HVAC is a weak area of mine (and transmissions) and I need some help!

I was under the impressions that when the A/C is in operation that the fan should be running continuously to draw air across the condenser for best performance. Currently my A/C cycling pressure switch is cycling every couple of minutes. The fan will run for 1-2 minutes, secure, then start again about 15 seconds later. I've never paid attention until now, but it seems to be a stressful evolution to me, but I don't know if that's what it's supposed to do or not. Is this normal or do I need to investigate this as an abnormality? If anybody can let me know what my fan should really be doing please let me know. Thanks.

By the way I have a '97 SCab XLT 4x2 5.4L with towing package (CA model).

 

unless you have installed electric fans your truck is equipped with a mechanical fan and clutch. The clutch is temp. sensitive and as the air through the radiator get hot it causes the clutch to engage and move more air. Commonly the roar you hear sometimes is the fan turning at full speed. The A/C cycling only effects the mechanical fan by increasing the hot air moving through the radiator and condensor mounted in front of the rad. Once the air cools off the clutch lets off and the fan slows down. I have installed electric fans and one of them is dedicated to run anytime the a/c compressor is on. This seems to have improved my a/c a bit.

 

Pestco1,

I have installed the dual 16" electric fans from Troyer Performance. I tapped into the a/c cycling pressure switch and my fan is cycling often (1 1/2 to 2 min) which is a 30A starting surge. My a/c blows arctic cold but it can't be good for the fan or the electrical system. I'm trying to find a wire to connect to for the trigger of that fan for whenever I select a/c. Where did you hook up to on yours?

 

I just finished installing FAL e-fans in my 02 King Ranch Screw and found that what I THOUGHT was the A/C compressor Negative Signal is actually making my engine impossible to start.

My question revolves around the actual identity of the A/C compressor negative connection (or controller wires) so that the e-fans engage only in conjunction with the A/C compressor.

Does this sound right to you guys? BTW my "negative" connection to the A/C compressor is actually from the blue wire of the blue and gray pair of wires that enters the A/C compressor from the bottom driver's side..Using a multimeter and connecting the black (negative) to the blue A/C wire and the red (pos) of the multimeter to the battery it read the circuit as complete and positive voltage of 12.56V, same as the battery poles. This led me to believe that the blue wire was a negative and would then connect into the negative "A/C ON" portion of the e-fan controller. Any help is appreciated much. Thanks

 

I have the troyer electric fans. When the AC is on the fan connected to the AC will run contineously. Which wire did you splice into?
I used the Red/Yellow wire between the AC pressure cutoff and the AC clutch cycling pressure switch. The fan comes on as soon as I engage the ac and only turns off with the ac. It runs all the time.

Fritz

 

On the AC systems I have worked on, the pressure switch interrupts the 12 supply to the compressor clutch,,, so if you tie your fan relay to the compressor side of the switch , your fan will cycle with the compressor.. If you tie to the other side of the switch your fan will stay on as long as you have AC selected with the controls inside.

 

I tapped into the main power dist. on the drivers side as per the instructions( been a while so I could not tell you the exact wire colors ) Fan runs as long as a/c is selected. I liked this kit mainly because of the dual controllers allows for fans to run independent of each other. Just didn't like the way they mount to the Rad. core. Been installed for 8 months and no problems, very effecent even in high temps. and stopped in traffic.