+1 This^ If it's lost all its coolant there will be no hot water in the heater matrix hence cold air.Timmyboybunter said:Have you checked the coolant? Very common issue on these is the coolant reservoir getting brittle and cracking.
scootr said:Did the heater blow hot or cold air when the gauge went to the red?
5 minutes is hardly enough time for a motor to cool from hot to cold.
Makes me suspect 2 things. The thermostat may be stuck open (causing no heat) and the sensor bad ?
If the coolant level is correct I think you have to replace the thermostat for starters.
Kevrev said:The thing is its in the red in about 5mins.
ph001 said:Are you now saying it’s going into the red even though coolant is at correct level???
Look for a Leek ?Kevrev said:Checked coolant this morning nothing in there. I checked it 2 weeks ago and it was fine. Going to fill with water start car and look for a leek.
Have you been to Wales recently ? 