Engine getting very hot

Good morning all,my wife has a 2006 c3 desire and she is a community carer so uses her car every day to visit the elderly in there own homes.
The car up until now has been working fine but on Thursday evening when she stopped at a clients house when she got out there was a strong smell coming from the engine area.
She opened the bonnet and found that the engine felt really hot but there had been no warning lights on the dashboard or had the level of coolant changed in the coolant reservoir.
I then arrived 50 minutes later and to me there was still a strong smell coming from the engine area which did to me smell a little like it a clut h smell but my wife said that the clutch is good as usual, but she did say while she was driving at no time had she heard the engine come on to cool the engine down.
The car seams ro be running OK at the moment but she is concerned due to the fact she relies on her car daily to take care of the elderly clients she visits.

So the question is what could be the obvious causes.

Many thanks in advance.

First up you need to determine if the engine is actually over heating.

You can test the engine temperature circuit by removing the green electrical connector from the sensor. The sensor is located on the top of the thermostat housing, where the 'top' radiator hose exits the cylinder head.
With the engine running disconnect the sensor and after a few seconds the thermo fan should begin to run at full speed and the engine coolant over heat light on the dash should come on.
If the fan and light come on you will know that, in an over heat condition, the fan will run and the driver will have a warning. This may not stop an over heat but you will be warned!
I would find it difficult to qualify if BOTH the dash light AND thermo fan did not come on! When the green connector is removed SOMETHING should happen!
IF you can establish that the cooling system is working, then if the fan and/or lamp did not come on (when driving around) then you can assume that there was no over heat condition. This is not conclusive proof but the temp sensors tend to fail in an open circuit condition (like pulling the plug).
The probability that the electrical circuit AND the engine coolant circuit have failed at the same time is unlikely!

If you recognize the smell of burning clutch material it still might be that, or it might be a dragging brake pad?
The smell of hot coolant, hot metal, brakes/clutch, auto transmission fluid, petrol, burning oil, brake fluid, all have distinctive odors! If it smells like brake/clutch pad then that's probable what it was!

Many thanks for your reply,my wife has continued to drive the car since the initial problem on Thursday evening.
She said the car has been ok apart from it still getting a little hot,no dashboard lights or fan coming on so I was wondering if the problem was with a faulty thermostat, perhaps partially blocked or only opening slightly so will check that and also the water pump too.

Many thanks for your help.

This is one thing I do not like about some modern cars...lack of a temperature gauge.
Unfortunately you are at the mercy of a little light bulb to tell you that your engine is/is not over heating!

Thermostats tend fail open or closed. Not typically in between. If they fail open, the engine takes forever to warm up and tends to run cold.
If it fails closed, the engine will quickly over heat and your little temp light will come on.
A partially blocked radiator tends to cause over heats at high speed but engine is OK around town.
Could be under performing water pump. Bad coolant can damage or "eat up" the impeller fins.
Engine coolant outlet temp for a normal engine is 90'C. 100'C is max "normal" condition. Warning lamp comes on over 105'C. 120'C is over heat and "stop the car now" warning!! So you can see there is only 30'C between normal and the "you've just caused damage to your engine" lamp.

I would pull the green plug and at least make sure the warning system is working.

Many thanks,will do that.

Cheers