Should booster pump be pushing water features during freeze protection?

Check the pump lid to make sure that the seal is clean and lubricated.

listen closely to the lid as the pump is turned on and off to see if you can hear any type of air leak.

There are tire tracks near the equipment and it looks like a valve handle is missing.

Maybe someone drove something too close to the equipment and broke a valve and caused an air leak?

It should still prime though because the leak would be on the return side.

I would guess maybe a bad lid seal from dirt or maybe the O-ring fell out.

If the lid seal is good, maybe open the check valve in from of the pump to see if there is anything stuck in the valve.

Why is there a check valve in front of the pump?

Is the pump a lot higher than the pool?

If not, I would remove the flapper.

If you really want a check valve, then I would put one on the pump output and not the suction.

Also, a WhisperFlo pump is a bad choice for a water feature pump because a WhisperFlo pump is a high head pump and water features are low head applications.

An IntelliFlo VSF or a water feature pump would be a better choice.

If there is a steady trickle of water, try leaving it on for a few minutes to see if it catches prime.

If there is no trickle, don't leave it running.

Is the pump above the pool?

If yes, by how much?

Sorry, my post didn't make sense. Deleted.