Electric Fan/Relay......Need some help!!!!

[rhodog77]

Hey guys,

I have installed a electric fan from skip white performance with a 50 amp relay. I have everything wired up but I can get the fan to kick on. The temp sender is set to open up at 200 and close at 185. I ran the motor up to 220 and still nothing. I thought that I had a bad sender so I spoke with skip white and they sent me another one. I installed it tonight and still nothing. My wiring kit is set up for both a relay and for a switch. I really want to stick with the relay but will run it with the switch if I have to. When I wire it to a switch, the fan works fine. The temp sensor is "ground seeking" unit. When the temp sensor reaches the preset temp the switch opens up and completes the ground which completes the relay to kick the fan on. Here is the issue, I know that the fan is wired correctly because when I disconnect the temp sensor wire and ground it to the motor or even to the pipe plug that the temp sensor is in...the fan kicks on like it is supposed to.

All I can guess is that the sender is bad or the sender is not registering the temp. I have it installed in the intake next to the water jacket. I dont know if installing it into the block somewhere will make a difference. Im pretty stumped at this point. If anyone has some tips or advice, I would really appreciate it. This is like the last thing keeping me from getting it on the road.

[ls1nova71]

If grounding the sender wire turns the fan on then it has to be the the sender. Are you sure the engine was actually above 180*, how did yoy verify it?

[Dan in Pasadena]

How about installing a ground strap from the engine to twhe frame, if you don't already have one?

[ls1nova71]

Originally Posted by Dan in Pasadena

How about installing a ground strap from the engine to twhe frame, if you don't already have one?

He said he can ground it to the pipe plug the sender is in and it comes on, so I would think its grounded.

[dwcsr]

What happens when you ground it to the body of the sensor? If it turns on then its the sensor. If not then you have to much pipe tape or sealer on the threads. You said it worked when you touched the pipe plug its threaded into so your motor grounds are fine. It is also possible that there is no water touching the sensor and it will not work without water touching the end.

Some times the spade terminal at the top gets twisted on installation and kills the sensor. This is the main reason for DOA sensors.

[rhodog77]

Then fan does kick on when I ground it to the body of sensor . This is the second sensor that I have tried. I thought the same thing about the fluid level not being high enough to register the sensor. I'm thinking about placing it in the block somewhere ,instead of the intake . I will probably swap out spade terminals is well
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[rhodog77]

Also my temp gauge seems to be in working order. I put a heat gun to the radiator hose and it was pretty close
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[RootBeer 6117]

Originally Posted by rhodog77

Then fan does kick on when I ground it to the body of sensor . This is the second sensor that I have tried. I thought the same thing about the fluid level not being high enough to register the sensor. I'm thinking about placing it in the block somewhere ,instead of the intake . I will probably swap out spade terminals is well
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rhodog, most of the GM temp sensors I have replaced have been in the cly head between the #1&3 cly there is a plug there for them.

[mr48chev]

Originally Posted by rhodog77

Then fan does kick on when I ground it to the body of sensor .
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If it doesn't ground out on the body of the sensor and grounds out on the pipe plug DW nailed as he usually does. Too much sealer on the sensor. The sensor has to ground to the engine to work.

[Russell Ashley]

If you have an ohm meter you could test the sender by putting it in a pan of water on the stove and bringing the heat up and see if it closes. I've tested a lot of thermostats and temp sensors this way. If you do test it this way remove it from the heat and let it cool naturally, don't dump cold water on it immediately.

Before I did that though, since you have two of them now, I'd just put one in the head where most Chevy's have the sensor and see if that doesn't fix the the problem.

[rhodog77]

Hey guys,

I currently have my temp gauge sending unit placed into the block between #1 and #3 cylinders. I think that there is one on the other side bewteen numbers 2 and 4.

Where do most people put the temp gauge sender. I have seen a bunch in the intake. Im hoping if I put the relay sender into the block that it will function properly.

thanks for the info. I think that I have a pretty good understanding how these sending unit and relays work. I just cant figure out whats wrong.

thanks again

[dwcsr]

Originally Posted by rhodog77

Hey guys,

I currently have my temp gauge sending unit placed into the block between #1 and #3 cylinders. I think that there is one on the other side bewteen numbers 2 and 4.

Where do most people put the temp gauge sender. I have seen a bunch in the intake. Im hoping if I put the relay sender into the block that it will function properly.

thanks for the info. I think that I have a pretty good understanding how these sending unit and relays work. I just cant figure out whats wrong.

thanks again

my temp sender is in one head and the fan switch in the other.

[OrrieG]

In my 64 chevelle the head location reads about 12-15 degrees hotter than the manifold did using the same gauge (VDO mechanical).

[rhodog77]

Orrie,

thats good info. I didnt want to ask a stupid question about water temp differing between the heads and the intake. I thought it would be the same.

dwcsr,

thats the route im going next. gauge sender in one head and relay sensor in the other. see if that works

[tmoble]

yes, there's no plugs in the early heads, there should be a couple on the thermostat crossove passage on the front of the manifold. my 65 327 heads don't have these holes either.

you know, right, that the switch *closes* at the desired temp to provide a ground to the relay? if you ground the wire from the relay to the metal body of the sender it should turn on the fans. If it doesn't something is wrong with the relay or the wiring at the relay. Maybe the trigger/ground wire is on the wrong terminal?

[Wheelie]

If you can ground the temp sender wire and it works your wiring is correct. Either you have an air pocket or your dash temp gauge is inaccurate and 99% of aftermarket senders for guages are off usually on the high side showing higher than actual temp.(which can be repaired with resistors from radio shack, if you want to know how to figure out which resistor let me know) When I install these fan relay kits I use an infrared thermometer on the t-stat housing to verify and not go by the dash gauge. Also when i fill up the cars with coolant I use a coolant funnel (google it, they are usually yellow) that allows the system to "burp" while it is running.

[JPH]

I just install this set up on my truck and have had no problems so far.
Do you have the brown wire on the relay connected to the IGN and if so are you sure it’s getting power?