Friends... two months ago... while searching out coolant leaks...I had mechanic bypass heater... located coolant loss at throttle body heater and corrected... winter came... had heater hoses hooked back up... NO HEAT... mechanic has hoses reversed from diagram... bleeding etc does no good...heater blows cold... would hoses being reversed cause this? Mechanic is now wanting to flush heater core.... please respond... warm here for three days... hope to fix before winter returns!
BTW... no over heating issues and gauge actually showing tiny bit cooler than I was used to ..and car running noticeably better
just attempted heater core flush... would not accept water from EITHER direction....HELP!!

 

If the core won't accept water, it's clogged. You can try some white wine vinegar, water, and compressed air to free it up.