97 jeep tj possible vacuum resevior/ canister issue

[luis]

I have a 97 jeep tj 2.5, 5 speed. Iv had this issue for awhile and I finally decided to correct it. When I have my ac kicked on and I'm driving down the road the cold air would be forced to the lower air vents or the defrost area not really sure but to get the air back to the top vents I need to roll of the throttle and slowly get back on the throttle to correct this, iv already check my check valve going to the vacuum resevior and its working not really to sure what's going on here, I do know all the vacuum lines are good and solid no vacuum leaks at all. I think it may be my vacuum resevior but not 100% sure, thank for taking the time and looking at my post

 

[JPNinPA]

This is a vac issue. There is a leak somewhere you just didn't find it yet. I recently this year read of a similar issue where the owner traces the leak to the vac lines at the select switch knob. First check your blend door and connection to it. Then trace each vac line and connection. The vac resivoir is under the battery.

 

[luis]

Ok I will try that. How many lines are there that have to to with the ac? From that picture you sent me it looks like one main line

 

[JPNinPA]

There are many connections starting at the intake. Check them all. The 97's have an extra port on the intake that is capped off. Don't forget lines to the brake booster could be at fault. However, leaks this far back would cause high idle or too lean conditions.
There is one main vac line that t's off at point 2 and continues to the res. From the res there is one to go to the trans (auto). If you gave vac based lockers there would be additional T's.

At point 2 the vac for the HVAC goes through the firewall. Don't shrug off the inside the cabin lines. This is a small leak and a big headache. Inside the cabin they branch off to the select switch. Not sure if there are more in there. I' have to look behind the dash.

 

[luis]

I'm gona hunt that down tomorrow, thanks for your help I really appriciate it

 

[luis]

I may have found the issue, there was a vacuum hose that was poorly installed by PO, seems to have done the trick, thanks for your help it was much needed

 

[JPNinPA]

:beer:

I may have found the issue, there was a vacuum hose that was poorly installed by PO, seems to have done the trick, thanks for your help it was much needed

:beer: