Rewiring dual SPAL fans - experience & questions
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Pro
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From: Ontario
Rewiring dual SPAL fans - experience & questions
When I went to set up the SPAL PWM controller, on my dual SPAL fans, the controller crapped out on me! See:
http://forums.corvetteforum.com/show....php?t=1734351
So I decided to rip the whole thing out and rewire it with a pair of relays and temperature switches, simple and old school. That's when the fun began!
Upon trying to remove the "almost new" SPAL temperature sensor, from the passenger side head, it snapped in half!
I was having nightmares about pulling the head to drill out the sensor, then I remembered that I had to install a 1/2" x 3/8" bushing to accomodate the sensor. Luckily I was able to get a socket on the bushing and remove it.
My new relays and temperature switches arrived on Friday and I finally got it all wired up yesterday.
Now the fans work great, coming on and going off with no problems.
However, I have one question. When the fans are running I am seeing quite a large swing in the ammeter reading - +20 to +30 amps depending on how many fans are running. I know that these fans draw a lot of current, but should it be wired so that it doesn't draw thru the charging circuit? Or do I have a problem with my battery?
TIA
Dave
http://forums.corvetteforum.com/show....php?t=1734351
So I decided to rip the whole thing out and rewire it with a pair of relays and temperature switches, simple and old school. That's when the fun began!
Upon trying to remove the "almost new" SPAL temperature sensor, from the passenger side head, it snapped in half!
I was having nightmares about pulling the head to drill out the sensor, then I remembered that I had to install a 1/2" x 3/8" bushing to accomodate the sensor. Luckily I was able to get a socket on the bushing and remove it.
My new relays and temperature switches arrived on Friday and I finally got it all wired up yesterday.
Now the fans work great, coming on and going off with no problems.
However, I have one question. When the fans are running I am seeing quite a large swing in the ammeter reading - +20 to +30 amps depending on how many fans are running. I know that these fans draw a lot of current, but should it be wired so that it doesn't draw thru the charging circuit? Or do I have a problem with my battery?
TIA
Dave
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
No it will not. It will basically split the electrical system, normal path for the car, new path for the fans. Only issue is you will not have current monitoring for the fan circuit, but thats really a non issue. As long as the fan circuit is protected with a fuse of some sort.
Where did you tie in the hot for the fans?
Where did you tie in the hot for the fans?
Thread Starter
Pro
Joined: Nov 2005
Posts: 609
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From: Ontario
No it will not. It will basically split the electrical system, normal path for the car, new path for the fans. Only issue is you will not have current monitoring for the fan circuit, but thats really a non issue. As long as the fan circuit is protected with a fuse of some sort.
Where did you tie in the hot for the fans?
Where did you tie in the hot for the fans?
If I wire the fans to the back of the alternator and "split the electrical system" will the alternator provide enough current for both? I thought that the amount of current generated was controlled by the 2 wires of the "sensing circuit". Or am I wrong?
Thanks.
Dave
Le Mans Master
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Posts: 9,192
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From: Boca Raton Florida
It will not affect the alternator at all, it is providing the current for everything now as it will when you change it. The only thing that is changing is that the fans will no longer draw current thru the battery charge wire. It will also ensure that the fans get full alt voltage and run at full speed.
Thread Starter
Pro
Joined: Nov 2005
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From: Ontario
It will not affect the alternator at all, it is providing the current for everything now as it will when you change it. The only thing that is changing is that the fans will no longer draw current thru the battery charge wire. It will also ensure that the fans get full alt voltage and run at full speed.
I'll give it a try.
Dave
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Thread Starter
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From: Ontario
It will not affect the alternator at all, it is providing the current for everything now as it will when you change it. The only thing that is changing is that the fans will no longer draw current thru the battery charge wire. It will also ensure that the fans get full alt voltage and run at full speed.
OK. I am running a #10 wire from the alternator directly to the circuit breakers that feed the electric fans.
Would I need to run a larger ground wire to the alternator? The stock ground now looks awful small compared to all the hot leads coming off of the alternator.
Dave
Le Mans Master
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From: Boca Raton Florida
A better ground for the alternator is a good idea, just add in a new wire to the ground stud and attach the other end to the block or the frame. I think GM figured on useing the mount brackets as part of the ground system, but thats a pretty poor ground sometimes. The existing ground wire goes back to the battery, which is ok for the charging circuit, but maybe not for a high current device up front.
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
6' and I would probably agree, the ground from your engine to frame under the pass side engine mount to frame.....is enough, it better BE there, and in good shape also....any doubts, just remove and polish up everything and rebolt...same for negative batt to ground/frame under the battery box...one of the very first things I did some 12 years ago when buying the car....that ground wire is primarily for lighting up front...I rerouted mine to the frame, but that's just me....
Thread Starter
Pro
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From: Ontario
A better ground for the alternator is a good idea, just add in a new wire to the ground stud and attach the other end to the block or the frame. I think GM figured on useing the mount brackets as part of the ground system, but thats a pretty poor ground sometimes. The existing ground wire goes back to the battery, which is ok for the charging circuit, but maybe not for a high current device up front.
SIXFOOTER, I have now added a #10 wire from the ground terminal on the alternator down to the frame.
mrvette, yes the ground from the engine to the frame is there and is in good shape. It's brand new. That's one of the first things that I did when I reinstalled the engine - install a new ground cable.
Thanks again.
Dave
Pro
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From: Nice Lake Ontario
So I decided to rip the whole thing out and rewire it with a pair of relays and temperature switches, simple and old school.
Mollyd: thinkin of going the same route, would it be possible to post the part brand & numbers for the switches & relay? When you walk into an automotive around here & ask for something you get the typical blank stare & "What's it out of??"
Mollyd: thinkin of going the same route, would it be possible to post the part brand & numbers for the switches & relay? When you walk into an automotive around here & ask for something you get the typical blank stare & "What's it out of??"
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
IMO, the easiest and best source for wiring harness parts/plugs for relays and fan controlls is a junkyard, off most any GM car with fans....
I choose the older black square style relays/plugs, because I have NEVER seen a bad one, the more modern gray rounded/oval things I have seen multiple failures on, and it sometimes takes the associated plug/harness with it......
look around you will see what I mean....
I choose the older black square style relays/plugs, because I have NEVER seen a bad one, the more modern gray rounded/oval things I have seen multiple failures on, and it sometimes takes the associated plug/harness with it......
look around you will see what I mean....
Thread Starter
Pro
Joined: Nov 2005
Posts: 609
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From: Ontario
So I decided to rip the whole thing out and rewire it with a pair of relays and temperature switches, simple and old school.
Mollyd: thinkin of going the same route, would it be possible to post the part brand & numbers for the switches & relay? When you walk into an automotive around here & ask for something you get the typical blank stare & "What's it out of??"
Mollyd: thinkin of going the same route, would it be possible to post the part brand & numbers for the switches & relay? When you walk into an automotive around here & ask for something you get the typical blank stare & "What's it out of??"
All parts were purchased thru Summit.
185 ON/ 175 OFF fan relay kit #SUM-890015 - $45.95
200 ON/ 185 OFF fan relay kit #SUM-890016 - $45.95
I installed the 185 ON/ 175 OFF switch in the passenger side head and wired the relay to on fan.
I purchased a new water neck with a 1/2" NPT port #TRD-9468 ($9.95) and installed the 200 ON/ 185 OFF switch in it and wired this relay to the second fan.
I purchased the kits from Summit since theirs came with circuit breakers where other kits I have seen use fuses.
BTW: SIXFOOTER and mrvette now that I have wired the fans directly to the alternator they run just great and do not affect the ammeter when they are running. Thanks.
Dave
Le Mans Master
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Here's how I wired it....
I like going to the battery because it softens the surges on the alt but that's just me.
If you are using a temp switch (that goes to a ground for on) just tap onto the wire of #85. This way you can run the fans if the sender goes south or if you want to keep the motor cool (at the dragstrip). AND if you forget to turn the switch on- fans will still come on when temp get to switching temp.
Part # for the relay -12 VDC Tyco Relay SPDT(Single Pole Double Throw) 30A (Formerly Bosch #0 332 209 150 )
Yes-it's now aTYCO relay.... Relay should cost less than $5.
And any switch that's a single pole-toggle switches will work fine-they are only switching a small amout of power-so you don't need a heavy duty one.
Richard
I like going to the battery because it softens the surges on the alt but that's just me.
If you are using a temp switch (that goes to a ground for on) just tap onto the wire of #85. This way you can run the fans if the sender goes south or if you want to keep the motor cool (at the dragstrip). AND if you forget to turn the switch on- fans will still come on when temp get to switching temp.
Part # for the relay -12 VDC Tyco Relay SPDT(Single Pole Double Throw) 30A (Formerly Bosch #0 332 209 150 )
Yes-it's now aTYCO relay.... Relay should cost less than $5.
And any switch that's a single pole-toggle switches will work fine-they are only switching a small amout of power-so you don't need a heavy duty one.
Richard
Last edited by Richard454; Jul 3, 2007 at 11:27 AM. Reason: part #
Le Mans Master
Joined: Jan 2006
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From: Boca Raton Florida
Alternator to #30 instead of the battery. You can also use a thermo switch instead of the on/off switch to make it automatic, the rest is the way I would go for a relay install, you can do that for $10 or $12
Le Mans Master
Joined: May 2003
Posts: 8,876
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Here you go.... BUT either Battery or Alt as your power source- Make SURE you use a fuse (20A will work). I like them over the circuit breakers.....
Richard
Richard
Burning Brakes
Joined: Jul 2001
Posts: 853
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From: Foxfield, Co
I think you will need a fuse bigger than 20 amps for dual spals. Mine draw 10 amps each when running-- 20 total. During a "hard" start like with a relay a electric motor will draw much more current than its normal running current for a second or so. I had to fuse my fans at 20 amps apiece so they dont blow at fan start up.
Greg.
Greg.
