Bad fan switch or relay?
 

I have my fan switch grounded with a toggle switch: green wire/with white stripe, so I can turn on the fan when I want to. I had the toggle switch off, and the fan wouldn't automatically come on like it should. Would this be a bad fan switch, or a bad relay? 92 RS 5.0 TBI

Re: Bad fan switch or relay?
 

might be a bad fan motor. time to beak out the ol test light to see where you are and arent getting power. the orange wire is usually power, atlest it is on my 89.

Re: Bad fan switch or relay?
 

The fan motor comes on with the toggle switch, but not when the ground switch is off.

Re: Bad fan switch or relay?
 

Get rid of the toggle switch. When it's off the circuit is broken so the fan switch wont work as it's supposed to.

Re: Bad fan switch or relay?
 

Get rid of the toggle switch OOh My! Anyway, grounding the fan switch is a popular method of manually overriding the fan so the engine temp doesn't reach 225. If the switch is off (not grounded), the fan will come on with the fan switch when it's working anyway. If I didn't have the ground switch hooked up, I would have overheated.

I did find out that the fan switch is not working right. If it was a relay, the fan wouldn't have come on at all.

Re: Bad fan switch or relay?
 

IIRC, the switch on TBI engines does not close at 225 but at much higher temperatures. The number 238 rings a bell (but I might be off a few degrees). Yes, it is pretty high and it looks almost like the engine will boil out but it's just an overheat switch and as long as it works, the engine will never see 240.
So to test out the switch, just let the engine idle until you see 245 (yes, it's hot but not dangerous). If the fan doesn't kick in before reaching 245, it's time for a new switch.
Btw, make sure you are reading the actual engine temperature. The dash gauge and sensor are not very accurate to begin with so I recommend to use an external thermometer (non-contact IR type or similar) to see what the actual engine temperature is.

Hope this helps.
Lou

Re: Bad fan switch or relay?
 

I know the gauges are not accurate, but my gauge read higher than before, and the fan didn't kick on. I didn't wanna push the envelope, so I cooled it down with the override switch. I am gonna replace the switch soon. About 11.00 at autozone.

Re: Bad fan switch or relay?
 

If I understand correctly, you want the fan to be able to turn on automatically when the engine hits a certain temp (via the ground switch).

And you want to be able to manually control the fan on/off with a toggle.

SO basically you want to control the fan switch with a toggle and still have the temperature ground switch turn the fan on if you start getting too hot?????

Easy to fix. If I understand how you have it wired. It sounds like you have both switches in series.

Now install your toggle switch with a grounded wire in parallel to the temperature switch. That way when you hit the toggle, the relay gets ground and the fan turns on. Also if the toggle is off, the temperature rises, the temperature switch closes, the relay gets ground, the fan turns on.

Re: Bad fan switch or relay?
 

I believe you are describing the way I have it wired. When the weather is cool, and I am cruising 35-40 or faster, the fan need not be on to keep the coolant temp at 180*. When it is hot and in standstill or slow traffic, I want to be able to keep things cooler than 225* which is too hot for me. I believe too much heat will rob performance and engine life.

Re: Bad fan switch or relay?
 

Im lost.

Does it work how you want it too?

Can you draw how you have it wired?

Re: Bad fan switch or relay?
 

The original thread started with "do I have a bad fan switch or bad relay" . Since then I have figured out it's my fan switch that is bad.

I can manually override the fan switch by grounding the green w/white stripe wire that connects to the fan switch to the fan relay. I can turn on the electric fan with a toggle switch I have under the dash.

Re: Bad fan switch or relay?
 

Ah, I think I finally know what you are talking about. Or atleast Im glad you know.

So it is all working properly now?

Re: Bad fan switch or relay?
 

I'm replacing the fan switch today. Then everything will be alright.

Re: Bad fan switch or relay?
 

Get ready to drink some coolant if you're doing it from under the car. :)
Though, it's not as bad as replacing the knock sensor, that hole has more static pressure on it and is a bi*ch to thread back in.

I am curious what temperature the new switch will close at. The stock replacement should still be at 235+ F.

Lou

Re: Bad fan switch or relay?
 

Well Lou, I have drank worse stuff. Are you saying the temp sensor is difficult to thread in, or the knock sensor is difficult?

Re: Bad fan switch or relay?
 

The knock sensor is definitely worse than the temp switch, in my own experience.
Though the temp switch is not easy to get to (unless you have headers).

Btw, do not use any tape on the threads of the temp switch. It needs to have good contact with the head because that's how it grounds the relay.

If you have a bucket handy, you can always drain about a gallon of coolant to drop the coolant level below the heads. That way, you won't loose any coolant or get wet when swapping the switch.

Lou

P.S.: I envy your location right now. I bet you don't have 105. :)

Re: Bad fan switch or relay?
 

Would using plumber's pipe dope work, or would it interfere with contact with the heads?

Yeah, it's gonna be 82 and sunny for a high today. In 3 months I will be envying your location. I have to put my Camaros up for the winter.

Re: Bad fan switch or relay?
 

It is not recommended to use any pipe sealant to ensure good contact. The threads on the switch are brass to provide a good seal on its own (brass is soft metal). Just tighten it well and it won't leak.

We haven't had rain since January, trees are dying, bushes too, grass has been gone since May. 111°F isn't rare these days. The hottest and driest summer so far (I have never used 1.5 megawatts of electricity in one moth before).
I'd kill for 82. :) Sure, come over in 3 months, we should be down to 80's by then.

Lou

Re: Bad fan switch or relay?
 

Ok, I'm on the same page now. When I replaced the temp sensor, it was brass, and I didn't use anything on the threads.

As far as the weather goes, I think we are in a la nina pattern. Here we have been getting lots of rain this summer, and there are mushrooms and toad stools growing everywhere. The southwest gets dry. When trees die, that's severe! Al Gore is still wrong wrong wrong!

Re: Bad fan switch or relay?
 

Any sensor that has 2 or 3 wires on our GM engines can use thread sealant because the ECM provides separate ground (black wire). But for single-wire sensors/switches, the ground is provided from the block so that's why one should not use any thread sealant.

We have only 3 trees left from the 8 we had before. We are used to the heat but the drought is the killer. I wonder when the rednecks down here will try to pin it on Obama. :lol:

Re: Bad fan switch or relay?
 

OK since the the sensor has a green/white stripe only, then the contact with the block is crucial. Maybe that's why it flew south.

That's a lot of trees. They take a life time to grow. What kind of trees are they?

Re: Bad fan switch or relay?
 

I am trying to get the connector off the sensor, but it feels brittle. Does anyone know how to remove the wire off the fan switch?

Re: Bad fan switch or relay?
 

Just an update here... I removed the connector and it fell apart. I was able to tape it to the wire, but I don't trust the connection to last. I will need to find a connector somewhere. The fan does come on now when it reaches about 225*, so it works for now.

Re: Bad fan switch or relay?
 

Unplug the plug from the switch and put it to ground, with the key on your fan should be on, if not you have a bad fan motor or relay.

Re: Bad fan switch or relay?
 

Yes, that test was performed and the switch replaced. The car has been back on the road for almost a month now.
Thank you for chiming in.

Stevolwevol, to answer your question (sorry it's so late), somebody decided to plant Canadian Maples in the desert of Texas. Many smart people here as you can see. :)
We are out of the 115's and next week looks like 100 degrees. The fall is finally here. :-D
Driving around in my Z28 convertible is much more enjoyable now.

Re: Bad fan switch or relay?
 

I have a ground toggle switch I placed under the dash. I use it so it doesn't get too hot in traffic. It just can't be good for an engine to get 230* then back down to 195. Up, down, up down. Sounds like flawed engineering.

You said down to 100?? yikes! We had a good summer, but too darn wet. Not trying to rub it in. Lots of mosquitos, spiders, mowing twice a week...

Re: Bad fan switch or relay?
 

Flawed engineering? Do you even realize what car you own? :chevy:
Our engines can handle 230 degrees, no problem. The "standard" operating temperature is 220, per spec. That's why the Fan On temperature is set at 235+.

I know you guys got some wet weather. Then there are the floods on the East Coast. Europe has had an unusually wet and cold summer (50's and rain). But Texas is suffering the worst drought in centuries. With all the fires on top of that.
So talk about crazy weather! We are getting ready to move.

Re: Bad fan switch or relay?
 

Yeah I'd say it's flawed if that's a good word. The high temps are so the cars pass emissions testing. Not for engine longevity.

We are not in a flood prone area thankfully. Move where?

Re: Bad fan switch or relay?
 

You are right, they chose to run the engines at higher temperatures for better emissions.

We are looking into the Carolinas. Decent weather, good people, hopefully decent jobs.
And I can drive my convertible there with not much rain or snow.