Wondering if anyone can help me, I recently replaced my heater matrix with the upgraded one that's wider so hopefully won't end up blocked. Followed a youtube video and now have heating working as it should but when I turn the engine off there's a humming noise for a few minutes, also hear liquid moving so guessing its the auxiliary coolant pump but have never noticed it being so noisy before. Tried to add a video of it but file is too large

Managed to cut the video down

All sounds perfectly normal to me.

Thanks mate, probably is and I just haven't noticed before. Can hear a bit better in this video, just seems a lot noisier than before and was like that for about 5 minutes when I really noticed it.

I suggest putting some air conditioning cleaner through the system. My go-to is Autoglym's Air Conditioning cleaner.https://statuscarcare.com/products/autoglym-air-con-cleaner