backlaboy

1999 Civic VP AT

Everyone tells me the radiator fan should cycle on/off with the AC fan. Is that true?

Electrical diagram shows that pin 26 of connector A on the ECU should pull to GND thus energizing the coil of the radiator fan relay making it turn on.

However, manual states connector A pin 26 to the ECU is the fan control (FANC) but when I look at the diagram of connector A pin 26 it shows (PSPSW) and (FANC) is pin 20. Could the manual be worng? Typo? What is (PSPSW)?

I am thinking the ECU is bad. Radiator fan works fine otherwise when the temp goes up. Any thoughts of why it doesn'

t cycle on/off with ?

ezone

Radiator and condenser are completely separate and independent on a 99. Correct?



Therefore the rad fan should only run when the engine temp turns it on.
Condenser fan should always come on when compressor clutch is engaged

backlaboy

Yes, they are separate fans and circuits. However the radiator fan is temp controlled by the Engine Coolant Temperature Switch and by the ECU. Both circuits can be seen in the electrical diagram I attached. Many people tell me the ECU will turn the radiator fan on when the AC fan is on but it doesn't on my car. Thus I suspect the ECU is bad.

ezone

Stop. Not the fans.

The radiator and the condenser are completely separate and independent.
Each has its own separate fan and its own independent fan control.



The fans are controlled independently. They do not have to run at the same time. No problem. ECM has nothing to do with this. ECM is fine.






Also, you only showed part of a wiring diagram. Not enough.
Fan circuit to the ECM may only be an input, not a controlled output.