Like the others have said, I think the coolant system can “burp” a few times after service like this. Air eventually pushes out and fluid takes its place, coming from the reservoir.
If they did what they said, then I agree they didIn’t likely get air into the AHC system. But also, if they did something wrong, then they probably know how to assert that they couldn’t have done anything wrong. I’m not making any accusations, just saying it’s a possibility.
Now on to the validity of the AHC service…
Ill caveat the entirety of below statements that while they may sound like I’m stating facts, I’m only stating how I understand the AHC system to work.
If all they did was replace the 2 liters of AHC fluid in the reservoir, then like said above they only changed out about half of it at best, and they changed very little of the fluid that’s actually working in the system. Any fluid in the reservoir and any tubes up until the height control valve and the fluid in the accumulator are “inactive” under normal conditions. All the fluid from the height control valves to the “shocks” is constantly active whether lifting or driving.
If you dont refresh fluid through the bleeders then all your really doing is changing out the fluid in the accumulator (which will eventually make it into the system)
Here’s what would happen in the first couple cycles of the suspension:
Put truck in Low - this will push a decent amount of fluid from the four corners back to the reservoir. Maybe a liter?
Change out that fluid. Now you have 2 fresh liters in the tank
Start truck up and raise vehicle from Low-N. Accumulator full of old fluid and some fresh fluid driven by the pump will be pushed into the “active” part of system and raise the truck. Then the pump will push fresh fluid into the accumulator. . So still mostly old fluid in the working part of the system.
So if you do another down and up you will push mostly old fluid back to the reservoir and now your reservoir will probably be about half old fluid and half new… and you’ll have 1 liter-ish new fluid from the accumulator mixing with the 2-3 liters that’s in the system in front of the height control valve..and you accumulator will consist of the half / half ish mix after it fills from the reservoir.
I’m not a chemical or hydraulics engineer.. so I don’t know what the benefits of replacing 1/3rd to 1/2 the fluid in the system is and waiting for it to mix while under pressure in tiny pipes, but I suspect it doesn’t work that great.
I also hope that they verified the fluid they used was good. (Ideally from the metal cans) or from plastic cans that were checked before dumping into your reservoir…
If it was me and I was pretty sure the fluid they used was okay, I’d cycle it up and down a few times and see if it’s better, and just know you probably might want to do a flush at a later date.