'95 Civic Cooling Fan not running

[DesignGuy]

I've got a 1995 Civic LX that over the last day or so the temperature gage has been reading high. An inpection under the hood shows that the cooling fan behind the radiator is not running (when engine is hot, so it should be running). In the fuse box under the hood the 15A fuse is good, and when I pulled the fan relay there was 103 ohm across two of the contacts which I assume are the coil contacts. I gave the relay a couple of whacks with a screwdriver handle in case the contacts were stuck but that did not work.

Since replacing the relay is a DIY job and much cheaper than replacing the fan, would it be a good idea to replace the relay or do these "never" go bad and should I just take the car in to have the fan replaced?

It looks like running the AC compressor helps cool the engine somewhat, since the other fan runs, so I'll do that in the interim.

Thanks for any help and advice.

 

[DesignGuy]

I've got a 1995 Civic LX that over the last day or so the temperature gage has been reading high. An inpection under the hood shows that the cooling fan behind the radiator is not running (when engine is hot, so it should be running). In the fuse box under the hood the 15A fuse is good, and when I pulled the fan relay there was 103 ohm across two of the contacts which I assume are the coil contacts. I gave the relay a couple of whacks with a screwdriver handle in case the contacts were stuck but that did not work.

Since replacing the relay is a DIY job and much cheaper than replacing the fan, would it be a good idea to replace the relay or do these "never" go bad and should I just take the car in to have the fan replaced?

It looks like running the AC compressor helps cool the engine somewhat, since the other fan runs, so I'll do that in the interim.

Thanks for any help and advice.

After some inspiration struck me I pulled the fan relay and tested it on a 12V source: the relay clicked and the contacts closed (verified with an ohmmeter). So the fan relay appears to be good.

I then shorted out the relay contacts in the fan relay socket with the engine running, and the fan came on. So the fan is good.

However there was not 12V present at the coil contacts in the fan relay socket, though the engine had cooled down somewhat by this time.

Could it be the thermostat gone bad? Is this a pretty simple fix or does it get too involved for a somewhat technically adept layperson?

 

[TeGGeR®]

I've got a 1995 Civic LX that over the last day or so the temperature gage has been reading high. An inpection under the hood shows that the cooling fan behind the radiator is not running (when engine is hot, so it should be running).

If the engine is anything like that in the previous generation, the fan switch in the water jacket may be bad.

Since yours has a relay, the switch is protected from the full current, but can still go bad. However...see below...

Also, the switch in the previous generation is pretty close to the oil filter and is sometimes broken if the wrong type of filter wrench is used to remove the filter. Yours may be similarly vulnerable.

In the fuse box under the hood the 15A fuse is
good, and when I pulled the fan relay there was 103 ohm across two of the contacts which I assume are the coil contacts. I gave the relay a couple of whacks with a screwdriver handle in case the contacts were stuck but that did not work.

Maybe somebody can post specific instructions on checking the fan relay.

You're not usually looking for specific resistance, but continuity across the correct terminals when testing relays.

Since replacing the relay is a DIY job and much cheaper than replacing the fan, would it be a good idea to replace the relay or do these "never" go bad and should I just take the car in to have the fan replaced?

The fan itself rarely fails.

Remove the switch connector and short the terminals with the ignition on. If the fan then comes on, you've found your culprit.

 

[DesignGuy]

If the engine is anything like that in the previous generation, the fan switch in the water jacket may be bad.

Since yours has a relay, the switch is protected from the full current, but can still go bad. However...see below...

Also, the switch in the previous generation is pretty close to the oil filter and is sometimes broken if the wrong type of filter wrench is used to remove the filter. Yours may be similarly vulnerable.

Maybe somebody can post specific instructions on checking the fan relay.

You're not usually looking for specific resistance, but continuity across the correct terminals when testing relays.

The fan itself rarely fails.

Remove the switch connector and short the terminals with the ignition on. If the fan then comes on, you've found your culprit.

Is the fan switch something I'd have to crawl underneath the car to check? If it's next to the oil filter that sounds like the case. If the fax switch is bad would I *not* have 12V at the fan relay coil contacts in the fan relay socket (because I don't)? I'm not sure of the fan switch location or it's electrical position in the series... if it's like this:

FAN SWITCH > FAN RELAY > FAN

.... then that may be the problem.

On the other hand, if it's like this:

FAN RELAY > FAN SWITCH > FAN

.... then the switch may still be okay, since shorting out the contacts in the fan relay socket caused the fan to start running.

 

[TeGGeR®]

Is the fan switch something I'd have to crawl underneath the car to check? If it's next to the oil filter that sounds like the case. If the fax switch is bad would I *not* have 12V at the fan relay coil contacts in the fan relay socket (because I don't)? I'm not sure of the fan switch location or it's electrical position in the series...
if it's like this:

FAN SWITCH > FAN RELAY > FAN

... then that may be the problem.

On the other hand, if it's like this:

FAN RELAY > FAN SWITCH > FAN

... then the switch may still be okay, since shorting out the contacts in the fan relay socket caused the fan to start running.

I don't know how it's wired, but the fan switch is temperature-operated, closing when it gets hot enough.

If the switch contacts never close, wouldn't the relay fail to get power, and thus never ground the fan and make it come on?

 

[Mike Iglesias]

After some inspiration struck me I pulled the fan relay and tested it on a 12V source: the relay clicked and the contacts closed (verified with an ohmmeter). So the fan relay appears to be good.

Good, because they cost around $40-45 from Honda.

I then shorted out the relay contacts in the fan relay socket with the engine running, and the fan came on. So the fan is good.

However there was not 12V present at the coil contacts in the fan relay socket, though the engine had cooled down somewhat by this time.

Could it be the thermostat gone bad? Is this a pretty simple fix or does it get too involved for a somewhat technically adept layperson?

There's a separate switch for the fan. On my daughter's 95 Civic DX, it was towards the back (passenger compartment side) of the engine on one of the fittings for the radiator hoses, if I remember correctly. You can change it from the top if yours is like hers. The part costs around $45 for the DX.

Her car was having the same problems you are. I replaced the switch, but that didn't help. The relay is good and so is the fan. On her car, it only happens if she drives on the freeway for a while and then hits stop-and-go traffic after she gets off the freeway. I also replaced the thermostat in case it had gone bad and was not opening correctly. It still gets hot occasionally. I may try replacing the relay next, but I can't see paying $45 for a $5-10 part.

 

[Mista Bone]

To test the fan switch, disconnect the 2 pole connector from the switch. It is located in the thermostat housing just below and back of the throttle body.

Turn the key to "run" but don't start the car. Take a 3" piece of 18 gauge wire and stripo 1/4" off each end. Just that wire to jumper the 2 poles on the connector. Fan should run, if so, the relay and everything is OK. Likely the switch is bad OR car is low on coolant!!!!!!!

http://www.bettendorf.com/~mrbone/pictures/Tech/coolant%20wiring.jpg

I wired a switch in parallel of the factory switch so I can control the fan manually OR the factory switch will work. I do alot of drag racing and use the factory fan to cool motor on return road and while sitting in the pits.

Just don't forget and leave it on too long (DUH!).........lucky I can push start my car easily!!!!!!!!

 

[mike (archive)]

After some inspiration struck me I pulled the fan relay and tested it on a 12V source: the relay clicked and the contacts closed (verified with an ohmmeter). So the fan relay appears to be good.

I then shorted out the relay contacts in the fan relay socket with the engine running, and the fan came on. So the fan is good.

However there was not 12V present at the coil contacts in the fan relay socket, though the engine had cooled down somewhat by this time.

With the ignition switch at the run position (IG2), there should *always* be 12 volts present at the coil (black w/yellow trace). If not, check fuse no.13 (7.5 amp) located under the dash. Should be good however, since you mentioned the A/C condenser fan motor to be operational. You might want to re-check and also clean/inspect the relay connector contacts.

The flow for the relay coil circuit is:

Ignition sw (IG2)-->fuse #13 (7.5amp)-->relay coil-->ECT switch-->ground

Could it be the thermostat gone bad? Is this a pretty simple fix or does it get too involved for a somewhat technically adept layperson?

T-stat?? Doubt it. OTOH, the ECT (engine coolant temp) fan switch is another likely suspect. Switch should conduct when coolant reaches between 196--203 degrees, give or take, activating the relay and turning on the fan motor. If you find the relay does indeed have coil voltage, check the ECT switch using Mista Bone's procedure and go from there...HTH

 

[TeGGeR®]

To test the fan switch, disconnect the 2 pole connector from the switch. It is located in the thermostat housing just below and back of the throttle body.

Turn the key to "run" but don't start the car. Take a 3" piece of 18 gauge wire and stripo 1/4" off each end. Just that wire to jumper the 2 poles on the connector. Fan should run, if so, the relay and everything is OK. Likely the switch is bad OR car is low on coolant!!!!!!!

I've got a similar switch near the thermostat housing. It's called a TW switch ("thermo-wax") and does not appear to control the fan unless it works in combination with something else.

Did they move the fan switch from near the oil filter to the thermostat housing for '94+?

 

[Mista Bone]

on the Integraa, yes.

I've got a similar switch near the thermostat housing. It's called a TW switch ("thermo-wax") and does not appear to control the fan unless it works in combination with something else.

Did they move the fan switch from near the oil filter to the thermostat housing for '94+?