I have a vacuum leak on my 2000 Cherokee Limited and cannot for the life of me locate it...I found a broken plastic line broken off behind the passenger side headlamp and fixed the problem with new hose from vacuum canister up to the cruise control T connection but there is still a leak. I have looked everywhere but did not inspect the canister...do these fail? Looks improbable, but thought someone might have had a similar experience...TIA

 

It's plastic and a quarter of a century old, sure it can fail.
But to see if it's actually leaking,and you don't want to take the bumper off, just find the vacuum line going to the canister, hook up your mityvac, and see if it, and/or the line , is leaking and go from there.

 

What exactly is your issue? Does the fan only blow out the defrost? Is your check engine light on? Does the engine idle high?

 

You don't have to remove the bumper to get at the cannister, only the left end cap.