2019 Volvo vnl AC has been acting up not blowing forcefully

Did the mech evacuate the system and check that it holds?
Also if your radiator is overheating, it effects the condenser, which is it's neighbor.

 

Pics are your low side lines sweating.
Take a shop rag or something similar and see if it will stick to the condenser with the engine fan on.

 

You say it's not blowing forcefully, and it's not cold.

Is it both? Having to shut it off, idling, or just turning it off for a while sounds like it's thawing out. If that were the case, it's freezing up either because it's low on freon, not moving enough air across the evaporator, or a thermostatic switch not killing power to the clutch at a certain temp.

It sounds like you're saying in hard pulls it's actually not putting out the same volume of air from the vents. Is that right?

Hard to imagine anything in a pull that could cause that.

 

Do you have a clogged cabin filter? If it’s blowing weaker as your speeds lower that means less air is being forced in to your cab.

 

I am just a driver, not a mechanic. Recently had very similar symptoms on a 2020 Cascadia day cab, sans the mtn part. My symptoms were anytime I had more than 42k in the box (something to do with the engine fan). Shut the a/c system down for 15-20 minutes and it started working fine again.

According to the terminal mechanic the problem was a sensor that prevents it from getting too cold. He indicated that the evaporator was getting so cold that a film of ice formed, then air could not pass thru. Shut the a/c off for a bit, the ice melts and it works again.

In any event, whatever he did cured my woes. Best of luck with it.

 

How long have you had this truck? If you aren't familiar with Volvos they go through a blower motor every few years. If you haven't ever put a blower motor in it I would do this regardless, because it's going to go out soon.

 

If it's low on freon. the air out the vents is warm.

Nothing is getting cold with low freon. Or the system wouldn't need as much as it does.

 

Clean your condenser and ACA, maybe even the radiator. This is a safety feature of all trucks when the condenser can’t get enough flow the ac compressor is disengaged to keep the system cooled under a load, when the threshold is lowered, that means the system is not cooling and is plugged.