Sounds like a thermostat issue. I live in Southern Cali so I just took the thermostat and valve out since over-heating is the problem I would face over the frozen coolant issue the folks in the colder climates worry about.

 

ummm..... NO.



I haven't had time today but now I'll address the issue so this thread will go away...

The fan is controlled by a coolant temp switch. It activates the fan when the coolant is over a certain temperature. You say that you tested the fan on a 40 degree day. Fans often won't cut on with ambient air temps that low.

You have 2 options:

1) Get the coolant hot enough so the switch will activate and turn the fan on.
2) Run continuity and electrical bench testing on the parts in question.


It isn't rocket science, you just have to have a solid understanding of how the parts work in relation to one-another. The fact that you don't know when the fan should be running indicates to me that you're in over your head.

 

In my case we did remove the thermostat, which was my issue, but this isn't your issue and I apolgize for the misinformation. Your issue seems to be with the Coolant Temperature Sensor, which is the part you need to test. This is not a switch as drewmob mentioned, but he was closer than I.

In a 92 accord you don't have a Coolant Temp Switch, but a Sensor or better yet a thermistor which doesn't turn the fan on itself but sends the data your car's Power Control Module (sorta like your cars CPU). Based on the data received the fan is either turned on/off and controls the speed of the fan. The PCM also take into consideration the car's AC when it needs to activate the fan.

Drewmob has a good point that the car might not have reached the temp for the fan to have been justifiably on, however the outside ambient temp is not what this thermistor is measuring but is measuring the coolant temp itself so you might be able to get the car hot enough to see the fan go on.

I'm not sure if the 92 accord is OBDII, if so it would throw code about this sensor being bad and you will see the Check Engine light come on. Try switching leads from the AC fan just to test the fan itself. Otherwise you could just replace the Coolant Temp Sensor and see if that fixes the problem. There is also another sensor which sends data to the dash, which you now say is registering cooler, be careful that this sensor isn't misleading you that the car is running cooler. You might want to replace both, but I think they might be right next to each other. Unfortunately testing a sensor is not nearly as easy as testing a switch since it's not a simple on or off. Good Luck.

 

Moving to Under the Hood...