yea after I just made a thread about the fan switches, post installation is now a problem. making this so it gets the right attention.
I just put a new 180 thermostat in along with this hypertech 4028 fan switch. the fan seems to kick on at about 150, and stays on when you turn the ignition on (or start) after several minutes of the car being shutdown. but let's say it's off all day after that, it wont come on if i turn it to on.
I just disconnected the coolant temperature sensor on the sensor by cyl #1 when the fan was running and it stayed running. the coolant sensor on the intake is new too.
can this actually be a relay?

 

 

reeeeeeally want to look away from draining the coolant and removing and reinstalling one of those damn things again.
i don't have an ohm meter, but can I just unplug the harness to it and check it that way? what should it read? does the car have to be running or anything?
also, i don't see how this thing can open and close. maybe on the old sensor, but not this.

 

 

That's the sending unit for your gauge.
CTS is next to the thermostat housing and has nothing to do with the fan.
The fan switch is the ONLY (temperature dictated) fan control for a TBI.

It's either on, or off at it's preset temperature. There is no in between.

 

sensors make sense.
but it doesn't matter whether the car is running to test the switch?
I have a feeling it's a relay, but here's what the guy at hypertech told me. the fan switch gets a different reading than the one i'm seeing. i asked him about the 40 degree difference and he said yea. but if the thermostat is open, it shouldn't be a 40 degree difference, right?

 

If your saying the car stays at around 150 with a 180 thermostat then that sounds as if your thermostat is staying open. With a fan that's running at those low temperatures I can see that happening.(running cold that is) I run a manually switched axillary fan from start up and a 180 thermostat and my car stays around 190.

 

I JUST put it in. that was the issue with the old thermostat. if it was stuck open, the fan wouldn't come on.

 

It's not so much the car has to run as temperature. The fan switch is a thermostatic switch, it is not sensor in the term it is not supplying 'information' to anything. It's on or off.

The fan switch controls the coil side ground of the relay. Switched +12v is supplied from the fuse panel. Unless you have a ground fault, the relay can not switch on by itself, regardless of temp (well, unless it's on fire and melting together at the contacts), without signal from the fan switch.

You have a junk,overpriced fan switch, you're not the first. Of course the supplier isn't going to admit it....

 

The fan is coming on before the thermostat is even opening... or at least, that's how I read it.

 

so could it be the relay?

 

I know we had a slight clash in your initial post about the fan switch but, did you at least read my post ?
I'm really not trying to be a d--k about this and trying to give you advice.

The relay only works (coil side) by power input. The coil is charged (+12v input) with a switched source from the ignition though the fuse panel.

The fan switch controls the coil side ground, When the stock switch reached 238°F, it will close to ground, completing the circuit and making the relay switch (closing the contactor) thus,turning on the fan

The one you bought, just closes to ground at a lower temperature. You're problem is, the switch is bad and closing at a temperature to low.

The relay can not close without a ground on the coil side (fan switch) or a short to ground (bad wiring). If there is a short to ground, the fan runs always (key on).

HTH...

 

A thermostat and a thermal switch are two different things in two different places. Kragen , advanced auto ,Napa should offer a quality thermal switch(fan switch).What Ive found is three different switches. They come on at on at 180 or 195.( I think the stock switch is 225.) You get to choose the temperature with a switch of your choice. I'm only trying to help. Take what you can use and leave the rest.

 

sorry to disappoint you, but I didn't fully understand you.

 

Its too cold man, i replaced my t-stat because the engine didnt get hot enough. i put in a mr gasket 180*. Its High flow, but it sucks because still too cold, doesnt warm fully, cools down too fast. below 180 when driving in cold. im going to put in a 195* stock with holes drilled for bubbles. that should help. And If i read your post correctly, the fans wont turn on at start position until the car is warm. the fans stay on after shutdown with key in ignition is because theyre hot still. But i could have read your post wrong. to test the relay, turn the a/c on. could be a bad wire in the circuit. the fan switch connector between 6 and 8 cylinders gets loose sometimes. i had to replace mine with a western union joint solder and heat shrink. good luck

 

I know it's too cold man.
you did read it wrong. it goes on even though it's cold. and it probably will stay running forever when ignition is just to on! i had it running for like 10-15 minutes after about an hour after shutoff. it is no longer hot at that point. especially if i can touch the block without it burning me.
we put a new ground tip on the fan switch wire. i even heat wrapped the whole thing just in case. no luck.
ron , it's a 200 degree on fan switch. the fan running so early doesn't let it get near it. I'm going to call these guys again and hopefully a new switch will do it.