Only defrost works - NOT vacuum reservoir!

[Pro_Marinero]

I've been dealing with only having the defroster vents work for quite awhile now on my '98 4.0 4x4. I've narrowed it down to something from the reservoir back as it is holding vacuum.

The vents will change when I switch from 2wd to 4wd, but the system will eventually lose vacuum and then not work again. The schematic shows a check valve and what looks like an electric valve from the 4wd. I'm pretty sure that I'm going to have to go digging for this one behind the dash. Has anyone else experienced this and have any advice? Thanks.

 

[Pro_Marinero]

I've been dealing with only having the defroster vents work for quite awhile now on my '98 4.0 4x4. I've narrowed it down to something from the reservoir back as it is holding vacuum.

The vents will change when I switch from 2wd to 4wd, but the system will eventually lose vacuum and then not work again. The schematic shows a check valve and what looks like an electric valve from the 4wd. I'm pretty sure that I'm going to have to go digging for this one behind the dash. Has anyone else experienced this and have any advice? Thanks.

Not behind the dash -- it's in the hubs. Off to fix those or make them manual.