2005 Rocam. When aircon turned on, why does engine temperature increase to max?

Question edited for clarity and translated from Australian :>D
Question moved from AC Cars, maker of the

AC Cobra GT Roadster

to Ford Bantam 1.6.

That isn't the way you do it. You replace the AC pump with a Bypass pulley, and then the belt and the routing reman the same.

https://www.google.com/search?q=2005+Ford+Bantam+1.6+XLT+Rocam+AC+Bypass+pulley

..

Have you replaced the thermostat that controls the coolant flow to the radiator? These are a common part that fail and cause over heating issues. They are usually reasonably cheap to buy because of this. I think on the Rocam you replace the entire thermostat housing, the housing includes the new thermostat and a new water temperature sensor so that will be another part updated without any extra work.
The easiest way to find the thermostat housing is to find the large black rubber hose that comes out of the Top corner of the radiator and follow it back to the engine block. The hose should be clamped to the housing at the opposite end of that hose.
Once you have drained the coolant and removed the hoses at the housing end you can reach in and remove the 6 bolts holding the housing to the engine. I think they are either an 8mm or 10mm bolt head. There is a smaller hose on the lower side of the housing but this is easier to remove with the housing off. Refit the smaller hose to the new housing. Before tightening the clamp for that hose hold the housing in it's position on the engine and check the hose isn't twisted and positioned correctly, Then gently ease the housing to one side so you can tighten the clamp.
Position the thermostat housing onto the engine and using your fingers screw the bolts in as far as you can. Then just using the socket and a short extension bar like a screwdriver again tighten the bolt as best you can. Finally use the ratchet to finish off tightening. Each bolt should only move less than Half a turn before it feels tight. That's as tight as they need to be. Refit the larger hose and tighten the clamp to make it water tight.
I find if you mix your fresh coolant in a separate, clean, watering can it's easier to get the 'half and half' mixture correct. One bottle of coolant followed by one bottle of fresh water poured out of the same bottle the coolant was in. Fill the coolant tank to on or just below the "Max" level and no higher as the coolant level does change as the engine works and needs somewhere to escape to.
Now you need to 'Burp' the system. Start the engine and let it idle up to working temperature, about 10 minutes. This allows the coolant to heat up and trigger the thermostat to open. Turn the engine off and check your coolant level. It should have dropped. Top up the coolant to the MAX mark and drive as normal.
Over the next 2 or 3 days keep checking the coolant level. It shouldn't change but if it does it won't be by very much. Again top up to the MAX mark and NO HIGHER if it needs it and that's the job done.

When you replace the fans do you validate that it runs when you switch on the aircon? some cars have alternating relay system that when one of it fails the fan will work when engine is hot but will not work when aircon is on. If all the engine cooling system and cooling fan electricals are fine then you may have to get your aircon system serviced. Particularly the radiator in front of the coolant radiator.

If the temperature gauge is not showing an overheating engine I would guess that either the sensor is wrong or the thermostat is stuck open. Stuck open is not as bad as stuck shut but it would mean that your car will struggle to get up to temperature. Stuck open will also increase engine wear and stop the heater working effectively. A stuck shut thermostat will stop the cooling system from working and cause overheating which potentially will destroy your engine.

Yes the fan should stop if the temp gets to cold , a good temp to run is 180--190 deg F.

Motor produces heat from the combustion cycle which warms up the coolant which the thermostat restricts the flow of to the radiator until the coolant gets to temperature then it opens and allows the cooling system to keep it at the optimum temperature for effective operation hopefully
you tube has video's of thermostat testing

are you referring to the engine temperature overheating or the cabin temp not cooling down with the aircon on? I am struggling to think of a reason why operating the aircon would affect engine temperature

if engine over heating coolant over flow jug will boil over you will see steam.sound like you have either faulty engine coolant temperature sensor or could have faulty fans relay or fuse or pcm problem if coolant fans dont turn on.have garage with code scanner that can do a snap shot on coolant temperature sensor check see how hot coolant temperature is see if coolant temperature over 220 degrees engine getting too hot.could have faulty water or blowed head gasket check engine oil on oil dip stick look milkly you have blowed head gasket. i use infra red laser thermometor check see how hot engine is over 107 celsius engine is overheating.

Full coolant level does not mean your engine cannot overheat. You need to fix the problem as overheating will destroy the engine if not addressed.

The radiator cooling fans must be working, as must the water pump. The thermostat must also be working properly.
There must also be no air in the cooling system as air locks will impair water flow. When cooling systems are drained fully or partially and re-filled air in the system must be bled out using the correct bleeding procedure for the particular engine/cooling system. Failure to do this properly will lead to overheating.

If you ONLY see the overheating warning when running your aircon you need to check that the electric radaitor fans are kicking in at idle when you switch on and run the aircon and the engine has been warmed up some. If they do not start operating when the a/c is running you will get an overheating condition in normal driving conditions.

If the radiator fans are operating normally and you still get an overheating warning when the aircon is on or off the most likely culprit is a faulty thermostat in the engine's cooling system which will need to be replaced.

If you have either a faulty thermostat or if the water pump in the cooling system fails you will get continuous overheating whether the aircon is on or off.

P0128 is Coolant Thermostat ( Coolant Temp Below Thermostat Regulating Temperature ). The thermostat may be stuck open, preventing normal operating Temperature from beeing reached.How is the heat inside the car is it below normal ? Or the engine Coolant Temperature Sensor may be faulty and needs to be replaced. Good Luck and have a good XMASS.