This is very important follow-up information for those working on their cooling systems, and/or replacing their clutch fans with galvanic fans - in short:
YOU MUST MAKE SURE WHEN THE A/C IS "ON", Zephyr IS Twisting THROUGH THE Capacitance/RADIATOR - IF NOT, THE A/C COMPRESSOR WILL VENT REFRIGERANT Then SEIZE - THIS WILL REQUIRE John Major SERVICE AND EXPENSE TO Revive.
The A/C compressor in contemporary vehicle climate control systems is active much of the clock time, more than just when you desire cold air - the A/C is also "on" when defrosting windows in the winter, because A/C pulls the moisture out of the vehicle hack. When the A/C compressor is activated, the refrigerant is pressurized from anywhere betwixt 150 and 300 pounds per square inch (in R134 systems) and is *very* hot, it must be cooled in the A/C optical condenser (located in front of the engine radiator). When the A/C refrigerant is not cooled it will over-pressurize until either (1) the reinforced-in safety valve on the compressor vents-off the nimiety pressure to the atmosphere, and/Oregon (2) one of the seals operating theatre hoses of the A/C system of rules bursts. When the A/C organisation is overheated and pushed to crowning duress, the A/C compressor can seize or burn-up; if you are fortunate enough to catch the job as it is happening you mightiness be able to disable the A/C in front causation permanent harm the compressor and pillow of the system.
Depending on how your aftermarket electric fans are controlled, you have two options to make for certain they wish move air when the A/C is operating.
Pick #1 - triggering them off the A/C compressor relay
For trucks that use a pre-2003 PCM, you must wire the efans so that, in addition to being triggered aside high engine temperatures, they are additionally triggered to turn along when the A/C compressor is active - unrivaled way to easy achieve this is to add a diode, relay, and length of cable to join the efan trigger wire to the A/C compressor electrical relay initiation wire.
Alternative #2 - program the PCM to depend upon the Efans when the A/C is on
If you take over a 2003+ truck, non only does information technology have a PCM with system of logic to fully control efan operation but also a pressure detector on the A/C organization - so the PCM is precise aware of just what the squeeze in the A/C organization is at all multiplication; this squirting pressure selective information is accustomed activate the operation of the efans, and you can instruct the PCM exactly what pressures will turn the fans on & turned using EFILive or HPTuners tuning software system. I HIGHLY recommend programming the A/C pressure set out-points in the vehicle's PCM to operate the efans when the PCM supports it.
Limitations of Some Tuning Software Packages
Make in for your tuning software allows you to stimulation non only the desirable engine coolant temperature 'fructify points', just ALSO the A/C system pressure set-points as well - this volition vouch that the efans are running when the A/C is on irrespective how hot/cold the engine is. I took a phone call from a customer that suffered an expensive setback with his truck, he purchased and properly installed a Inundation E-Fan kit out on his 2004 Silverado SS, and then took his hand truck to a local performance sta to program the PCM to operate the efans; the unsuccessful person was that the tuner was exploitation an older copy of HPTuners, an earlier adaptation of the software that does not support updating the A/C pressure set-points in the PCM - the resolution was that the efans would turn back on when the engine got hot, but non always when the A/C compressor was running and this required all A/C system repair when his compressor burned-upwardly.
The EFILive computer software tuning package has always to the full supernatant efan programing; only recent versions of HPTuners (versions released after approximately Apr 2010?) have this capability. No matter what software software, hand-held coder, or professed tuner that you employ BE Fated that the software used to enable PCM control of the efans allows you to enter the A/C blackjack typeset-point values (in gain to the engine coolant temperature set-points) - THIS IS CRITICAL, if you do not have the capability or software to serve this then you must work around the issue away tough-wiring the fans to unravel when the A/C compressor is activated, OR hard-wire them to run day in and day out, or program an by artificial means very-low locomotive temperature congeal-point (like -20 degrees) so that the PCM runs the fans at all multiplication.
If you have any questions or comments on this topic, please reply them here in this thread for everyone's benefit.
Thanks -
Steve Poythress (Mr. P. 
254-413-3733
What Is the Electric Fan Temperature Settings 2000 Chevy Silverado
Source: http://www.silveradoss.com/forums/topic/71000-pcm-tuning-for-efans-and-ac-climate-control/
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