Gmwirth

Greetings all. I am new to Hondas, but really like my recent purchase of a black '02 Civic LX. It has a completely rebuilt engine due to a blown head gasket and a warped head. Everything has been running great till the other night on my way home from work when the heater started blowing cold air. The thermostat never budged from normal, engine still purred like a kitten. When I got home, I checked the coolant in the radiator and in the reservoir/overflow and it was all good. No wet passenger floorboard. With other cars I've owned, I've had a similar problems and had to replace blend door actuators. Is this someone that these civics have? Or does anyone have any other suggestions? I have seen many other threads with heater or a/c issues but none the same as this, although I may need one of the same fixes. If anyone has any suggestions they would be greatly appreciated! Thank you!

Wankenstein

Check both levels again when the engine is cold and do so each day for a week.

May end up being the issue. Can you hear the servo motor when you select climate control from max cold to max heat (or vice-versa)?

Check the heater inlet valve (engine bay/firewall) to see if it moves when you adjust climate control from max cold to max heat. Also check all linkage from under dash that connects to the heater inlet valve.

The following link may be related: https://www.civicforums.com/forums/3...r-low-rpm.html
You might want to try bleeding air from coolant system (per service manual).

Gmwirth

Thank you for the great information. I will burp the system today. As for the blend door, there is a definite change when switching between cold and hot, and I don't here clicking or anything when it is switched from cold to hot or vice versa, which is why I didn't immediately jump to that conclusion, just questioned it. It was just odd to me because I was driving down the road with the heater on and it just instantly started blowing cold. I will update later today after I burp the system. Thank you again guys for your input, it is much appreciated!

Wankenstein

Gmwirth

Greetings! Please forgive me for not updating before now. Life and some other issues with the car prevented me from getting back to this thread and this issue. I had the dreaded crank but no start issue. Turns out it was bad plugs. That issue now resolved, I am back to the no heat issue. After burping the coolant system twice, I still have no heat. The heater inlet valve does move when switching from hot to cold or vice versa, The two hoses going to and from the heater core are not hot, nor do they feel like there is anything running through them. The coolant level in the radiator does go up and down when you squeeze those two hoses. I am at a loss as to what the next step would be. I would really to have some heat as it is pretty cold in the mornings here in Southeastern Colorado. Any help would be much appreciated! Thanks!!

Slumpertcivic

Would not surprise me if the previous owner put something like stop leak in when he was having overheating issues and that stuff finally clogged up your heater core.

We are still not sure those lines aren’t just full of air though, might consider disconnecting one and seeing if you can add coolant right in.. if it’s clearly full of coolant then I would disconnect the other heater hose and test for blockage.

ezone

Thermostat good? Top radiator hose gets screaming hot? Temp gauge stands in the middle when warmed up?

Ya, you could disconnect hoses between engine and heater system and use a garden hose to check flow and try to purge out any debris, and

.......inspect operation of that water valve, maybe it broke internally and doesn't actually open and close the passage now even though the lever still gets moved. (manual flow test with the garden hose, or something)

Gmwirth

Thank you for the information and the next things to try. I will get to those this weekend. Right now I am having a repeat of the dreaded crank and no start problem. This is very frustrating as I thought I had the problem solved with new plugs. Im searching all the crank no start threads and gonna spend the weekend working on my Honda. I hope that I can get all these issues resolved as I really like this little car and its perfect for my daily commute which is about 100mi round trip.