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I've been trying that for the last twenty years, i don't think "santa" is much of a mechanic.

 

Anyway, i have an update. I have found several switches that will work in the T-stat housing (3/8 x 18) one of which i tried. It is a simple switched ground that makes contact at a certain temp, in this case about 224* (yes i know thats a little hot)  It worked flawlessly and also added to my confidence that my gauge is working spot on.  So, I put the switch in wired it to the fan plug and used another wire as a direct line to battery (+). Temp gauge was smack dab on 230* when the fan kicked on, swiftly bring the temp back down to 212* and turning itself off, all the while my other electric fan did nothing, the one using the stock sensor.

 

87manche might have already posted this link, but i will put it up again just in case. Summit racing sells the exact switch i would like to have but they want $40 for it!

 

http://www.summitracing.com/parts/bci-75099

 

I got mine from NAPA the connector and switch together were about $32

 

For a super simple dual electric fan setup that is entirely autonomous, i think the above summit switch and the stock renix switch paired with two OEM fans would make an excellent system.

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Update:

 

Brand   new  sensor  in place, back probing the socket the entire time, constant 12v, plugs are makeing good conntact.  Still. Nothing.  :headpop:      And this time I let that B*TCH peg!   I'm talkin 260* and still not a freakin thing.  I am completely baffled now.   :wall:

 

I honestly am completely out of ideas now, there is zero reason for this fan not to come on. The only thing i can think of now is to buy a sensor that is of a much lower temp setting, thankfully i have located several. :)  But thats more money, that i don't have. :(

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Update:

 

Brand   new  sensor  in place, back probing the socket the entire time, constant 12v, plugs are makeing good conntact.  Still. Nothing.  :headpop:      And this time I let that B*TCH peg!   I'm talkin 260* and still not a freakin thing.  I am completely baffled now.   :wall:

 

I honestly am completely out of ideas now, there is zero reason for this fan not to come on. The only thing i can think of now is to buy a sensor that is of a much lower temp setting, thankfully i have located several. :)  But thats more money, that i don't have. :(

Need a infrared thermometer like I (and Crusier) said. Sorry about the spent $$$ tho - it can be frustrating.

 

Just for gits and shiggles: You say the fan comes on when the A/C is on, and it works when you run a jumper wire directly to the switch (and you hear the relay 'click'). The only other input in the equation is the ECM. Could the ECM not be responding when the temp indicates the switch should come on?

 

You could temporarily swap out the ECM (if you have an extra - if not I have one I'd loan ya), or - if you own (or could borrow) a Snapon MT2500 (the red brick) it could tell you what "reading" the ECM is getting from the system.

 

Good Luck!

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The ECU doesn't control the fan on a Renix. It's a simple switch system.

Ah. Didn't know that.

 

So the ECM only uses the temp sender (down low on the block near knock sensor) for going from closed to open mode? I though it also used that temp for the fan switch circuit as well....

 

So if only the switch controls the circuit, it should always have 12V power and when tripped it allows it to go to the fan. What is the in-line relay for?

 

Learn something new every day...

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There are 2 relays for that circuit. One that is sensed from A/C circuit and one that is sensed from the coolant switch. There is a diode in circuit from coolant switch relay that blocks current to A/C relay to prevent back feed into relay that is located under C101 connector. It will fail circuit protection if diode is bad. You can still have A/C request to fan and not have coolant switch request to fan. I would agree to check relay befor anything else if you have verified that coolant switch and fan are both in working condition. Problem sounds local to coolant switch circuit.

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I memory serves me right coolant switch is ground side switching and not B+ switching

 

The HOs use ground switching and the Renix B+ switching to energize the E-fan.

 

OP, this thread should help you check out the fan coolant circuit. Look at the schematic.

 

http://comancheclub.com/topic/36031-cooling-fan-relay/?hl=switched&do=findComment&comment=360557

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Need a infrared thermometer like I (and Crusier) said. Sorry about the spent $$$ tho - it can be frustrating.

 

 

Ya, i will be checking into that and seeing about getting a new sending unit, possibly gauge too.  Thankfully i was able to return that switch without any problems, it helps to be on a first name basis at the parts store. :thumbsup:

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Fixed.  Turns out its quite important to fill the radiator with coolant and not just the overflow bottle.   :dunce:     Just because I could see circulation in the coolant bottle, did the proper bleeding via the gauge sending unit at the back of the head, AND had coolant pour out the switch bung did NOT mean there was sufficient liquid actually IN the radiator.   On a whim i decided to fill the system through the top radiator hose. When i took it for a drive i got out and popped the hood to check for any leaks/problems and low and behold my fan decided to kick on. I let it cycle several more times just to be certain it wasnt a fluke. Yup it seems like all is well, this is with my old switch too.  Now i am REALLY looking forward to getting in my other switch. This will make a pretty effective system when its all setup.

 

Ftpiercecracker,

 

now on to sovle world hunger.  :D

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