Fan control help please

[GMJim]

Hello and thanks in advance for any help anyone can give me. I have a 68 Chevy C10 with a stock 4.8 out of a 2002 Chevy Silverado and a Painless engine harness with a 12200411 PCM. I set both fans to come on at 205 degrees and off at 195 and that may have been a mistake. While checking to make sure the computer was grounding fan 1 and fan 2 i found a strong ground on fan 1 but a weak pulsing ground on fan 2. Could anyone suggest what thermostat I should use and what temperature the fans should be set at and maybe help with why the fan 2 ground signal from the computer is weak and pulsing?
Thanks
Jim

[Jason B]

Need to set fan type fitted to analog, etc, etc. Maybe post your tune.

[GMJim]

Can't post my tune as it's in a friends computer. Tune is stock though. Aftermarket electric Spal fans.
Thanks

[IARLLC]

Sounds like a fun project. I will never forget the 68 stepside I took 9 years to build

The file I attached if offered by one of the very popular e-fan harness sellers. The rest of the tune is not useful. I would just copy over the fan information from it. But raise the fan disable speed to 25 mph or so.

Also, does your harness have 2 or 3 relays to control fans? The 2 relay systems control the fans separately. The 3 relay systems control them together allowing both at low speed (though fan #1) and both at high speed (through fan #2).

[GMJim]

Sounds like a fun project. I will never forget the 68 stepside I took 9 years to build

The file I attached if offered by one of the very popular e-fan harness sellers. The rest of the tune is not useful. I would just copy over the fan information from it. But raise the fan disable speed to 25 mph or so.

Also, does your harness have 2 or 3 relays to control fans? The 2 relay systems control the fans separately. The 3 relay systems control them together allowing both at low speed (though fan #1) and both at high speed (through fan #2).

Thanks for the info. I'll load the file when I get a chance. The fans are not GM fans and not two speed fans. My plan was to have both of them to come on at the same time and I was going to use the fan 1 wire and the fan 2 wire from the computer on separate relays but because the fan 2 wire wasn't grounding properly I'm hesitant to try to use it. I didn't realize I could disable them at a certain speed? That would be very helpful. I'll have to look for that and set it.
Thanks

[IARLLC]

Most of the settings to change are under System>Fans but Jason B was right, under System>AC you need to make sure that Recirculation Fiitted is switched to Fan #2, and Type Fitted is switched to Analog Cycl. That will get your blue wire from your red connector #33 to provide a solid ground for Fan #2. You can just copy those settings from the file I sent.

As far as fan layouts. Of course you can run them separate as fan #1 and fan #2 (kicking in #2 at higher temps) or if you run a 3 relay set-up (like GM has been doing on F-bodies since the 90s and on trucks since 2005) you can run normal (one speed) fans at half speed (wired in series through the extra relay) and full speed (parallel). I really like it. At half speed I cannot even hear them and they pull more air than a big old clutch fan at idle. If you are interested in that idea I can post a GM diagram I prefer.

[GMJim]

Most of the settings to change are under System>Fans but Jason B was right, under System>AC you need to make sure that Recirculation Fiitted is switched to Fan #2, and Type Fitted is switched to Analog Cycl. That will get your blue wire from your red connector #33 to provide a solid ground for Fan #2. You can just copy those settings from the file I sent.

As far as fan layouts. Of course you can run them separate as fan #1 and fan #2 (kicking in #2 at higher temps) or if you run a 3 relay set-up (like GM has been doing on F-bodies since the 90s and on trucks since 2005) you can run normal (one speed) fans at half speed (wired in series through the extra relay) and full speed (parallel). I really like it. At half speed I cannot even hear them and they pull more air than a big old clutch fan at idle. If you are interested in that idea I can post a GM diagram I prefer.

Thank you very much! I would very much like to run the fans at a lower speed. These fans move a lot of air at full speed. Sometimes I think the fans alone would pull the truck down the road LOL. You could post the diagram or e mail it to me if you wish. I'll print your post so I can follow Jason B's and your explanation on the settings.
Thank you both very much for the help!
Jim

[IARLLC]

This is my favorite way to set them up. I think it is from an F-body. There is a very small difference on the newer trucks but it does not matter. Enjoy!
Jeff

[GMJim]

This is my favorite way to set them up. I think it is from an F-body. There is a very small difference on the newer trucks but it does not matter. Enjoy!
Jeff

Jeff
Thanks a bunch! Do you have any suggestions for the thermostat temp and what to set the fans up at?
Jim

[IARLLC]

Well on the trucks the factory thermostat does not let the engine go much below 195 so I turn the low fan off by 197...or it might run all of the time. The temps on the "fan patch" file I posted work pretty well but you might like to lower the high fan temps by 5 degrees or so.

I know a lot of people like to run the 160 stat for performance but it is a little bit cold for me. I prefer a high flow 180 stat. If you run a 180 you can pretty much take all of the temps on that fan patch and lower them 10-12 for a nice result.

[GMJim]

Well on the trucks the factory thermostat does not let the engine go much below 195 so I turn the low fan off by 197...or it might run all of the time. The temps on the "fan patch" file I posted work pretty well but you might like to lower the high fan temps by 5 degrees or so.

I know a lot of people like to run the 160 stat for performance but it is a little bit cold for me. I prefer a high flow 180 stat. If you run a 180 you can pretty much take all of the temps on that fan patch and lower them 10-12 for a nice result.

Jeff
Thanks for the suggestions! I'm going to try to get this set up in the next week or so. You've been a great help, I'll let you know how it goes!
Jim

[IARLLC]

Jim
Real glad to hear it. Just thinking about it brings back so many good memories of my 68 Stepside. Those are some of the best looking trucks ever. Coupled with today's LS motorvation and tech, all good! Will look forward to hearing about it.
Jeff

[IARLLC]

One quick thing to add, after doing a few of these e-fans I noticed something that is NOT in the patch file I posted...that IS in a stock 2005 file. Under Engine>Idle>Airflow>Cooling fan airflow 2005 stock truck/suvs have 2.0 lb/h for Fan 1 and 4.4lb/h for Fan 2. This helps a bit with the extra drag/bump from the alternator when the fans kick in. I just added it to my tune and all of the clients' tunes that I have done this swap for....now to call them to stop by for a slight improvement. I suppose that I need to make these and a few other minor changes to the patch files before posting them anymore. The patch file did not originate with me but if I am passing them around they should have all that suits an e-fan retrofit.

OK. I just made a new "Fan Patch" file with the suggested airflow changes for fan electrical drag. I also made small changes to Start-up Airflow Initial on the same page and Spark Start-up Flare Control as they seem to spring to life a bit more freely without the clutch fan drag.

[GMJim]

One quick thing to add, after doing a few of these e-fans I noticed something that is NOT in the patch file I posted...that IS in a stock 2005 file. Under Engine>Idle>Airflow>Cooling fan airflow 2005 stock truck/suvs have 2.0 lb/h for Fan 1 and 4.4lb/h for Fan 2. This helps a bit with the extra drag/bump from the alternator when the fans kick in. I just added it to my tune and all of the clients' tunes that I have done this swap for....now to call them to stop by for a slight improvement. I suppose that I need to make these and a few other minor changes to the patch files before posting them anymore. The patch file did not originate with me but if I am passing them around they should have all that suits an e-fan retrofit.

OK. I just made a new "Fan Patch" file with the suggested airflow changes for fan electrical drag. I also made small changes to Start-up Airflow Initial on the same page and Spark Start-up Flare Control as they seem to spring to life a bit more freely without the clutch fan drag.

Thanks
Copied for later!

[GMJim]

Well..........I finished the wiring today and tested things out. Everything worked great for a while then I noticed a smell of burnt paint. I shut everything down and while looking and feeling around I noticed the fan motors were very hot. Checked the wiring again and it was all was done correctly. I called Spal and had quite a conversation about wiring. He said Spal fans aren't like factory fans and are wound to operate within 10% of battery voltage. He said he was very familiar with the 3 relay setup running in series but warned against doing it. I rewired the fans to operate individually and they seem to be running very much cooler. Running one fan in initial cooling seems to be easier on the charging system and when things get hotter the other one comes on.

Thanks very much for the advice to get fan 2 running though. Much appreciated help!
Jim

[IARLLC]

Hi Jim,
Thanks for letting us know about that. Seems strange that the motors would get hot running at half voltage but Spal certainly knows their stuff. I don't doubt their word.

All the best!
Jeff

[GMJim]

Hi Jim,
Thanks for letting us know about that. Seems strange that the motors would get hot running at half voltage but Spal certainly knows their stuff. I don't doubt their word.

All the best!
Jeff

Jeff and Jason B, thanks for the help. I did tech support for our company (Hurst Driveline formerly Classic Motorsports Group) and can tell you getting help on a subject you've had little or no experience with from hands on people is the best!
Jim

[tnbubba]

hope somebody sees this... what is the difference in the serial cycling vs analog cycling.. hp just says type of ac fitted to vehicle... so?? yes i have the fan retrofitted fabout 8-10 yrs ago and ran a BB tune until i got hp tuners fans have never worked like i thought they should

[RDF1]

How are the fans working now?
Serial is 2 fans and analog is one fan i think? ill have to go dig up one the older tunes.

[tnbubba]

How are the fans working now?
Serial is 2 fans and analog is one fan i think? ill have to go dig up one the older tunes.

no its the communication to the pcm serial uses buss thru the BCM and analog is just fed stright to pcm
if you dont get htose right then youfan programmign is screwed anyway on the 2nd speed ac fan..tooks some digigin and lookgin at wirint diagrams to figure that out.