was on a trail one day and it got to harsh so i went to turn off the trail which i thought the jimmy could handle but bottomed out/ smacked the front end it was hard to tell as it happend at about 2 am(dark)
no visual damage that ive seen yet but now once in a while ill turn my heater on and nothing! just a hissing noise. then other times it works fine, anyone have any ideas, its already -20*C during the day and id like to have heat.[:@]

 

ouch, that sucks! hows the coolant level? does it have an ambiant air temp sensor? if so, that may be damaged.

 

Sounds like you knocked a vacuum line loose. Where do you hear the hissing noise?

 

hissing noise is coming from the vents, like when you fade them in and out, if i did knock a hose loose it would'nt work at all right? it just works when it wants too, and when it does work it works like new[>:]

 

Sounds like a cracked/broken line. Eventually it builds enough pressure to move the vents.

You will have to pull hte switch and maybe the radio to see where it is leaking. Its been a while since I pulled mine out, and I have replaced several of those switches on different years so forgive me if I am off a little here. Thee should be at least one if not two elertrical harnesses plugged into the switch, there should also be a clump of vacuum hoses, multicolored, held in place on the side of the swtich, careful when removing the switch, you don't want to break that fitting off. Then there should be a cable attached to it as well. To get the switch assemble out, should be two screws under the dash, take them out and let is slide down and out. Don't force it. They are noit cheap to replace.