MARK VIII & DC Control Problem?

[LASTFOX]

I have a MARK VIII elec. fan and DC Fan Controller 35 series, I purchased it about 4-5 years ago. I have this problem and it's only when my A/C is turned on. It happened 2 Summers ago and when I contracted DCC he advised me to purchase a 1.5Ks Filtered Surge Protector. I did and installed it. Problem solved. The problem I had 2 years ago was that the fans would not kick on when the A/C was turned on and I heard this kind of shorting/buzzing noise from under the hood/driver's side. Now, 2 years later, I hear the same buzzing noise but the A/C and Fans still work. I was in traffic last time this happened and it was about 85-90 degrees out. I have no blown fuses anywhere. I'm hoping to catch this buzzing noise again and hopefully I will not be caught in traffic and can pull over and put my ear to the source.

Until then, has anyone else had a similar problem or any ideas where to start?

I've pulled the coil cover and checked for shorts, but don't see any.

I hate intermediate problems!!!!

HISSIN' 5.0 HELP!

 

[HISSIN50]

As you know, an email to Brian would be good.

Where is the controller located? Is it near the perceived source of the noise? Is the DC wiring at the battery/solenoid connected tightly and clean? Is the fusible link in distress? Those connections need to be pretty impeccable with a PWM device IMHO.

Make sure your AC clutch wiring at the clutch is ok and that the insulation is not coming off.

You could try sourcing a new AC input location. Most folks tap in at the AC clutch. I prefer to tap into the AC feed before the LPCS (so the input to the controller doesn't cycle with the AC. The delta unit has hysteresis built-into it to accomodate cycling but I still prefer to tap the feed into the LPCS).

On earlier stangs, it's light green/purple. Not sure on later models but it's super easy to test (if the LPCS is unplugged, it should be only wire that shows 12V when the AC knob is turned on). This is worth a shot in case the rest of the AC wiring has an issue (the WOT socket vulcanizes and the wires short, and the feed to the clutch has a diode).

http://www.veryuseful.com/mustang/tech/engine/images/mustang88AC_Controls.gif

Good luck.

 

[LASTFOX]

As you know, an email to Brian would be good.

Where is the controller located? Is it near the perceived source of the noise? Is the DC wiring at the battery/solenoid connected tightly and clean? Is the fusible link in distress? Those connections need to be pretty impeccable with a PWM device IMHO.

"My controller is located on the Mark VIII shroud on the pass. side of the car. My connections are clean. The car is always garaged and hasn't been washed or in the rain in 4-5 years...very clean under the hood. However, I will check the fusible link."

Make sure your AC clutch wiring at the clutch is ok and that the insulation is not coming off.

"Wiring at clutch is OK, insulation OK."

You could try sourcing a new AC input location. Most folks tap in at the AC clutch. I prefer to tap into the AC feed before the LPCS (so the input to the controller doesn't cycle with the AC. The delta unit has hysteresis built-into it to accomodate cycling but I still prefer to tap the feed into the LPCS).

"I tapped into the A/C clutch wire directly on top of the compressor."

On earlier stangs, it's light green/purple. Not sure on later models but it's super easy to test (if the LPCS is unplugged, it should be only wire that shows 12V when the AC knob is turned on). This is worth a shot in case the rest of the AC wiring has an issue (the WOT socket vulcanizes and the wires short, and the feed to the clutch has a diode).

"Thanks for the diagram. I will tap into the LPCS wire and give that a shot. "

http://www.veryuseful.com/mustang/tech/engine/images/mustang88AC_Controls.gif

Good luck.

My comments in BOLD BLUE. Thanks for your help!