Pin 33 not activating high speed E-fan.

[mchj74]

So, after swapping to Eletric I can activate them through the scanner with no problem. They come on at temp at low speed but, when I turn on the A/C the high-speed fan does not come on it stays at low speed. What am I missing here are my settings.

Fan type 2

fan 1
on ECT 200
Off ECT 192

fan 2
On ECT 210
Off ECT 199

Recirculation fitted fan#2
Type Fitted Analog cyclin

[HATEHPTUNERS]

You do not mention what year your vehicle is, HOW you have the A/C set up-are you running a pressure sensor? These are the things we need to know.. Is this a swap vehicle? Variable or fixed rate A/C compressor? Hi/Low pressure switches......? there is so much information that is needed to get you on the right path. Without a GM pressure sensor, or a Trinary switch from someone like Vintage Air-your PCM will NOT command Hi speed fan operation..... I guess I could have just started with that..

[mchj74]

Sorry, I'm new to this its a 2002 silverado all stock A/C. It has the stock 2 wire pressure switch. Do I need to upgrad it to the 2004 & up pressure sensor?

[Alvin]

Have you tried grounding the two pins going to the ECM to see if the harness is OK?

Green is low

Green and blue both grounded = high

[mchj74]

The harness is good

[mchj74]

Any one have any ideas?

[2xLS1]

https://www.performancetrucks.net/fo...ontrol-553385/

[HATEHPTUNERS]

You will need to add either the GM pressure sensor, OR a trinary switch such as what vintage air sells IF YOU WANT THE PCM TO CONTROL HIGH SPEED FAN OPERATION WHEN THE A/C IS ON. Please note that either of those two options *may* require cutting into an existing high pressure hose for the a/c system so that you can add the piece that the sensor threads into/onto. Your vehicle, from the factory, utilizes the low pressure switch as a cycling switch, and potentially a high pressure switch as well to shut the compressor off in the event of a high pressure situation. Your system is NOT set up to control high speed fan operation based on pressure from the a/c system The pressure sensor will solve this problem.

There are other easier ways to do this, but they come with their own set of draw backs, or compromises if you will. You can have the high speed fan come on anytime the compressor is commanded on... but that method will have the high speed fan running ANY TIME the a/c is on and that means even at 65+mph going down the freeway when you DO NOT WANT IT ON. But... it will solve your no high speed fan with a/c situation without hacking into the wiring, and reprogramming the PCM.

[Alvin]

The harness is good

The first post.. Sounds like when you command high with the scanner they do not go to high. This tells me something might not be right with the harness.