Howzit all, im new here and joined up to seek some advice and of course see some great cars! ...... I've recently had my air con re gassed and serviced and that is working a treat again, however, my heater isn't working at all. Had a mechanic have a quick check over near to where i work, he topped up coolant as was a little low and checked all pipes within engine bay to and from heater matrix, he said all seems fine within the bay as the correct pipes were at temperature once car was up to 90 degrees and the coolant levels now correct but still nothing at the vents at all? Could this be an air lock in the matrix? Can i ease the pipe form matrix near to battery that leads into the car, retracting it up past a small pin hole in the connection as I've read elsewhere and release pressure in the system?? Any help and advice would be really appreciated ....🤔