My civic 2002 heater and a/c system is not blowing hot air or cold air. . Recently the engine has been replaced. After being replaced, I stopped getting cold air from the A/C. I was told that the compressor automatically shuts down if the freon is out. Is that something to consider with the A/C

Where would I start to diagnose the heater system? The blower and control systems all seem to work fine. Coolant levels are good.

 

You may have a clogged heater core, and unless you had the A/C system recharged... its not going to work either.

 

Can I just flush out the heater core with a water hose. I felt the heat on the hose going to the heater, will a clog reduce heat? And, will I detect debris in my coolant?