PWM cooling fan(s) control using ECM

[andrewb70]

Originally Posted by GregWeld

Weather Pack connectors are good to 20 amps -- after that you switch to METRI-PAK 480 series connectors which will handle 42 amps. There are other "series" which will handle higher loads but 42 amps per fan is plenty of surplus as they'll pull about 30 amps or less.

Greg,

Excellent segway...I just picked up some 3 cavity Delphi GT480 connectors. They are rated at 42 amps, as you said.



I will run my power (+/-) and the PWM wires to the fan controller through this connector.

Andrew

[erick_e]

After finally experiencing the melted connector on my corvette, I decided to upgrade to a more reliable solution that won't derate with high under hood temperatures.

I ended up going with a Anderson Power connector rated at 75A.



If you are interested you can read my post at the link below.

http://www.corvetteforum.com/forums/...connector.html

[andrewb70]

I wonder why those factory connectors fail. Hard to imagine that it is simply current draw. The Corvette fan is said to be 400watts, so it should draw less than 35 amps. Heat? Moisture? Other causes of failure?

As I posted, I plan to use the Delphi GT480 series connector, which is rated at 42 amps. Where did you source the 3 cavity Anderson connectors and terminals?

Andrew

[erick_e]

Originally Posted by andrewb70

I wonder why those factory connectors fail. Hard to imagine that it is simply current draw. The Corvette fan is said to be 400watts, so it should draw less than 35 amps. Heat? Moisture? Other causes of failure?

As I posted, I plan to use the Delphi GT480 series connector, which is rated at 42 amps. Where did you source the 3 cavity Anderson connectors and terminals?

Andrew

In most, but not all, of the failures I've seen the fans have been set to run at 100% by a custom tune instead of the factory 90%.

Got my parts from Mouser. Detailed parts list is in my corvette forum thread. Total cost was less than $35 for the connectors and terminals.

[andrewb70]

Originally Posted by erick_e

In most, but not all, of the failures I've seen the fans have been set to run at 100% by a custom tune instead of the factory 90%.

Got my parts from Mouser. Detailed parts list is in my corvette forum thread. Total cost was less than $35 for the connectors and terminals.

I was under the impression that the fan controller won't even work with duty cycle numbers that are less than 5 and more than 90%. That was certainly the case when I was playing around with number on the Dominator ECU.

http://forums.holley.com/showthread....ling-Fan/page2

Andrew

[erick_e]

Originally Posted by andrewb70

I was under the impression that the fan controller won't even work with duty cycle numbers that are less than 5 and more than 90%. That was certainly the case when I was playing around with number on the Dominator ECU.

http://forums.holley.com/showthread....ling-Fan/page2

Andrew

This info is what SPAL technical support gave me for their brushless fans.

Originally Posted by andrewb70

Is there a % vs. VSS table? What's the thermostat temp on the Corvette?

Andrew

I haven't seen one either.

[erick_e]

I just got my 17" brushless fan and I am going to try to figure out how to have my factory ECM control it. Since these brushless fans are supposed to be factory on the 2014+ Corvette, I was able to compare the 2014 tune for brushless fan against the pre 2014 fans that have a separate PWM controller as seen in this thread.

In HPTuners the 2014 fan is listed as a PWM EV fan operating at 100Hz where the pre 2014 fans are PWM electric operating at 128Hz.

I'm thinking that I can just change the fan type and frequency in my tune and it should work.

Any thoughts?

[mikels]

Originally Posted by erick_e

In most, but not all, of the failures I've seen the fans have been set to run at 100% by a custom tune instead of the factory 90%.

Got my parts from Mouser. Detailed parts list is in my corvette forum thread. Total cost was less than $35 for the connectors and terminals.

Correct. Factory PWM controllers have max output @ 90% commanded duty cycle. I've never set them above to 'investigate potential failure modes', but could see that unknowledgeable calibrators could mistakenly assume 100%>90% so must be better.

Factory fans are rated in watts, stock C6 fan is a 400W (so @ 12.5 volts = 32 amps).

Newer 850W fans we've been using on higher output applications are ~68 amps (850/12.5). They use the connector that was shown a couple posts back. That and 10mm wire (between 6 and 8 ga). Have to consider generator output capability with all the high electrical loads.

Another benefit of PWM fans is they never have onrush of current draw since they ramp-up to output. Discrete fans can have considerable spike in amperage when turning on. (hard on electrical, idle stability, etc.)

Dave

[CarlC]

Originally Posted by mikels

Another benefit of PWM fans is they never have onrush of current draw since they ramp-up to output. Discrete fans can have considerable spike in amperage when turning on. (hard on electrical, idle stability, etc.)Dave

100% agree. Even with a 75A rating, the relay failed on the Camaro when using a Mark-VIII fan. The electrical connector at the fan also started to melt. PWM cured those problems. I won't ever do a discrete system again.

[130fe]

Just saw this on FB, here is another option for integrating the GM AC pressure switch. https://www.facebook.com/pages/BP-Au...53192731414826 BP Automotive sell a dryer that has a metric port built in.