We have a very interesting problem. We have a Honda Civic, 1994, CX, 1.5 engine. The original problem was that the car overheated. We noticed the radiator return hose and heater hoses were cold while the output hose was hot. Also the engine coolant fan would not come on. We changed out the Thermostat and now the engine still gets very hot, the heater doesn't work (doesn't blow hot air) and when the heater fan is running at any speed the car runs good. But, when the fan is turned off the car starts missing. Would appreciate any help in this are. Thanks in advance.

 

Did you check to see that the heater valve moves when you slide the temperature control? It is cable drawn.

Your fan may have a faulty switch or bad relay. The switch is next to the thermostat and costs $35 or so at NAPA, but I have not been able to find the relay anywhere. To troubleshoot whether the fan is working or not, you need to find a way to hook it up directly to the battery (probably using jump wires) to see if it turns on or not.

The car should not be missing, obviously. It may have an electrical fault somewhere in the system.

 

It is obvious the coolant isn't going anywhere if the return hose is cold. So are you saying now that you changed the thermostat that the hoses are now warm?

 

try flushing the cooling system. some napa thermostats just are plain out sh*t. good way to check is fill a pan full of water and heat it up to 300+ degrees on the stove and pop the cold thermostate in it and watch it open

 

The return hose is still cold and the engine cooling fan now works. The car still misses prior to overheating.
Oh, and the thermostat works just fine.