No hot air from AC

I've recently bought a Fiesta that has sat for a while and previous owner apparently never used AC.
I've gotten the system regassed, the front radiator had been replaced recently.
But I get no hot air from the system when AC is on, ive tested that I get cold air coming out and all the blowers push out air so not an issue there just no heated air?
The front radiator fan is really loud either when I've been driving for a bit and stopped or turning AC on the fan is super loud.
Supposedly it was a missing fuse for heater but all fuses are installed according to the fuse box and what this car can take(still need to test them all)

Any ideas?

The fan shouldn't be loud. Whoever replaced the radiator may have messed something up. I'd start with the fan and go from there.

And...
With AC on, it is designed to cool the air, so unless you run Heat on the temperature knob or the Defrost setting with Heat - you don't get Hot air, you get temperate (air that's been dried and conditioned) air.

So if you run with AC on, you don't get Hot air - it's for drying (less humidity) and then reheating air to a comfortable level of heat to warm up the air in the car - it's really to help you reduce fogging from higher humidity condensing on the windows and helps keep your windows clear from fog to help your driving.

When it's Cold Outside and you want heater...
When you're not getting HOT air - when you turn on the knob to any setting and only have the Temperature knob to HEAT - hard over - as in all the way to heat - and you're not getting hot air - have someone help you to locate and remove the cover to the CABIN AIR Filter - remove the filter and see if you can start the car and operate the heater setting see how the heater side works now.

If you have heat now, the Cabin Filter was blocking a vane from letting the Heater Core blow hot and not mix air with cold air. You can replace the filter with a new one and put it in there properly so it can provide both heat and cool. But, if it still doesn't work, then you'll have to take it to the shop to have them investigate and fix it or you can try and track this down yourself and locate the various actuators and motors that move the drum and valves to blow hot or cold air to the various vents and look for and replace those that are not working when you turn the big main knob to the various settings and watch the operation.

@Handy Andy @econoboxrocks
So update from earlier I saw on some other forums to try max fan and bits but this didn't work although when I tried max front screen this worked to get heat through and I could adjust it although when I turned the temp down to cold I couldn't get it back to hot without turning off and doing max front screen again.

@Handy Andy
I've recently replaced cabin filter(after the issue was present)

With the fact I can get hot but only when turning on the front defroster, does this mean the flaps/vanes?