Electric fan swap on the cheap

kennythewelder

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I bought a set of electric radiator fans at pull-a-part, I got them off of a 2004 Cadillac DTS. They were about $30 with tax. I messed up, and also got a relay block with only 4 relays, it was $25 as they charged me for a fuse block with relays. I thought this was high,but had I bought 4 separate relays with the connectors, it would have been about the same price, so oh well. I started digging though my junk boxes in my shed, and found plenty of wire to connect everything. I wired 2 of the relays ( one for each fan) and I activate these relays with a toggle switch on the dash. This is wired on an ignition switched wire, so that the fans go off when the key is turned off. I have a thermo switch on a bung welded to the thermostat housing. The switch fits a BMW from the mid 1970s. although the one in the pics is the first one I tried from E-bay. It was cheap junk and I had to replace it. I bought an extra housing to do this with. This trips the relays so the fan comes on at 190 F, and off at 175 F. I have a 170 degree thermostat in my truck. I tapped into the AC compressor positive wire for the compressor clutch, and tied this into a 3ed relay. I tied this relay into the trip wire for the other 2 relays so that when the AC compressor kicks on , the fans will turn on also, but will not back feed the AC compressor so that the compressor would not come on when the fans come on from another source. I ran 8 gauge wire to power the fans, and some small wire to trip the relays, about 14 gauge. I went to a local automotive audio shop and bought 2 large blade fuse holders for my positive supply wires. They were $10, All of the relay switch wires are fused, from the source where I tided them in. I took the set up to work, and built some custom stainless steel brackets to hold everything in place. I used the OE bolt holes that held the old fan shroud for the new stainless brackets that I fabbed up. I also had to do a little trimming on the DTS fan shroud to make the SST brackets fit them securely. Although the DTS shroud is about 4 inches shorter then the OE truck shroud, I just added a small piece of foam insulation to hold the DTS fan shroud off of the radiator a bout 1 1/2 inch so that air from the bottom 4 inchs of the truck radiator, had a way to flow. It seams to all work well. So all of this cost me about $75. Keep in mind I had all of the wire laying around, and I am a certified welder. We do a lot of stainless steel work at the shop where I work. I have access to all of the equipment need to pull off a job like this. I used scrap stainless steel we had in the scrap bin. I also soldered and used heat shrink on all of the connections, except for the wire lugs I need to make the connections for power supply, or grounds, and I used some old copper line I had laying around to make the big lugs by flattening one end, and drilling a hole on that side. I also zip tied and used silicone to mount the relays in place. I do have the big 3 up grade, but I added 2 extra grounds, so a big 5 up grade I guess. One at the cab of the truck, and one at the frame. I did that many months ago for my amp and sub set up. I have had the fans in the truck for about 3 months now, and it works grate. A little more power at higher RPMs, and the AC stays cold with in town driving.Here are the pics.20180519_183034.jpg20180520_151046.jpg 20180525_105440.jpg 20180530_201051.jpg 20180529_102741.jpg
 
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kennythewelder

Officially Retired, B31-3 (6 G ) certified
Joined
Aug 13, 2018
Posts
359
Reaction score
182
Location
Louisiana
Before pics, and in the last pic, you can see I welded 2 bolts back to back so I could install the extra connections to the battery.20180121_172806.jpg 20170304_134004.jpg 20170820_171958.jpg
 

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