A while ago, my radiator fluid levels started getting low and I noticed my radiator fans weren't coming on. I had a garage diagnose the issue and they replaced my whole radiator/cooling system (This was before I realized how easy it was to DIY).

Time went by and I noticed my coolant level was getting low again and I thought it was normal so I just added to the reservoir. Since I paid a decent garage to take care of everything within the last 18~ months, I took for granted that the system was working including the fans, but in retrospect my fans weren't working. Soon after I noticed the smell of coolant followed by seeing a coolant mess from the radiator that had blown

I ordered a new radiator and installed it along with a new thermostat and temp sensor (that goes on top of the engine block). I did not replace the fan switch sensor because I tested it in boiling water and it worked.

I made sure the bleed the system and even got the "tall funnel," but the fan won't come on and there is steam coming from the radiator neck after enough time. The dash temp gauge was not showing any overheating, but it did take a while to get to temp sitting at idle (it's winter).

To test the fans and the wiring I tested the relay with the battery, i tested the connections in the relay box, i tested the fuse, and I tested the wiring to the connector by jumping the pins. In all of these cases, the fans came on when the car was in ignition II position.

I took the car to MIDAS and paid them for diagnosis, since they always charge me for a diagnosis even if I bring in there for a known issue. According to their computer, the temp was reading -40 and he said he would need.to replace the fan switch temp to proceed with diagnosis

I took the car home and installed a new fan switch sensor, and the fans still don't come on. Today, I replaced the connector that goes to the fan switch sensor and the fans still don't come on. I even verified that the continuity of the new connector wiring to the pins was not reversed for some reason

I cannot think of what would be causing the fans not to come on. The bottom radiator hose is staying cold, but the top one gets warm. The heater blows hot. I don't see any check engine codes indicating a stuck thermostat. I did remove the AC condenser coils since they were broken anyway, so the A/C pressure switch is probably no engaging which means the fans don't come on when I turn on the AC. From looking at the schematic of the wiring, the radiator fan switch on appears to be independent to the AC compressor pressure switch that may be stopping the fans from coming on with the A.C. The next thing I will test is jumping that connector, trying to make the fans come on with the A/C and then seeing if that somehow affects the behavior of the radiator fan switch circuit.

I have heard claims that "only honda sensors" are good, but I am not sure which brand these would be (other than denso) and Im not sure why they would be misbehaving.

To summarize, at this date i've replaced: Both fan switch sensor and temp sensor on engine block, radiator, thermostat, connector to fan switch,

Thanks,

D Cycle