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Bad relay = cooling fan won’t come on

A

Andy69

Veteran Member
Senior Member
Figured that out. The rely clicks but the fan doesn’t work.

The relay is a 30A part no 0-1432785-1

It’s been a couple years but I’m pretty sure I bought the American Autowire universal fan relay kit. This is the relay it came with but looking the kit up I see it comes with a 40A.

Replace with a 40 or another 30? I’m trying to figure out what Spahl recommends for their 16” single fans.

Edit: all the Spahl relay kits come with a 40. That’s probably what it need but I don’t want to smoke the wiring harness
 
The relay clicking means the relay is working so now its time to check where you're losing the voltage. Use a volt meter or a test light and make sure you're getting 12 V to the fan. If you are then check that you have a good ground at the fan too. If you have both 12 V and ground then its a bad fan motor.
If there's no voltage to the fan then the relay is faulty.
I've seen these really cheap 12v test lights that have a volt meter in the handle in case you don't have one.
 
Yes Id check the fan with contacts against a battery bypassing all other electronics. If your fan is hardwired (with no disconnects for this) and you don't want to cut anything, you can do this with jumper wires in place of the relay. One to the power terminal from the battery, and one to ground.

Also you can check the relay with a multi meter for resistance and a 12V battery. But I suspect the relay is good as already stated. though I have seen relays that "click" with corrosion on relay contacts.

SPALs are outstanding fans and the only ones Ill buy.
 
Ok I figured it out. It was dumb. I had forgotten there was an inline 30A fuse and it had blown :clonk:
 
Not yet. That's the next thing. I'll test it again and it it blows a second time then I'll have to start digging.

The fan worked perfectly the first time - came on at the proper temp and went off at the proper temp but then never came back on again
 
Harbor freight now carries the PowerProbe lineup. This is a tester that can power up a fan circuit or your stop lights or anything that isn't working and you need to diagnose whats wrong.


I bought mine 20 yrs ago and it works great. It comes with a 20 ft cord. With it you can provide power or ground to anything that isn't working. No need for a separate 12V battery or extra jumper wires.
The Harbor freight one is $169 but there are others on the net that are priced a lot less it just depends on what you're looking for pricewise.
 
I tested it again and the fan didn't come on at the appropriate temp. Replaced the fuse, fan came on immediately but then didn't go off at the appropriate time.

I think it's blowing when I start the car. The relay clicks every time I disconnect the wire from the temp sensor in the intake. If the fuse is good, the fan runs when it's connected, stops when disconnected. I'm going to try a new temp sensor. I used a 185 on 175 off, maybe I should try a slightly higher temp?
 
Now it doesn't work at all. Notjhing from the relay.

this is why this fucking car is taking so long. Really sick of dealing with this shit.
 
A quick test of the sending unit is easy. Take the wire(s) off of it. Then take your 12V test light and hook it up to the Positive cable on the battery, this is backwards of the normal way of connecting a 12V test light. With the test light hooked up to the positive + cable, anytime you touch something that's grounded with the test lights probe the light should light up.

So most sending units for electric cooling fans will be open when the engine is cool but as the engine reaches the temp when the fans should come on the sending unit or sensor will become grounded.
So now start the car run it till its hot and touch the end of the sensor (or sending unit) and the test light should light up.

If its a 2 wire sending unit there is a different way to check the sender.
 
Andy, I just checked and I have a brand new Flex-a-light controller that is sitting on my parts shelf. Look at the pick below and see if you want it. Its yours for the low price of FREE.

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1734730138531.png
 
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It sounds like you're using a sensor activated fan switch. The one I have is just a probe that sticks in the radiator fins next to the water inlet of the radiator. Then the round dial is turned and sets the desired "On" Temp of you desire between 160* to 240*.

The downside (in my opinion) to this box is:
1) Its a probe style (I prefer sensor style).
2) It "could" be only an "On" switch. for example If its set to come on at its lowest temp of 160* the fan will remain on the entire time as is more likely that the temp will never get down to 160* while its running. More than likely the engine will stay at about 185* to 195*. So if you set it to 185* it has a better chance of coming back to 185* and shutting off for a brief time before coming back on again.

MY fans are mounted on a rocker switch and NOT a thermal switch like your sensor or the box I posted. MY thoughts (and the engine builder) is you should never wait till the engine gets heat soaked to start cooling. Once an engine reaches a certain temp, lets say 185*, the cooling system fans must come on, cool quick enough to stop the temp from climbing and then maintain a temp. That's hard on a cooling system.

So I run a high flow 160* thermostat. I start the Chevelle and let it warm up and drive. Once the engine hits about 100*, I turn on my fans from the rocker switch. They stay on till I turn them off. That way the engine maintains a gradual warming until it hits its natural peak and stays there. Lately its been about 45-55* out and I don't turn the fans on as I'm not sitting long enough for the temp to go high.

I NEVER see temps above 185* in the Florida summer idling in traffic with the A/C on. Which is a lot to ask a 600hp car driven like a race car. Especially a 406ci that were notorious for high temps..

I have other items that help keep temps down as well.

Anyone's Thoughts? Great info from the other guys as well.
 
I have a dual Efan setup and 1 fan runs from a relay powered from IGN spade on the fuse box so as long as engine is running it’s on, 2nd fan is on another relay and an adjustable Hayden or Flexalite? Tstat similar to what Mike is showing but not a probe but a sensor in the intake near the Tstat housing, my engine runs 160-180ish
 
I like your setup with two fans and think that's probably the best of both worlds.

Like I said, My big fan is only on a switch. My secondary is a pusher on the front of the A/C condenser that comes on when the A/C is on. Its on a trinary switch for the A/C
 
OK, so had a chance to do some more diagnosis. There is a fuse in the block for the fan, that's good. Relay tested good. I checked the ground wire from the temp sensor to the relay and intially it was open and then after messing with it a bit I had continuity, so I think that's going to be why the relay wasn't working. I still have the blowing underhood fan fuse issue. It takes power directly from the battery and I have it kind of mickey moused so I]m looking for a battery cable/terminal with multiple outputs. I think that should fix the issue.
 
Andy69 said:
OK, so had a chance to do some more diagnosis. There is a fuse in the block for the fan, that's good. Relay tested good. I checked the ground wire from the temp sensor to the relay and intially it was open and then after messing with it a bit I had continuity, so I think that's going to be why the relay wasn't working. I still have the blowing underhood fan fuse issue. It takes power directly from the battery and I have it kind of mickey moused so I]m looking for a battery cable/terminal with multiple outputs. I think that should fix the issue.
Click to expand...
Can you put it on a circuit breaker?
 
Shovelrick said:
Can you put it on a circuit breaker?
Click to expand...

I'll try that if cleaning up the battery terminal connection doesn't work. I have a cable with a standard top post terminal with one extra wire for accessories and I've got two leads hooked up to that. Not sure why I did it that way but I've ordered a cable with 3/8' on both ends along with a terminal with three outputs. The battery cable is also long enough to fish through the frame which I should have done before.
 
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