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Coolant Temp Sensor help prease!

Z71paramedic

Z71paramedic

Wait....What???
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Ok, long story short I have a brand new aluminum rad from Entropy with the dual fan setup and their wiring harness. I run the truck (yeah, that's right, it runs!) and it gets up to temp, t-stat opens but the fans never come on. I've jumpered the wires coming from the temp sender and the fans kick on. I put my multimeter on the wires coming off the sender and get no ohm reading. I assume it's just a bad unit which is my luck. Problem is I don't want to wait for them to ship me another one, I want to drive the thing. So, can anyone ID this temp sender so I can get one from the parts store, or is it a custom deal?

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gm used a few diffrent temps for there fuel injected cameros / transams/ firebirds back in the mid 80's that most aftermarket still use today.

its not like your switch ( and 10+ years as mechanic i have never seen one like yours ) but can work with sensor and pigtail. but have to use a relay to run the fans cause of amp draw.
 
I've got two relays, and a fuse per fan. I'm just not getting any juice (or ground I guess) from the temp switch. I was thinking a standard gm temp switch with metri-pack connector would work, I just have to lengthen the wires a bit:doah:
 
Yeah, I let it get up to @220 today and said F it after that. According to entropy's site it's a 180* sensor, same as my t-stat. I plan to give them a call in the morning too, just don't want to wait for them to ship me a new one...
 
Z71paramedic said:
Yeah, I let it get up to @220 today and said F it after that. According to entropy's site it's a 180* sensor, same as my t-stat. I plan to give them a call in the morning too, just don't want to wait for them to ship me a new one...
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It's also possible that the spot you're reading the temp from is a higher temp than where the sensor is. Those don't really go bad.

I don't think you will get any ohm reading through it when it's below temp. You should only get continuity when it's above temp that's how it's works I think.

Also, the sensor should have two ratings, an "on" temp and an "off" temp. Make sure the "off" temp is above the thermostat temp.

If your thermostat temp is 180, then you want a sensor that turns both off and on somewhere higher than 180, that way your thermostat will make sure the temp stays at least 180 and then the fans will regulate the temp to be between 180 and whatever the "on" temp of the sensor is. If both are set to the same temp, your fans will never shut off since the thermostat will always keep it above 180.

For example, I have a 195 thermostat and a sensor that turns the fans on@210 and off@200. It works great in that many times when there is enough airflow through the radiator (like on the freeway) it stays near the thermostat temp even without the fans turning on. Once I stop or am moving really slow with no natural airflow, then the fans turn on as needed.






-Brian
 
Temp sender for the gauge is in the standard spot on the left head. I figured it could be a temperature difference too, that's why I let it get all the way up to 220. I'll call the dude in the AM and see what he has to say. :popcorn:
 
So if you want to drive it just ground the relay so the fan is on when the key is on (assuming the relay power comes from the ignition switch and you are switching a battery supply). Then order another switch. By the way, that potted pigtail switch looks like it's from 1975. Summit or painless sell one that is one piece, the summit one is just one wire to ground the relay.
 
What happens when you unwire the temp switch? If the fans turn on then the temp switch is your issue. If not you have other problems and the temp switch might be ok. Has it worked in the past or is this a new install.
When I did mine I temporary wired my fans (used) to test them then as I added each piece I double checked myself after every part was added to the system

Do what did manufacturer say?
 
The teflon doesn't matter with the two wire switch, the housing doesn't flow any current. I haven't found the teflon to matter with the one wire switch either, I always get plenty of ground to switch the relay. Now, on the one wire sending units, that could be an issue, because it can make your temp reading faulty because the gauge is reading resistance through the threads as well.
 
Ok, thanks for the help guys. I talked to the guy just now and it turns out I wired the relay wrong:doah: Though in my defense it came with no wiring diagram or instructions. I wired the relays to match the colors on the pigtail. Turns out I should have wired one wire to be ign hot and the other to BOTH relays. I'll go switch that around and report back:thumb:
 
i did that 1 time with a old relay temp unit on a car. didnt have paper work for it.

took for test drive no fan ? ? ? :dunno:

got back and looked and realized what i did and swaped it and bam good to go. :haha:

good thing the radiator was a aluminum BeCool unit or the car would have over heated.
 
Forgot to update, but that did the trick. I added 12v to the one wire, and split the other to the two relays and the fans kicked on right when they should.:woot: I'm almost done with this pig now!!
 
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