thing, and I've never figured it out. I thought it was AC related based on what someone told me, but I've never been able to confirm.

So I'm interested in the answer too :)

if it's not a vacuum leak than I have no idea?

well maybe it is a vacuum leak that i just cant find? how would i go about finding it? besides a hissing sound what would the symptoms of a leak be?

Snakes in a Jeep:

Starring: Samuel L. Jackson

:rofl:

J/K I have no Idea

does the brake booster make noise? i swear it has to do with slowing down or something.... and a little click like a relay. ill try and take a video of it today. im not so sure somethings wrong...i just want to know what it is ya know. for my further jeep education

there is vacuum hoses on that side to control the vents

Easiest way to find a leaking vacuum hose is to get a can of carb cleaner, and while the truck is running, shoot a little into the area the hiss is coming from. If a vacuum hose is leaking there, the carb cleaner will be sucked in causing the engine to rev lightly, not a lot, just enough that you'll hear the difference.

Also, do you have ABS? There is some kind of pump related to the ABS system that sits in the passenger side corner of the engine bay, right by the firewall.

how do i know if i have abs? i might. i feel stupid that i don't know. but its a new jeep, like 6 months, and i'm learning. i assume it has abs. how do i know?

I've had the same problem with my '01 xj for over a year on the driver side. I've tried Brak Cleen to find the leak to no avail. It also surges sometimes when I get over 45 mph. Please Help!

mine was a bad booster

The brake booster was making the hissing noise?