2000 Chevy Silverado Electric Fan a/c Pressure Enable
This is very important followup information for those working on their cooling systems, and/or replacing their hold fans with electric fans - in short:
YOU MUST MAKE SURE WHEN THE A/C IS "ON", AIR IS MOVING THROUGH THE Capacitor/RADIATOR - IF NOT, THE A/C COMPRESSOR WILL VENT REFRIGERANT AND And so SEIZE - THIS WILL REQUIRE MAJOR Service of process AND Disbursement TO REPAIR.
The A/C compressor in contemporaneous fomite climate control systems is active much of the time, more than just when you desire cold aerate - the A/C is also "on" when defrosting windows in the winter, because A/C pulls the wet prohibited of the vehicle cab. When the A/C compressor is activated, the cold is pressurised from anywhere between 150 and 300 psi (in R134 systems) and is *real* illegal, it must be cooled in the A/C condenser (set in front of the engine radiator). When the A/C refrigerating is not cooled it will over-pressurize until either (1) the built-in safety valve on the compressor vents-off the overindulgence pres to the atmosphere, and/or (2) one of the seals operating theatre hoses of the A/C system bursts. When the A/C system is overheated and pushed to ultimate duress, the A/C compressor can assume or tan-up; if you are fortunate enough to catch the job as it is happening you might be able to incapacitate the A/C before causing permanent legal injury the compressor and rest of the system.
Depending on how your aftermarket electric fans are controlled, you have two options to make a point they will 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, to boot to being triggered by high engine temperatures, they are additionally triggered to turn on when the A/C compressor is active - one way to easily achieve this is to ADD a diode, relay, and length of wire to join the efan trigger wire to the A/C compressor relay initiation telegram.
Option #2 - program the PCM to hinge upon the Efans when the A/C is on
If you have a 2003+ truck, not only does IT have a PCM with logic to fully control efan operation but also a pressure sensor on the A/C system - so the PCM is very aware of exactly what the press in the A/C system is at all multiplication; this moving press information is used to trip the operation of the efans, and you can apprise the PCM exactly what pressures leave turn the fans connected & inactive using EFILive or HPTuners tuning software program. I Extremely recommend programing the A/C pressure set-points in the vehicle's PCM to operate the efans when the PCM supports it.
Limitations of Many Tuning Computer software Packages
Make destined your tuning software allows you to input not merely the desired engine coolant temperature 'set points', but ALSO the A/C scheme coerce set-points as well - this will guarantee that the efans are running when the A/C is on no thing how hot/inhumane the engine is. I took a phone address from a client that suffered an expensive setback with his truck, he purchased and right installed a Torrent E-Fan kit on his 2004 Silverado SS, and then took his truck to a localised performance shop to program the PCM to operate the efans; the failure was that the radio was using an older copy of HPTuners, an originally version of the software package that does non support updating the A/C pressure level position-points in the PCM - the answer was that the efans would turn on when the locomotive got calefactive, merely not always when the A/C compressor was running and this obligatory complete A/C system furbish up when his compressor burned-up.
The EFILive software tuning package has always fully supernatant efan programming; lone recent versions of HPTuners (versions free afterwards approximately April 2010?) have this capability. No matter what software, hand-held programmer, or professional tuner that you employ BE Trustworthy that the software used to enable PCM ensure of the efans allows you to enter the A/C pressure set-point values (in addition to the engine coolant temperature set-points) - THIS IS CRITICAL, if you do not give birth the capacity or software to exercise this so you must work around the make out by hard-wiring the fans to run when the A/C compressor is combat-ready, or hard-wire them to run day in and day out, or program an artificially very-low engine temperature set-point (like -20 degrees) so that the PCM runs the fans at all times.
If you have any questions or comments happening this topic, delight reply them hither in this string for everyone's benefit.
Thanks -
Steve Poythress (Mr. P. 
254-413-3733
2000 Chevy Silverado Electric Fan a/c Pressure Enable
Source: http://www.silveradoss.com/forums/topic/71000-pcm-tuning-for-efans-and-ac-climate-control/
