After looking through several threads, I still have an unanswered question concerning sensors/switches on the cooling system of my 93 Accord LX M/T.

I have two visible 2 wire connector type sensors which seem to be identical.

1) One of them is one the thermostat housing between the block and the firewall. This harness is difficult to tell exactly where it is going, but appears to go down toward the passenger fender well and toward the front, and assumably connects to the fan on the radiator.

2) The other is located on the other water housing for the upper hose to the radiator. Its pigtail is obvious and visibly contained in the same loom as the pigtail for the O2 sensor. I'm would think this would be the sensor for the ECU fuel management stuff.

On visual inspection of the two sensors, they appear to be identical, and although I have a repacement for one, this replacement takes a 19mm and the existing two sensors are 24mm. ( at least the one on the upper hose on the front of the motor is confirmed 24mm, didn't physically check the t-stat housing sensor, but it appears to be the exact sensor as the other existing one.)

So, do they have a mix match of sensor sizes or types for these applications?

I haven't removed either of them, because I honestly don't believe the one replacement I do have, would fit either location. Just comparing it closely to the existing two sensors, it appears to be smaller in diameter than them.

I also seem to notice the terminology for these sensors is kinda 'loose', I'm not sure exactly which either of them is officially referred to, but I do understand the difference in there application.

Hope all that makes sense and is complete? and thanks for any input!

 

I think in '93 those are both radiator-fan switches. The one in the thermostat housing is responsible for switching the fan while the engine is running. The one in the upper radiator hose nozzle is responsible for switching the fan after the engine is shut off. They have different temperature setpoints. They're called fan-switch-A & fan-switch-B but I can't remember which is which.

There should be ANOTHER one screwed directly into the head, somewhere near or below the distributor. THAT one is the water-temperature sensor for the ECU.

Use a multimeter to measure the resistance between the 2 terminals of your new sensor. If it's a fan switch it should measure as an open-circuit because it's really just a switch turned off. But I'm guessing it's gonna have some measurable resistance because it's the sensor for the ECU.

Incidentally, there's also another sensor nearby. It's only got one wire. That one is the sender for the dashboard temperature gauge.

 

Thanks, that's helpful indeed.

I knew about the single post sensor for the temp gauge in the dash, didn't realize there was another one by the dist.

I'm gonna try to put my eyeballs on it, I'm thinking it should be slightly smaller in diameter than the fan switches.

I also have a DMM, so I'll see what it reads...