I have a 99 Civic HX and the heat is not working in it. It blows air out but it doesn't get hot or even change temperature. It is full of coolant, I flushed the heater core, and changed the thermostat but it still doesn't get hot. I noticed that the heater contol cable that opens and closes the heater valve on the firewall doesn't move when you adjust the heat from hot to cold. I took the cable off and adjusted to the valve manually making it fully open and fully close but the air still didn't change temperature. Now I am all out of ideas so if anyone could help I would really appreciate it. Thanks.

 

First thing to do is confirm valve is opening, you will have to remove it to do so.

You can also try bleeding the coolant system, you may have air in it, air trapped in the heater core will prevent coolant flow through the heater core.

We change 3-4 "water valve" on Honda/Acura every year, most of them will have working levers, but the valve itself is not working, so pull yours and confirm it works. 94

 

my 95 sol had the same problem, i was lucky to only have air pockets in my cooling system

thank god

 

When I flushed the heater core I sprayed water through the heater valve and it came out the other hose so it must be open unless it closed when I reconnected the hoses. I won't be able to check it until this weekend because its dark when I get off work. I'll try bleeding the coolant system too. Thanks for your help

 

I am new to this so please be kind. I have a 1992 Civic. The blower works fine but only blows cold air. Can you give more specific instructions on how to check and see if the valve is opening? If it is not, does that indicate that it will need replaced? Are they expensive? I appreciate any help you can provide.