1995 Honda Civic Lx 1.5 cooling fan

The radiator fan on a 1995 Honda Civic I bought a few weeks ago
does not come on. I have changed a defective thermoswitch and
the new one turns on in boiling water, also replaced the thermostat
(the old one was only opening about 1/3),, flushed the radiator
and ran the engine for nearly an hour at idle. the temperature went
up to about midscale, never even close to red line. The upper hose
was very hot and lower hose was not too hot to hold. The new thermostat
opens in boiling water. I drained the flush water, it was
hot but no where near boiling. How hot does that thermoswitch
get before it turns on. I have checked the two wires going into
the thermoswitch and there is infinte resisance(key on, engine not
running) also put new relay in fuse box(Old one was missing)
and fuses too.
Do these cars run super hot or have I missed something?
Ernie

 

Pull the connector off the thermoswitch and short the pins on the
connector together. Turn on the ignition and see if the fan comes on.
If not, you'll have to figure out why (bad fan, wiring issue, relay
not working, etc).

 

Thanks Mike, I was hopeing Honda had hidden a fuse
that I didn't kmow about.
Ernie

 

I think the AC fan relay and the radiator relay are the same partnumber
(check the PNs, to be sure).

You could just temporarily swap the relays until you get around to
getting the relay from your favorite mail order place (mail older being
cheaper than your local dealer). Just don't run your AC until you get
the replacement relay.


Regards,
Remco

 

Thanks Remco,you are right, the three relays in the
underhood fuse box are the same. I tried Mike's suggestion
to short out the plug to the thermoswitch but nothing happoned.
I had previously tested the fan moter and it worked.
Have also tested the green wire from the thermoswitch back
to the relay and got a solid wire reading with one wire
on the relay. I even swapped relays with the new one I had
installed. I may just have to shoot it or take it to Honda
Thanks again
Ernie

 

Hi Ernie

Well, at least you narrowed it down to it not being the thermoswitch or
relay. I'd try to troubleshoot it, because there are not an awful lot
of connections in the circuit. Honda will just charge you an arm and a
leg for what might just be a bad connection.

When you unplug the relay, make sure you have 12V on one leg of the
coil and also 12V on one leg of the contact. Both these connections are
tied to separate fuses (the coil's supply seems to go to the underhood
fuse box, the contact seems to go to the under dash fuse box).

If you see 12V on both these points, determine if shorting the contact
side of the relay will turn the fan on. If not, trace the wire to the
fan -- it may be bad or broken and also do what's below regarding
checking the fan.

(---checking the thermo sensor leg)
If so, the problem must be on the side to the thermo sensor. With the
engine cool, you should see 12V on one side of the thermo switch (it is
not directly tied to 12V but goes through the relay's coil). The other
side of the thermo sensor should be tied to ground. If you don't see
12V on one side of the sensor, the schematic shows that a junction
connector exists going to the relay and the ECM -- that connection
might be bad.
If you don't see ground on the thermosensor, trace that wire back to
its origin -- that connection should be a ground and must be loose.
You could actually try tying a ground wire to the wire that measures
12V on the thermosensor -- that should turn the fan on if you have a
bad ground connection on the thermosensor.

(---- checking the fan leg)
If all that checks out ok, check to make sure that one side of the
motor is tied to ground. If it is not, the schematic shows a junction
connector that must have slipped off.

If that checks out, it must be the fan motor but that is most unlikely
-- they don't go very much, I don't think. To absolutely make sure, hit
it with a hammer (figuratively, that is) by applying power to it and
see if it turns.

Obviously, you can try the above in any order. I'd try to do it myself
if I were you. Don't think it will be awfully hard to find and a dealer
will just hose you for hours of labor.

Hope this helps.
Remco

 

Hi Remco
I have checked the relay and have 12V at contact side (switch off)
and have 12V at coil side ( switch on, only), shorted contact side
and fan runs like a champ. I do not have 12V at the thermoswitch
plugin but do have ground on other wire. I run multimeter check on
wire from thermoswitch plugin to relay and got continuity at the
coil side of the relay, this leaves me a bit perplexed, could I have
continuity through a connection but not have enough volts to run the
motor? I am still looking for the connection between the relay and
thermoswitch.
Thanks
Ernie

 

Hi Ernie

Good, that makes sense one fuse being on all the time, the other is on
with the ignition switch on. The following tests will assume you have
the ignition on so you'll need 12V on both those contacts on the relay.

Ok, you should have 12V on one side of the thermo switch with the
relay plugged in. I should have made that a little clearer. Basically,
on one side of the coil you have 12V and, because the switch is open,
you should see that 12V on one side of the thermo switch as well. It
is weird that you have continuity on from the thermo switch to the coil
- I wonder if your socket has a bad connection. They are pinch type
connections, so maybe they are somehow bent out too much where the
relay just doesn't make contact. Since your multimeter probably has
nice fat contacts, you see continuity. Inspect the socket, definitely
-- you can bend those contacts back carefully, if that is what's
needed.

If that looks ok, put a thin wire in relay socket pins and carefully
plug the relay back in. That wire will just be pinched in by the relay.
The contact we're intested in is the coil side of the relay that
doesn't directly go to 12V -- this way you can see what the relay
sees. We're going to test the circuit live this time.
Get a temporary wire (clip lead or something like that) and hook it
between ground and this wire -- if you see the fan turn on, your relay
(including socket) is good. If not, check all contacts on the socket.

if it passes that test, unhook your temp ground connection and measure
the voltage across that point and ground. You should see 12V with the
thermo switch open. Shorting the thermo switch should make it go to
near 0 volt. If you don't seen a change, the wire from the switch to
the relay must be bad or the ground is bad. That cliplead test we just
did basically emulates what the thermo switch does and we know the
relay works -- it has to be wiring to the thermo switch.
If you see it change but not to zero volts, it means you have some
resistance in the path somewhere. I'd check the ground connection to
there thermo switch. Get your clip lead and clip it to the non-ground
connection of the thermo switch and ground. If the fan now turns on,
your ground connection to the switch is bad. If it doesn't turn on, the
wire from the switch to the relay must have some resistance -- perhaps
try clipping a lead directly from the switch to the relay and see what
happens. It is hard to believe that the wire changed its resistance,
but there is a junction connection according to the schematic. One side
of that junction does go to the ECM so let's hope we don't have to look
in that direction.

Btw, what happens when you turn on the AC? Do both fans turn on?

These problems are a pain to find but think how great you'll feel when
you keep that money in your pocket
You'll get it.

If you need quicker response, you can email me if you'd like.
Remco

 

Remco wrote:

I think you got the fuses reversed. The coil is fused by fuse # 13 in
the under-dash fuse box, the live relay contact is fuse by fuse #33 in
the under-hood fuse box.

 

I think you got the fuses reversed. The coil is fused by fuse # 13 in

Thanks for the clarification.
Unfortunately, Ernie is seeing power on both legs so where the fuses are is
moot: It would have been nice for him to find just a fuse blown.

 

Hi Remco
You are right again. I tried the thin wire in the relay sccket bit and
the fan came
on and runs fine. I didn't even need to run jumper to to switch the
wire alone took
up enough space to make contact. I took the wire out and bent the relay
pin just
slightly toward the socket (all four) and replaced the relay and fan
still worked fine.
This has been my first try at a web group and I must say it has been an
altogether
pleasant experience. Sort of like talking to a friend over the back
fence.
I could't send this as and email I didn't have your complete address, I
think I could have
infered it (add 131 to my email to reach me). I wanted to end this
post with a
solution anyway.
My regards to all, I appreciate the help
Ernie

 

thats what were all here for. its best to post back to the group anyway,
rather than private email. that way we ALL know how things turned out

 

Mike has a good point because someone else might have a similar problem
and your experience might help him/her too.

Glad it worked out, Ernie. Feels good to stick that money back in your
pocket, doesn't it?

Yeah, google mangles email addresses probably for antispam purposes. If
you use another newsgroup browser (even outlook express), you'll see
everyone's email addresses just fine.

Regards,
Remco

 

I've saved some of these messages for inclusion in the FAQ, if nobody
minds.

The only problem is that the thread's necessarily a bit scattershot, and
I'll need to rewrite the data to have a proper flow. If somebody wants to
do the rewrite, I'm more than happy to put that up that instead.

 

You go right ahead, Tegger - doing a good job on that faq.
Thanks!
Remco

 

Remco, I didn't answer your Btw question. No the fan did not come on
when the ac was turned on.
and Tegger feel free to edit and/or rewrite.
Thanks
Ernie