Low speed cooling fan random issue

[Speedwell87]

Hi, I’m hoping someone can help! At the start of lockdown the start stop battery went completely flat after 2 weeks sat doing nothing. As everything was closed, and I could not get help from my dad due to social distancing, I bump started the car, battery was completely dead as it had a meltdown. Chugging, couldn’t rev engine, lights flashing, engine malfunction displayed. Turned off and back on again and all resolved. New battery put in, all error codes cleared. Never had a problem with the car at all. Since this incident, the cooling fan only kicks in at high speed (a neighbor described it sounding like a hairdryer coming down the street). With aircon on, it used to before be on constant at a quieter speed, now it kicks in and out, and when getting hot it sounds like it’s working overtime to cool engine down. Checked fuses and relays, all ok. Anyone experienced this? My local garage says it’s normal, but I know my car, and it’s not how it used to be! I have been told resistor, but not sure this part comes separately, or control module, but can’t see one on fan.