header tank

do not quite understand your question can you tell me what the problem is? just tell me as best you can.

pressure in header tank coolant coming out off cap blowing cold air from heater.

first thing to do is change the thermostat and bleed the cooling system, then get a cooling system pressure test done to look for any external leaks. there will be air trapped in the cooling system.has any work been done on the cooling system recently?

yes, this has all been done with the same outcome.

okay, you need to get a head check done. this is a quick and simple chemical test to check for Co in the cooling system. also, make sure that the radiator is not blocked get it removed and core cleaned a back flush will not be enough and also flush and check the flow through the heater core as well.

thanks for all your help.

ok, no problems, re post if you have further questions or problems