Blower Switch affects Tach.
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Junior User
Joined: Jun 2003
Posts: 83
Likes: 0
From: Rome, Italy
Blower Switch affects Tach.
I have an 84' F250 2WD that I am slowly but surely restoring. I have rewired the truck completely but now have got it down to 2 gremlins. Whenever I turn on the heater and then switch the fan speed it causes my Tachometer to "peg-out" It has to be a short, right? I have replaced the switch and the motor and put another (used) resistor in with the same results. The truck did not originally have a Tachometer, I added it in on one of my Junk-Yard forays and it works well. I changed the wiring harness and the wire sheet on the back of the instrument cluster to match the Tachs original vehicle, but have ot changed out any computers. Could this be the problem? I havebeen told the resistor is a likely culprit, and since the one I currntly have was from a junked F150 I can't be sure it was good. The Blower blows on all setings, and in accordance with the setting ie.. H/M/L, it just shorts out my Tach when its on. I also noticed the other day that when I connect up my AC compressor it stays on despite the switch. I know it is bad hat is why I disconnect it, but would this be a reason as well?
Post Fiend
Joined: Feb 2000
Posts: 11,496
Likes: 6
From: Kansas
Having a bad component (a relay for example) can wreck all kinds of havoc. You might do better at Franklins forum that deals with electronics.
https://www.ford-trucks.com/forums/f...?s=&forumid=62
https://www.ford-trucks.com/forums/f...?s=&forumid=62
