I put some comma air con cleaner through the air con system on saturday.
As instructed leave car on idel for 10 mins with air con on.
Took car out saturday and sunday fine. Today however cars gone into red.
Holding water but heater stopped working only cold air. Then when it came in the temp dropped. Am thinking thermostat proplem any ideas please?

 

would say thermostat but dont know were it is ,change that and see if it works DO NOT DRIVE IT until you have changed it someone will be able to tell you were it is

 

Have you tried getting a air block out ......


let the car warm up with the header tank cap off and slowly squeeze the top and bottom hoses - you may see a air bubble pop worth a try