I recently bought new rear shocks for my '03 Park Avenue Ultra supercharged. All was well until I took it to Kauffman Tire to have new tires put on. After they took it down off the rack, one rear shock was "locked" and would not budge.

According to Kauffman, GM does not require any sort of air release from the shocks when fully suspended for a period of time.

My normal mechanic argues otherwise stating you must never leave the shocks suspended for some time due to fluid not releasing (this is way over my head). he says this happens 30% of the time and requires his guys to drive all GM cars onto the alignment rack to not be lifted as high.

So...question is: can you lift this vehicle off the ground for a while and not worry about the air shocks "locking" up?

I'm now stuck paying the labor to install a new shock from my local mechanic. GM covered the shock itself under warranty. Trying to get GM to reimburse me.

Any insight is appreciated.

I have lifted the rear of my car many, many, many times with full extension of the shocks and have never experienced this issue.

Been there, done that, got the solution:

https://www.gmforum.com/buick-172/strut-install-fail-need-help-298461/

Simply put, the instructions in the manuals direct you to pressurize the system before putting weight on the suspension after installation. That is the step I missed, and I suspect your shop did the same. If that is the case, assuming the shock hasn't been damaged from the air bladder binding up, the rear end can be jacked up, wheels hanging in the air, the ELC system then needs to be triggered (this can be done with ignition on, and manipulating the level arm). Wheels go back on the ground, and the rear end should now be jacked up by the air system, and as the car comes back down on its own, keep working the suspension until it comes to a full rest. If all goes well, the problem will be fixed.

Suggestion: have the mechanic recount the installation, and find out if he missed a step. Before doing this, I would confirm that installation instructions were included with the shocks. If there was, and you can find them, that can help you as well.

Oh, just noticed I wasn't paying attention, oops.

I suggest jacking up the back of the car, triggering the ELC, and then setting the wheels back on the ground, and then the suspension should settle back down, and be fine. I believe the issue is that when the car was jacked up, the system couldn't draw air in to let the bags expand, so they sucked in on themselves. When the car comes back down, the bag can bind up if in this condition.