T4 behaving differently

[M88JCP]

Evening all

I'm after some more advice please?

Lately I have noticed that my cooling fan is coming on every time the car is used. If i drive for more than 5 minutes the cooling fan is coming on, staying on for a few minutes, stopping and then coming back on. If i stop the car and turn off the ignition, the cooling fan turns off, but if i turn the ignition back on, the fan will restart for a minute or so. Is this normal and just a result of this weather? I have recently replaced my thermostat (genuine Volvo) and replaced my coolant with Prestone ready to use. The temperature gauge goes to half way very quickly from cold, and hasn't gone above this, even is slow traffic.

Also, with the latest heatwave I have started to use my aircon, normally i just open the windows and sunroof!! I have noticed that when i turn my aircon on, the ECC kicks out ice cold air, but my engine starts to idle erratically and the car feels like it surges in power when driving at speed. When i turn my A/C back off, the car returns to running normally.

Does anybody have any thoughts on this as i'm getting abit worried by it!!

Thanks as always
James