View Full Version : Help needed with my cooling fan.
Randy's
12-29-2023, 03:12 PM
I have a BPE 347 with a Holley Sniper. There are two CTS installed. One drives the temperature guage on the dash. The other turns on the cooling fan. When the temperature guage shows 80 degrees celcius, the fan kicks on. Both the guage and the fan have worked flawlessly for the 6,000 miles I've put on the car. However, last weekend while driving, my temperature guage hit 80, then 90 then close to 100. I pulled over and turned off the car. It was then that I determined the cooling fan did not turn on. I let it cool and got it home with no issues. I ran power direct to the fan and it worked, so I think the fan is good. I figured the sensor is bad. I installed a new one, got the car up to temperature but the fan is still not coming on. I opened the Holley Sniper screen to make sure the "fan on" and "fan off" settings are good. So I have done all I know to do. Any help or suggestions you can give will be most appreciated.
Check the fan fuse and the relay.
Randy's
12-29-2023, 04:31 PM
Papa, I forgot to mention that I checked the fuse. However, I forgot about the relay. I will change that and see what happens. Thank you!
Papa, I forgot to mention that I checked the fuse. However, I forgot about the relay. I will change that and see what happens. Thank you!
You can test it quickly by swapping the fan relay and the horn relay. If the horn works after they are swapped, it isn't the relay.
Norm B
12-29-2023, 05:29 PM
Try grounding the relay trigger wire at the Sniper to see if the fan comes on.
Norm
I am probably not the person to respond to an electrical problem, but I had the exact same issue. Thought it was in the wiring, or a bad fan unit. It turned out to be the fan relay went bad. Replaced it and knock on wood, I haven't had an issue since. Papa has the right method for determining if that is the problem, just switch the fan and horn relays. I bought an extra to carry with me, figuring that if I did have a replacement, it would never happen again!
egchewy79
12-29-2023, 07:42 PM
Had my fan relay quit a couple of months ago resulting in my lower radiator hose blowing off in traffic. Bought 2 new Bosch relays and good to go.
Nigel Allen
12-30-2023, 01:22 AM
X2 on Bosch relay as a replacement
AC Bill
12-30-2023, 04:04 AM
Good reason to wire a manual override switch for the fan. That was very common on the early FFR's. Temp starts to climb higher than normal, hit the fan switch, and your good to go.
Stangarang
12-30-2023, 05:31 AM
Don't want to sound like a Noob, but what relays are best.
Thanks, Michael
Nigel Allen
12-30-2023, 07:39 AM
Don't want to sound like a Noob, but what relays are best.
Thanks, Michael
Bosch or Hella.
Bill Elliott
12-31-2023, 11:13 PM
Had my fan relay quit a couple of months ago resulting in my lower radiator hose blowing off in traffic. Bought 2 new Bosch relays and good to go.
anyone have a p/n for the bosch relay
There are many part numbers, but I'm using this:
https://www.amazon.com/gp/product/B004Z0VX4S/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Nigel Allen
01-01-2024, 12:12 AM
Papa's on the money
egchewy79
01-01-2024, 10:40 AM
That’s what I used as well. I would recommend swapping the two relays first to make sure that’s the problem, or use a multi meter to check the presumed bad relay before you start throwing money at the problem. I have a manual fan switch in my dash so I was able to check pretty easily. IIRC, the horn relay also runs the fuel pump as well so if you might not be able to simply swap the relays to check if you don’t have an additional fan switch and using an electric fuel pump
That’s what I used as well. I would recommend swapping the two relays first to make sure that’s the problem, or use a multi meter to check the presumed bad relay before you start throwing money at the problem. I have a manual fan switch in my dash so I was able to check pretty easily. IIRC, the horn relay also runs the fuel pump as well so if you might not be able to simply swap the relays to check if you don’t have an additional fan switch and using an electric fuel pump
The fuel pump is on its own relay.
Randy's
01-01-2024, 06:50 PM
Update. I had an extra relay so I tried it. No luck. I swapped the horn and fan relays just to confirm the relay is good. The horn works with both so it's not the relay. The fuse looked fine but I put a new one in. It's not the fuse. Ran power direct to the fan again and it works. It's not the fan. I replaced the CTS so, unless the brand new one is bad, it's not the CTS. I checked all the connections and wiring and saw no issues. I looked on the internet and the Holley forum suggested that I set the "Fan On" temp to zero degrees. Doing this should trigger the fan on at start up. Did that but the fan did not come on. Unless there is something else, I conclude that the Sniper is not receiving the signal from the CTS or it is not sending the signal to trigger the fan to turn on. I'm not sure how to test this as electrical work is not my strong point. I'm always afraid that I am going to "fry" something. I will do some more research. If all else fails, I will wire the fan so I can turn it on with a switch. Again, any suggestions will be appreciated.
What is the Sniper showing for coolant temperature? Are you certain that the new CTS is good? What made you replace it to begin with? Can you verify that the Sniper is completing the ground on the fan control output? Can you confirm that grounding the fan thermo wire activates the fan?
Randy's
01-02-2024, 10:22 PM
Papa, the Sniper hand held monitor temperature got up to 200-205 degrees at which point I turned the engine off. The only reason I replaced the CTS was because I tested the fan, fuse and relay and they were all good. My thinking was that the CTS had to be bad. As far as verifying that the Sniper is completing the ground on the fan control output and confirming that grounding the fan thermo wire activates the fan, I could use some guidance on how to do that. Am I correct in that if I ground terminal #85 on the relay, the fan should turn on? I hope to have some time to work on it this weekend. Thanks again.
Okay - if the Sniper handheld is reading temperature, that's good and means that the CTS is working. Now you'll need to find the connection where the Sniper light-blue fan control wire connects to the green fan thermo control wire. Separate the connection and touch the green wire to a good ground (bolt on the chassis, etc.). If the fan comes on, the fan relay circuit is good. To test the Sniper completing the ground circuit for the fan, get the engine up to temp above the fan setting in the Sniper and check for continuity on the Sniper fan control wire to a good ground point on the chassis. If you have continuity, then the Sniper is working correctly. Now reconnect the Sniper wire to the fan thermo control wire and see if the fan comes on with the coolant above the set temp. If it does, then the connection was probably bad. To check continuity, you'll need a multi-meter. Here is a simple example of how to test for continuity:
https://youtu.be/E9MsyLZF0r4?si=Q-j7sQ_tstc1X-B1
Randy's
01-03-2024, 02:00 PM
Papa, thanks much for the information. I sound like a noob but just to confirm I understand the continuity test, I touch the red multimeter probe to the blue fan control wire and the black multimeter probe to a good ground?
Papa, thanks much for the information. I sound like a noob but just to confirm I understand the continuity test, I touch the red multimeter probe to the blue fan control wire and the black multimeter probe to a good ground?
Correct. You need to do this with the car running ant the coolant temp above the Sniper' fan turn on value.
We want to see if the Sniper is closing the ground like it should. That's what triggers the fan relay to turn your fan on.
Randy's
01-08-2024, 09:13 AM
My fan is now working although I'm not sure what the issue was. I grounded the thermo fan wire and the fan did not come on. I did some additional testing and concluded (right or wrong) that I had a bad connection somewhere in the wiring. I checked all the connections. Unplugged and plugged them back in. I even de-pinned some. No luck. The last thing I did was to unscrew the fuse panel and drop it so I had access to the back side. I pushed and wiggled the connections to the fan fuse and relay, screwed it back in place and now the fan works! Anyone have any ideas on what happened and why?
By identifying that grounding the fan thermo control wire didn't turn the fan on, that indicates that the issue is in the fan wiring circuit. By wiggling wires in the fuse block and getting it to work, that indicates either a loose connection or possibly corrosion in the fuse block. Has the car been rained on or washed where water could enter the fuse block through the windshield openings? If you don't see any corrosion, it is likely a poor contact that could allow the issue to reappear down the road. You could zero in on the specific wire/connection by going back to grounding the fan thermo control wire to turn the fan on and carefully wiggling each wire for that circuit in the fuse block to see if you can get the circuit to open and kill the fan.
Randy's
01-08-2024, 02:05 PM
It has never been rained on but I do wash it regularly. I have grommets around the windshield mounting arms and put silicone around the opening from underneath (not easy to do) but water still gets in. Although I saw no corrosion on the fuse panel, I'm leaning toward that being the issue. I know some mounted the panel elsewhere because of this problem. I have no desire to try to relocate mine but would welcome ideas on how to protect it from water.
ProfessorB
01-12-2024, 11:58 AM
Ummm,Hi
I DO want to sound like a noobie (because I am one)....hi-jacking this thread a little bit. Regarding fan removal (Mark 3) there is a top aluminum "shield at the top of the fan. Since I didn't build the car, I am unsure how to remove this shield so that I can get the fan out. Or am I way off base on my whole strategy?
Can you post a few pictures?