I have a 2004 volvo s40 1.9t and it has a ticking sound when cold but stops after gets warm, what could be the cause?

check your engine oil and make sure there's enough in there.

lack of oil to lifters, was a common ford thing back in the 80s, when did you last change the oil? sometimes old oil causes the issue, i had a bronco that would start doing it every 4000 miles unless i changed the oil.. try a thinner oil, 5w30, or 5w20..might fix the problem

have vechicle code scanned bad engine coolant temperature sensor will cause vechicle to stall out and hard to crank when cold.

sounds like very low in freon check to see when clicking if compressor clutch is engaging
on and of if so low charged i system usually associated with leak

If it goes tick, tick, tick, you might be low on oil or your lifters may be pecking. It is usually a sign of low oil or engine damage in the block. Check your fluid first. It may be a quart or two low. If not, it will need fixed eventually. That is up to you.

Usually a ticking from the engine is caused by oil not coating the tappets. Tappets are the rods that control the intake and exhaust valves. Once the engine warms up oil is circulated to those parts and the ticking stops.
Mopar is famous for that

evaporator leaking or condensor fan inop

the vehicle is old enough that the fan blower motor sounds like it is in need of replacing. when you hit the dash it causes the brushes in the motor to contact enough to start the electrical connection, it may stop when it gets hot, or is turned off. the ticking sound is more than likely the bearings wore in the motor enough to cause the cage fan to touch the housing enough to cause the sound.

the ticking noise when cold is an exhaust leak.If it is the exhaust manifold gaskets,depending on the vehicle they can be very difficult to replace.in some cases you must remove many other parts even to see the manifolds.make sure when manifolds are off that they are checked for warpage,this is a simple test needing only a straight edge and feeler gague.ask your tech if he can see any broken manifold studs/bolts and if quote covers time for removing broken manifold studs/bolts,because if any are broken,this can take quite some time to extract the broken studs/bolts.

does it go tick tick tick tick and when it warms up it stops or goes quiet?
its your lifters not getting enough oil
when u change your oil it will stop till that oil gets worn out
you will have to replace the lifters or it can also be a slack oil pump not pumping oil around the engine like it should