Fan not turning on

[earnies2]

(06-11-2018 )Nilao Wrote:  The prostar will throw a code of you wire the fan to a switch. It monitors the current in the ground side and when you cut the ground wire to splice in the switch the ecm loses the reference voltage and throws the check engine light everytime yo break the circuit.

The only way to do this is to wire in the switch and suppress the code in the ecm program.

so of I am understanding this when the ground is broken the fan turns on or does the BCM/ECM supply the ground to complete the circuit and wiring a switch in would set a CEL.

[earnies2]

(06-11-2018 )Chamberpains Wrote:  So your highest temp is? If its not going above 220 and your not getting check engine lights than its not overheating. Or is it going that high or further?

The reason I ask is because your gauge may be messing with you. It may have always been showing the fan coming on at 200 when in reality its coming on at 210. Maybe now the gauge screwed up again and is showing a different temp. You'll know this once you hook insite up.

There are many things that kick the fan on. Coolant temp, oil temp, intake air temp, a/c pressures.

You can always add an aux manual switch to the fan. The prostar guys may be able to chime in on how to wire it. Some trucks if hooked in wrong will operate the fan but will also throw a check engine light for the fan circuit.

I have a Kevin Rutherford gauge and I just changed it to monitor my coolant temp I only have 15K on the deck and the temp has stayed at 182 I will monitor it today it has matched the gauge sofar....

[earnies2]

(06-11-2018 )Chamberpains Wrote:  If thats the case with cutting into the wiring to your original fan solenoid and you don't want to or don't have means to suppress the code. Then you can always plumb in a "normally open" solenoid after the factory 1's air line that runs to the fan and run your own wiring and switch in the dash.

Thanks for that so normally open means the air supply will flow through and when I activate it it will send air to the fan so there should be 3 ports on the solenoid?

[Chamberpains]

No, normally open means that the solenoid itself is open allowing air to flow through. When you switch it on it will close cutting air off to the fan. Which engages the fan.

You can buy the exact same solenoid that's on your truck now or shop around for a cheaper one. Sometimes they come with three ports. Sometimes with two ports and one exhaust already attached. It all depends on which one you buy. The ones with three ports can usually be configured multiple ways. Normally open or normally closed.

[Nilao]

The ecm supplies the ground. When you interrupted ground you de energize the solenoid allowing the air on the fan side to exhaust from the bottom.

Do not purchase a 2 port. All the have is an inlet and outlet. There is no way to vent the pressure on the fan hub without a exhaust port.

You want a 1/4" 3 port normally open pnuematic valve. Something like https://amzn.to/2LfwCXo

[earnies2]

So if the ECM supply's the ground I just can't put a switch on the dash and supply a ground to the factory solinoid? What about the high pressure switch on the ac does that switch make or break the ground? Just thinking

[Nilao]

The ecm supplies ground to disengage the fan...you would put the switch in the ground circuit to interrupt the ground to turn on the fan. The issue that will arise doing it that way is the fact that the ECM eill wer that loss of voltage and throw a check engine light as it sees that as a faulty solenoid or circuit. If you dont mind a check engine light all the time then by all means do it that way. They only way to be able to make the ground switchable without throwing a code is to suppress the code via c@lt3rm. The simple way is like chamberplains mentioned, add a second solenoid that you control via a switch to release the pressure.

[Chamberpains]

I imagine cutting into the high pressure switch would be another effective way of getting the fan to come on. One way to test if it's going to throw any kind of codes is to Simply unplug it while the engine is running and see if any lights come on.

Just be prepared because most newer trucks tie the air conditioning circuit into cab controllers which throws warning lights and things of that nature. There is also often a minimum run time for the fan when it is engaged for high pressure on the air conditioning. Usually 30 seconds or more or even sometimes it's set to a minimum vehicle speed. So it may not shut off exactly when you command it too because of this time/speed limit.

[earnies2]

Thanks I will get the solenoid and install it I might need some help.....thanks