Electric fan question
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 1,139
Likes: 109
From: B'ham Alabama
Electric fan question
My car has dual electric fans that operate off a thermostat relay in the radiator. I recently replaced all my A/C components and I need the fan to run all the time. Can I simply “bypass” the thermostat relay in the radiator and make the fans run all the time?
if so, will that cause any issues letting them run all the time?
if so, will that cause any issues letting them run all the time?
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 1,139
Likes: 109
From: B'ham Alabama
Cruising
Joined: Aug 2017
Posts: 12
Likes: 3
From: Texas
The idea is to use the wire that energizes the compressor clutch. Depending on where have the current relay setup installed, you can tap into it near the compressor or follow the wire back to the firewall and get it from there instead. What kind of setup do you have now? Some have an A/C trigger wire already molded into it. If not, you may have to create your own bypass with an additional relay, but it’s not hard to do. So, post up your current fan controller name/model and someone else can take it from there if I’m not able to post up a diagram. Good luck.
Race Director
Joined: Mar 2017
Posts: 11,947
Likes: 4,506
From: Virginia
I'm going to start by making a bunch of assumptions: You have the dual Spal kit from DeWitts, are using their wiring harness, and followed their instructions to install it.
If that's the case, the thermostat acts as a switch to ground, to complete the circuit that energizes the relay actuation coil(s) (low-current) in the relay(s) that power the fan (high current, 30 Amps).
I don't want to post their IP on this forum, but the DeWitts instructions have a nice diagram of what I just described:
https://www.dewitts.com/pages/information
Click on "Spal Wiring" at the above link.
In that diagram is an optional switch for manual operation of the fans. It, too, grounds the coil in the relay, just like the thermostat. The most facile way to do this would be to bypass (short) the thermostat, causing the fan to run any time ignition power is applied to relay coil. That would be a 60 Amp load on your electrical system all the time. A better, but still very simple, way to do this would be to add the suggested optional switch.
The money way to do this would be to replace the optional switch with another relay, one that is normally open, and closes to ground when the AC clutch power is applied.
If that's the case, the thermostat acts as a switch to ground, to complete the circuit that energizes the relay actuation coil(s) (low-current) in the relay(s) that power the fan (high current, 30 Amps).
I don't want to post their IP on this forum, but the DeWitts instructions have a nice diagram of what I just described:
https://www.dewitts.com/pages/information
Click on "Spal Wiring" at the above link.
In that diagram is an optional switch for manual operation of the fans. It, too, grounds the coil in the relay, just like the thermostat. The most facile way to do this would be to bypass (short) the thermostat, causing the fan to run any time ignition power is applied to relay coil. That would be a 60 Amp load on your electrical system all the time. A better, but still very simple, way to do this would be to add the suggested optional switch.
The money way to do this would be to replace the optional switch with another relay, one that is normally open, and closes to ground when the AC clutch power is applied.
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 1,139
Likes: 109
From: B'ham Alabama
I'm going to start by making a bunch of assumptions: You have the dual Spal kit from DeWitts, are using their wiring harness, and followed their instructions to install it.
If that's the case, the thermostat acts as a switch to ground, to complete the circuit that energizes the relay actuation coil(s) (low-current) in the relay(s) that power the fan (high current, 30 Amps).
I don't want to post their IP on this forum, but the DeWitts instructions have a nice diagram of what I just described:
https://www.dewitts.com/pages/information
Click on "Spal Wiring" at the above link.
In that diagram is an optional switch for manual operation of the fans. It, too, grounds the coil in the relay, just like the thermostat. The most facile way to do this would be to bypass (short) the thermostat, causing the fan to run any time ignition power is applied to relay coil. That would be a 60 Amp load on your electrical system all the time. A better, but still very simple, way to do this would be to add the suggested optional switch.
The money way to do this would be to replace the optional switch with another relay, one that is normally open, and closes to ground when the AC clutch power is applied.
If that's the case, the thermostat acts as a switch to ground, to complete the circuit that energizes the relay actuation coil(s) (low-current) in the relay(s) that power the fan (high current, 30 Amps).
I don't want to post their IP on this forum, but the DeWitts instructions have a nice diagram of what I just described:
https://www.dewitts.com/pages/information
Click on "Spal Wiring" at the above link.
In that diagram is an optional switch for manual operation of the fans. It, too, grounds the coil in the relay, just like the thermostat. The most facile way to do this would be to bypass (short) the thermostat, causing the fan to run any time ignition power is applied to relay coil. That would be a 60 Amp load on your electrical system all the time. A better, but still very simple, way to do this would be to add the suggested optional switch.
The money way to do this would be to replace the optional switch with another relay, one that is normally open, and closes to ground when the AC clutch power is applied.
i just refurbished the A/C system and now need the fans running as soon as I turn the A/C on.
The diagram you attached is exactly what I needed.
Thanks so much!!
Vet76te
Race Director
Joined: Mar 2017
Posts: 11,947
Likes: 4,506
From: Virginia
Thanks Bikespace!! Yes, I’m running Dual SPAL fans on a Dewitt aluminum radiator. I didn’t install them, the car was set up this way when I bought it. Runs super cool!!
i just refurbished the A/C system and now need the fans running as soon as I turn the A/C on.
The diagram you attached is exactly what I needed.
Thanks so much!!
Vet76te
Please keep us updated when you get it to work!
