Hello please let me know if this has been covered and if so a link would be great. I have a 2001 Civic Lx I just changed the water pump, timing belt, tensor, and oil pan gasket. I put in a new thermostat, cooling fan switch, and ECT sensor, all Honda parts from Honda parts.com. The first issue is the fans aren’t coming on if I jump the cooling fan switch the fans work great, plugged in to switch nothing, (I checked for continuity and it is good from relay to fans, and from the ground, locations 201, and 301). The second issue burped the system twice, and when I run the car for an hour the upper radiator hose is hot but the bottom is cool, and the radiator is not warm or hot. However, there is hot air coming out in any selection in the cabin, and the temp indicator is below halfway. The coolant is hot, and I replaced the radiator cap, also the coolant is blue with no oil in it, and when I checked the oil, it is not milky or white. And there is no indication of a blown head gasket. Could this be a partially clogged radiator? -TIA

 

Believe the temperature gauge.
The top hose should be hot and as the water cools in the radiator, it falls and comes out the lower hose cool.
Take it out for a drive and watch the temp gauge.
Mine stays a bit less than 1/2 and is steady as a rock.
My 01 Civic will run a lot with the fans never coming on unless it is hot out.
These small 4 bangers make little heat but will keep you warm in the winter time because of the thermostat.

 

The coolant sensor by the thermostat runs the fans , there's a sending unit on top of the motor that runs the temp. gauge . Sounds like there's still an air pocket . If you remove the small hose above the thermostat and put a clear length of hose on that nipple and run it into a jug of coolant mix , The stock hose goes into the jug also and will draw coolant , the hose on the nipple will push coolant . You should see a good amount of air come out .I had problems with after market thermostats and only buy honda OEM .