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View Full Version : C950, air conditioning, and fan control question



Chad-1stGen
05-10-2010, 07:41 PM
So after 3 years I finally got around to finishing the A/C side of my vintage air installation.

I got the hoses crimped today and the system charged and everything appears to actually work on the first run through.

However, I overlooked one "minor detail" lol. I use an electric fan controlled via relay by the Holley Commander 950 ECU. I need the fan to switch on whenever the A/C is on otherwise the system pressure spikes to dangerous levels.

Is there a way to keep the C950 control of the fan and have it turn on when the A/C is on? Do I have to run two relay set ups to accomplish this? It appears the C950 controls the fan via ground while I need to be able to switch the fan on using 12V as well. So I don't think I can just run the ac signal wire in parallel with the ECU signal wire.

Anyone?

Chad-1stGen
05-11-2010, 06:47 AM
Man I hate doing things backwards lol!!

Seems what I should of done is picked up a trinary switch to replace the binary switch that comes with the kit and used that to control the fan for AC. That way it isn't on 100% of the time the AC is in situations like on the freeway/high speed.

Looks like I get to have them recharge the system. arrrgggh

Still not sure if I can get away with using one relay or need two though.