Vintage air, radiator cooling fans - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**General23cmp** · 12-29-2020, 07:36 PM

Who here has Vintage Air, and what did you do for you electric fans? I know a guy that has this, and he said he had to keep his dual fans on high to avoid excessive head pressure. That’s certainly doable, but I’m not sure how his is set up and the quality of his fans.

Do you normally have your low fan setting turn on one of the two fans at high speed or do you have both come on at a low speed like many LS cars had (high would be both at high speed....this is done with three relays)? What do you have happen when the AC turns the fans on (one fan or two, high speed or low?)?

Thanks.

ls1nova71 · 12-30-2020, 06:06 AM

The high and low fan speeds are controlled by the PCM based on engine temperature. For A/C, the fans should be controlled by a trinary switch so they come on based on head pressure. They need to come on high as there is only one setting that they will come on, so if you set them to come on low, if that isn't enough there would be no way to trigger the high speed.

**nsb29** · 12-30-2020, 09:10 PM

I have duel fans controlled by the ecm and three relays both fans run on low speed or high depending on temperature for the a/c I have a binary switch and a high pressure transducer Which will allow the ECM to see the pressure of the AC system so that it can stage the cooling fans accordingly bump the idle and calculate load this is how all LS equipped vehicles operate in factory form

**General23cmp** · 12-30-2020, 10:19 PM

Quote:

Originally Posted by nsb29

I have duel fans controlled by the ecm and three relays both fans run on low speed or high depending on temperature for the a/c I have a binary switch and a high pressure transducer Which will allow the ECM to see the pressure of the AC system so that it can stage the cooling fans accordingly bump the idle and calculate load this is how all LS equipped vehicles operate in factory form

Is your AC compressor factory LS style or Vintage Air Sanden? What year LS did you use, and do you recall if the ECM needed a ground or 12v on the pin that tells it that the AC is on? Some LS engines use 12v and some use ground. Mine is an 02 LQ9.

**nsb29** · 12-31-2020, 08:56 AM

The compressor is Sanden, as for the transducer there are three wires that go to it, harness is from BPautomotive I have no idea what pin or pins they go to.
The engine is out of a 2009 Pontiac G8 L76

**paul mora** · 12-31-2020, 12:19 PM

If you bought the widening harness from BP give them a call the tech support can answer all you questions

**1971Stepside** · 12-31-2020, 02:33 PM

I put the inline pressure switch in and use a binary switch along with dual fans on the Entropy radiator.

12-29-2020, 07:36 PM	#1
General23cmp Senior Member Join Date: Mar 2016 Location: Athens, AL Posts: 360	Vintage air, radiator cooling fans Who here has Vintage Air, and what did you do for you electric fans? I know a guy that has this, and he said he had to keep his dual fans on high to avoid excessive head pressure. That’s certainly doable, but I’m not sure how his is set up and the quality of his fans. Do you normally have your low fan setting turn on one of the two fans at high speed or do you have both come on at a low speed like many LS cars had (high would be both at high speed....this is done with three relays)? What do you have happen when the AC turns the fans on (one fan or two, high speed or low?)? Thanks.

12-30-2020, 06:06 AM	#2
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,119	Re: Vintage air, radiator cooling fans The high and low fan speeds are controlled by the PCM based on engine temperature. For A/C, the fans should be controlled by a trinary switch so they come on based on head pressure. They need to come on high as there is only one setting that they will come on, so if you set them to come on low, if that isn't enough there would be no way to trigger the high speed. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

12-30-2020, 09:10 PM	#3
nsb29 Senior Member Join Date: Feb 2014 Location: new smyrna beach fl / 29 palms cal Posts: 1,727	Re: Vintage air, radiator cooling fans I have duel fans controlled by the ecm and three relays both fans run on low speed or high depending on temperature for the a/c I have a binary switch and a high pressure transducer Which will allow the ECM to see the pressure of the AC system so that it can stage the cooling fans accordingly bump the idle and calculate load this is how all LS equipped vehicles operate in factory form __________________ Hand made A/C vent manifolds for 64-66 trucks adapts any aftermarket A/C to OEM vent

12-31-2020, 08:56 AM	#5
nsb29 Senior Member Join Date: Feb 2014 Location: new smyrna beach fl / 29 palms cal Posts: 1,727	Re: Vintage air, radiator cooling fans The compressor is Sanden, as for the transducer there are three wires that go to it, harness is from BPautomotive I have no idea what pin or pins they go to. The engine is out of a 2009 Pontiac G8 L76 __________________ Hand made A/C vent manifolds for 64-66 trucks adapts any aftermarket A/C to OEM vent Last edited by nsb29; 12-31-2020 at 09:03 AM.

12-31-2020, 12:19 PM	#6
paul mora Senior Member Join Date: Jan 2009 Location: huntington beach california Posts: 976	Re: Vintage air, radiator cooling fans If you bought the widening harness from BP give them a call the tech support can answer all you questions __________________ Pulatoy

12-31-2020, 02:33 PM	#7
1971Stepside Almost Satisfied Join Date: Mar 2002 Location: Springfield, MO Posts: 2,932	Re: Vintage air, radiator cooling fans I put the inline pressure switch in and use a binary switch along with dual fans on the Entropy radiator. Attached Images __________________ 1971 C10 Stepside. LSx 6.0 with BTR Stage IV, Speed Engineering Headers, 4L80e transmission w/3200 Circle-D Stall. 3.73. Posi. Purchased this truck when I was 17. I started the rebuild (or take apart) in 1993. I have drug it around all over the country in pieces. Finally back on the road in 2021. "I can't complain, but sometimes I still do. Life's been good to me so far."



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