Secondary fan help
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Junior Member
Joined: Jan 2000
Posts: 44
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From: Mississauga, Ontario, Canada
Secondary fan help
I have a 1988 iroc z28 with dual fans
Here is what I understand.
My primary fan (driver's side) turns on when
1) Engine temp rises to 230 degrees or
2) A/C is engaged and vehicle speed is over ~35 mph or
3) The ALDL diagnostic terminal is grounded.
I think it is controlled by a coolant switch on the drivers side of the engine block but i am not sure.
I think the secondary fan (passenger side) turns on when
1) Engine temp rises to ~243 degrees AND
2) A/C is engaged and vehicle speed is over ~35 mph.
The secondary fan turns on if the pressure on the A/C liquid line is above 232 psig (150 F for R-12). There is a pressure switch on the liquid line. The ECM monitors the status of the secondary cooling fan. The secondary fan should run on a very hot day with the A/C on.
I think the second fan is controlled by a coolant temp switch between number 6 and 8 spark plugs.
Now here is what i have done.
I installed a high compression motor which generates heat. I also removed all the air conditioning plumbing from the firewall forward including the evap unit that looks like a rad to increase airflow through the engine radiator. I still have all the wiring.
What i want is to have my secondary fan come on automatically (shortly after the primary fan) when the engine reaches x degrees. I will control the threshold of the second fan via an aftermarket coolant temp switch or the ecm or both.
In other words i think i want to fool the ecm into thinking the air conditioning is always on and control the secondary fan soley through tempature.
How do i do this. I am not really interested in manual switches. Any ideas?
David
Here is what I understand.
My primary fan (driver's side) turns on when
1) Engine temp rises to 230 degrees or
2) A/C is engaged and vehicle speed is over ~35 mph or
3) The ALDL diagnostic terminal is grounded.
I think it is controlled by a coolant switch on the drivers side of the engine block but i am not sure.
I think the secondary fan (passenger side) turns on when
1) Engine temp rises to ~243 degrees AND
2) A/C is engaged and vehicle speed is over ~35 mph.
The secondary fan turns on if the pressure on the A/C liquid line is above 232 psig (150 F for R-12). There is a pressure switch on the liquid line. The ECM monitors the status of the secondary cooling fan. The secondary fan should run on a very hot day with the A/C on.
I think the second fan is controlled by a coolant temp switch between number 6 and 8 spark plugs.
Now here is what i have done.
I installed a high compression motor which generates heat. I also removed all the air conditioning plumbing from the firewall forward including the evap unit that looks like a rad to increase airflow through the engine radiator. I still have all the wiring.
What i want is to have my secondary fan come on automatically (shortly after the primary fan) when the engine reaches x degrees. I will control the threshold of the second fan via an aftermarket coolant temp switch or the ecm or both.
In other words i think i want to fool the ecm into thinking the air conditioning is always on and control the secondary fan soley through tempature.
How do i do this. I am not really interested in manual switches. Any ideas?
David
Member
Joined: Oct 2000
Posts: 405
Likes: 0
From: Gulf Coast
Car: 1988 Trans Am GTA
Engine: 5.0 TPI
Transmission: TH700-R4
Axle/Gears: 3.27
IMO, let the ECM control the driver side fan and install an adjustable switch to control the passenger side. I would use a Hayden adjustable switch which has the probe that goes in between the fins on the radiator. That way you can adjust it to any temperature you want.
You can also use the fan switch on the block to control the pasenger side fan and use an adjustable to control the driver side if you think the cut-in temperature set by the ECM is too high.
There is also a tech. articles on this subject.
Good luck.
You can also use the fan switch on the block to control the pasenger side fan and use an adjustable to control the driver side if you think the cut-in temperature set by the ECM is too high.
There is also a tech. articles on this subject.
Good luck.
Thread Starter
Junior Member
Joined: Jan 2000
Posts: 44
Likes: 0
From: Mississauga, Ontario, Canada
<font face="Verdana, Arial" size="2">Originally posted by Ozzy88GTA:
IMO, let the ECM control the driver side fan and install an adjustable switch to control the passenger side. I would use a Hayden adjustable switch which has the probe that goes in between the fins on the radiator. That way you can adjust it to any temperature you want.
You can also use the fan switch on the block to control the pasenger side fan and use an adjustable to control the driver side if you think the cut-in temperature set by the ECM is too high.
There is also a tech. articles on this subject.
Good luck.</font>
IMO, let the ECM control the driver side fan and install an adjustable switch to control the passenger side. I would use a Hayden adjustable switch which has the probe that goes in between the fins on the radiator. That way you can adjust it to any temperature you want.
You can also use the fan switch on the block to control the pasenger side fan and use an adjustable to control the driver side if you think the cut-in temperature set by the ECM is too high.
There is also a tech. articles on this subject.
Good luck.</font>
Thanks - i will work on it!
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