AC trigger wire for electric fans
06-29-2007, 07:47 AM
#11
I have the Nelson Harness and I reccomend either putting the Higspeed Mode a manual switch or Wiring it so highspeed can be turned on by both the AC/PCM and a Manual switch...
The reason i say a manual switch is because in stop an go traffic the fans won't be on high unless the AC is on, i don't run my AC much so by doing this my Engine temps stay right at 179-185 degrees in even the worse traffic.
Now do rmember that if you only wire a manual switch for highsped you NEED to turn the fans on to high speed if you run the AC... I am working on rewiring the harness with a Double through relay to run both Manual and AC control for the fans, I am going to the surplus store this weekendto look for a relay.
The reason i say a manual switch is because in stop an go traffic the fans won't be on high unless the AC is on, i don't run my AC much so by doing this my Engine temps stay right at 179-185 degrees in even the worse traffic.
Now do rmember that if you only wire a manual switch for highsped you NEED to turn the fans on to high speed if you run the AC... I am working on rewiring the harness with a Double through relay to run both Manual and AC control for the fans, I am going to the surplus store this weekendto look for a relay.
06-29-2007, 09:20 AM
#12
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If you hook up pin 33, you can program the hi speed fans to come on 5 degrees above the lo speed temps to keep it cool and drop the a/c pressure turn it on earlier and then you don't need a manual switch. I rewired the Nelson 3 relay harness to work on pin 33 and it works like factory. Works on 03 and later.
06-29-2007, 09:44 AM
#13
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To run a (-) trigger on the 3rd relay (the high speed circuit in the diagram I have) you just need to swap the +/- on the trigger side of the relay (NOT on the load side).
However, since I have HPT, doesn't fan 1 turn it on at low speed and fan 2 setting turn on the high speed???
Which wire is the AC compressor wire? That's the one I really want since I don't have another pin to add to the factory harness. All I want to do is have the fans come on high with the AC only.
However, since I have HPT, doesn't fan 1 turn it on at low speed and fan 2 setting turn on the high speed???
Which wire is the AC compressor wire? That's the one I really want since I don't have another pin to add to the factory harness. All I want to do is have the fans come on high with the AC only.
06-29-2007, 10:21 AM
#14
Originally Posted by bluecajun5.3
so instead of tapping into the a/c wire, use that wire to tap into pin 33 on the pcm? i get agrivated when my compressor turns on and the fans turn on high when it does. i would like them to stay on high all the time when the a/c is on high. and my tuner uses efilive.
BigRedExpress99 got it to work
https://www.performancetrucks.net/fo...blowing+relays
and here
http://forum.efilive.com/showthread....highlight=efan
PN# for the GM relay setup 15216055
06-29-2007, 03:41 PM
#15
Originally Posted by truckmann
There are no A/C control setting for the fans in HP Tuners currently. Only Fan 1 and Fan 2 on/off temp settings. There is a request to add the A/C control features on the message board so hopefully they will add it.
http://www.hptuners.com/forum/showth...2923#post92923
Anyone with HPT that is interested in these features post up over there and maybe that will give them incentive to add them.
http://www.hptuners.com/forum/showth...2923#post92923
Anyone with HPT that is interested in these features post up over there and maybe that will give them incentive to add them.
06-29-2007, 03:45 PM
#16
and its the solid green wire under the a/c compressor relay on the fuse box. not the green white. the green/white is looking for a ground and if you hook up to that one you will cause the compressor to stay on ALL the time. i know, i did it. i went by the wrong diagram.
Last edited by 4.8T; 06-29-2007 at 03:53 PM.
06-30-2007, 10:47 AM
#17
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Originally Posted by 4.8T
and its the solid green wire under the a/c compressor relay on the fuse box. not the green white. the green/white is looking for a ground and if you hook up to that one you will cause the compressor to stay on ALL the time. i know, i did it. i went by the wrong diagram.
07-07-2007, 06:40 PM
#19
Originally Posted by BlackGMC
I believe pin 33 only works on 03+ trucks. From what I have read if you use the AC trigger wire then the fans will cycle on and off each time the compress cycles on and off. If you use the PCM pins 42 and 33 you have much more control escpecially if you have the fans programed with EFI Live, I don't know if HP tuners allows you to control the fans according to AC pressures.... Perhaps someone with HP tunners can comment...
EFI Live settings
EFI Live settings
