Cooling fans do not come on

maxx · Post by **maxx** » May 1st, 2006, 11:05 am

Car: 1993 Mazda MX-3 1.6 liter 4 cylinder

Pulled the check engine light codes for my car, the only one I got was for the water thermosensor. Replaced that and after idling for a while (idled beautifully, unlike before), I noticed the cooling fans never kicked on. They didn't prior to the water thermosensor replacement either.

The thermostat in the car never moved over 50%, after the thermosensor replacement it read more accurately and after idling it read as just below the tick before hot.

I shut the car off. I disconnected the fan connector (for the passenger side cooling fan) and ran a hot and ground, the fan ran (so the fan motor itself isn't bad). Next I traced the wires to the fan relay, disconnected the relays (two of them) and ran a hot and ground to the same fan motor, it work, so I know the wires/connection from the relay to the wire connector is good.

Where would you go from there?

From the wiring schematic in the chilton's manual, there appears to be two fuses that pre-relays. I am unable to find either fuses (if they exist).

What sensor(s) does the fan relay work off of?

I'm going to continue to work on it later today, just wanted any advice.

Limegreen mx-3 · Post by **Limegreen mx-3** » May 1st, 2006, 3:39 pm

the senser u replaced was it the one thats mounted on the therestat housing. that senser controlls the cooling fan.

ariesdude · Post by **ariesdude** » May 1st, 2006, 4:38 pm

I had a similar problem on 94 DOHC - it turned out that the connector close to the fan was corroded and had intermittent connection - so when i moved the wires to test them it will work - but when i connect them to the fan wires it wont work. Finally ended up getting a small brass brush and then cleaned the heck out of the connectors and it worked fine for a while. It corroded again in a few weeks - so i bypassed the connector - and tied the ground wire to the frame - it has been working fine since then.

maxx · Post by **maxx** » May 1st, 2006, 7:40 pm

The sensor was located between the intake and the valve cover.

It doesn't appear corrosion would be the issue. I tested at the connect closest to the fan and at the relay with a straight connection to the battery and it work.

The issue would have to be from the relays back.

Grants · Post by **Grants** » May 2nd, 2006, 12:51 am

Have a look here at Figure 7, grid A27.
http://eunos30x.com/info/1993%20Wiring%20Diagrams.pdf

So the weak points:
- the fuse in the engine bay (just swap it)
- the "coolant thermo switch". Short that BLACK / GREEN wire to ground and the fans should come on. (Engine running)

maxx · Post by **maxx** » May 3rd, 2006, 11:09 am

Thank you Grants.

I grounded the black/green wire that connects to the coolant temperature sender with the car on and the fans work.

I will be picking the coolant temperature sensor up today.

maxx · Post by **maxx** » May 3rd, 2006, 2:01 pm

I just went to my local autoparts store.

I asked for a coolant thermo switch, they handed me the water thermo switch (what I originally replaced, biggest different is the water thermo switch has two blades and the coolant thermo switch has a single blade), I said that wasn't the part.

I asked if they could find a coolant temperature sensor/sender, they told me it was the sensor they originally gave me (water thermo sensor).

Is there anything else this switch can be referred to as?

The Chilton's manual states it's the Coolant Temperature Sensor, then later refers to it as the Coolant Temperature Sender. The pdf above refers to it as the Coolant Thermo Switch.

I am going to pull it out tonight and goto another parts store (same as before, different location (the location I would normally go to)) and see if they can find it.

The funny thing is, I originally bought the water thermo sensor from them, went back to the same guy and asked for the coolant thermo switch, and he said they didn't have it but the other shop (the one I just went to) did.

Oh well, good luck to me to find some place that sells it.

ariesdude · Post by **ariesdude** » May 3rd, 2006, 2:46 pm

Is it one of these...

http://www.rockauto.com/catalog/catalog ... ttype=5100

http://www.rockauto.com/catalog/catalog ... ttype=2188

http://www.rockauto.com/catalog/catalog ... ineID=3442

Try asking for the part number - usually they can find it easily with the part number.

maxx · Post by **maxx** » May 3rd, 2006, 4:03 pm

It looks most like the first link you sent.

I will be pulling the part tonight, hopefully I can find a part number on it.

I will update later tonight or tomorrow hopefully.

Thank you

maxx · Post by **maxx** » May 3rd, 2006, 11:38 pm

I went back to the local auto parts store and they were able to find the part (after much searching).

The guy who found the part said it was called the Cooling Fan Switch (in case that helps anyone in future searches).

I want to thank everyone who helped.

lennyseleven · Post by **lennyseleven** » August 13th, 2006, 5:56 pm

Did replacing the cooling fan switch solve the problem? WHere is it located?

thanks