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Username Post: electric fan sender unit        (Topic#347852)
Mmo 
Gold Supporting Member
Posts: 11
Mmo
Age: 53
Loc: Toronto, west side
Reg: 09-24-17
10-24-17 06:57 AM - Post#2711939    

Hey Gents

likely familiar with this one, but mine's little different. 72 Blazer, but with a 454 crate engine. electric fan mod, doesn't work. i took the wire from the temp sensor in intake manifold and grounded to manifold and outside of sensor, both times fan comes on. got a new aftermarket temp sensor, still no joy.
don't think it has a relay, but i swapped the 2 in fuse box. even switched the wires between temp sensor for gauge and this, incase they were installed wrong. only had this blazer couple months, and fan has never worked for me.
looking at Fan and shroud, says Ford on it?! took it's part number to Ford dealer, and is from a 2003-11 crown victoria. their sensor has 2 prongs and wires, and is i think AC. didn't think it would work, and it didn't.
rather not RR fan and shroud with a matched sending unit. aluminum rad likely different size than original.
LMC has one, but is completely different looking.

i'm stuck fellas. has to be just a simple DC grounding unit to make the circuit. fan comes on when grounding its one wire.
i put the old temp sensor in boiling water, touched the wire connect and outside with continuity tester, of course not connecting. couldn't get continuity with Ford temp sensor either, but i think it's more complicated.

rude comments and suggestions welcome.



Thanks Fellas
mighty copper Blazer


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25311
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
10-24-17 08:06 AM - Post#2711949    
    In response to Mmo

Ya doing it wrong, Yank!!

Welcome to the site. The best place to use a temp sensor is in the head. My dual fan set up uses the right side head. The left side is for a digital temp gauge.

Can you post a fan pic? Is it a Mark VIII type fan? Is the fan relay activated?

Read this: http://www.off-road.com/trucks-4x4/project/pr oject...

This one too, both cover Furd fans.
»http://www.fordmuscle.com/archives/2003/02/elec tri...«

Most temp sensors have to reach a certain temp before they ground out. Mine has a 205 degree on and 190 degree off operation. Both fans have a 30 amp fuse and individual relay power/activation.



'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
Mmo 
Gold Supporting Member
Posts: 11
Mmo
Age: 53
Loc: Toronto, west side
Reg: 09-24-17
10-24-17 11:11 AM - Post#2711974    
    In response to gchemist

thanks for your prompt response

only 2 pictures handy show couple different part numbers, but too big to attach.

the intake manifold (edelbrock) is the only place for screwing in temp gauge sensor and this fan temp sensor. close to top rad hose elbow. has aluminum bow tie heads.

i saw from your link that ford lincoln electric fans are popular. this one is from a crown vic, but maybe the same parts.

if there is a relay, it’s likely a small black box wired next to fuse box, inside firewall. the 2 round circular units inserted in fuse box, i think they’re relays, and those were the 2 i swapped. even with both out the electric fan will come on when i ground the wire to the temp sensor.

although this truck is professionally rewired, the new fuse box has one fuse labelled fan, but i think its for the interior heat fan, which is missing as the vehicle has no heater core or associated plumbing. another thing I’ve gotta do, with all parts currently cluttering my garage. and, elec cooling fan comes on again when grounded, without this fuse in.

I’m 95% certain original temp sensors faulty, couldn’t make continuity in boiling water using my continuity tester.
my torturous questions:
if this crown vic ford elec fan is AC, as that car is apparently wired, will it work in my 72 Blazer DC system? it does come on when grounded, so it should.
and, if the fan comes on when grounded, does this mean the relay, if it has one, has to be working fine?

too much work fitting new fan(s) and shroud to this new aluminum rad. like to fix this.

keep em coming…….



Thanks Fellas
mighty copper Blazer


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25311
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
10-25-17 05:26 AM - Post#2712083    
    In response to Mmo

If the grounded wire is not directly fan ground, yes, it's going through a relay. The relay is working. Pull the relay and ground. The fan should not come on. You may need to install an adapter at the intake port. With an adapter, you can have two sensors. One for gauge and one for fan control. With the switch being on the intake, you don't have an "activation" ground.

The ZZ4 in my truck has aluminum heads. They like to run at 195. At lower temp performance is bad. It eats gas bad. Above 210 degrees, the intake and edelbrock carb don't like the extra heat.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
Mmo 
Gold Supporting Member
Posts: 11
Mmo
Age: 53
Loc: Toronto, west side
Reg: 09-24-17
10-25-17 07:37 AM - Post#2712099    
    In response to gchemist

thanks G. there are 2 separate sensors on intake manifold, with the temp gauge sensor working.
just the one wire connected to the temp sensor for electric fan.

don't understand what you mean by not having an "activation ground."
operationally the same,as intake and heads are bonded.

you reckon this former ford crown vic electric fan needs a dual sensor, and will come on when temp gauge rises?

i just don't understand why a simple DC temp sensor, which grounds and makes the circuit when hot, wouldn't work.
could it work?
rather not put on a manual switch.

frustrating.

keep em coming



Thanks Fellas
mighty copper Blazer


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25311
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
10-25-17 08:27 AM - Post#2712107    
    In response to Mmo

Can you send me your intake pics? It help me understand better. Below is my setup.

I thought you were using the temp gauge sensor as your fan activation ground. Your sensor may be bad.

Attachment: fans.jpg (169.8 KB) 26 View(s)


Dual LS1 fan setup.


'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
raycow 
DECEASED
Posts: 27999
raycow
Loc: San Francisco, CA
Reg: 11-26-02
10-26-17 07:39 PM - Post#2712298    
    In response to Mmo

Everyone seems to be tiptoeing around the elephant in the room and nobody has asked the obvious question yet:
What is the specified "close" temp on the sensor you are using? To put it another way, how do you know it isn't higher than 212°?

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
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