58GreenMackB 15 Posted February 26, 2018 Share Posted February 26, 2018 I am looking into replacing a switch for the defroster circuit on a B series. I know the original switch was a 1 ohm 3 position switch, but need to see a circuit diagram to find a suitable replacement. Does anyone know where I can find one for the defroster circuit? Quote Link to post Share on other sites
j hancock 13,662 Posted February 26, 2018 Share Posted February 26, 2018 May want to check with the Mack Museum for a diagram. I looked at a couple of B wiring diagrams and neither listed the defroster circuit. Quote JimIt doesn't cost anything to pay attention. Link to post Share on other sites
58GreenMackB 15 Posted February 26, 2018 Author Share Posted February 26, 2018 What’s the best way to contact them to get this info? Quote Link to post Share on other sites
j hancock 13,662 Posted February 26, 2018 Share Posted February 26, 2018 Here is a link to their site. Could email them. https://www.macktruckshistoricalmuseum.org/ Quote JimIt doesn't cost anything to pay attention. Link to post Share on other sites
41chevy 10,259 Posted February 26, 2018 Share Posted February 26, 2018 My B61 the switch for the heater fan is the same switch for the defroster fan. Yours different? Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to post Share on other sites
58GreenMackB 15 Posted February 27, 2018 Author Share Posted February 27, 2018 (edited) A switch on the left side of my dash was replaced with a toggle switch, but I saw that some like mine had an extra hole with a knob I couldn't identify. I found out through researching various pictures of B series that there was a defroster switch in that hole. I will get the information from the Mack Museum to find out more about the switch. Not 100% sure it originally came on my truck. Even if it didn't, I will pass the knowledge onto others. It is my goal to return my truck with some minor upgrades to as close to original as possible. Always fun to learn something new. Edited February 27, 2018 by 58GreenMackB 1 Quote Link to post Share on other sites
Mike Stormo 7 Posted March 1, 2018 Share Posted March 1, 2018 following Quote Link to post Share on other sites
Freightrain 2,501 Posted March 26, 2018 Share Posted March 26, 2018 http://www.wattstruckcenter.com/store/index.php?route=product/product&path=59_71&product_id=378 Here is the switch and it has the resistor built in for the 2 speeds. No other wiring should be needed. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to post Share on other sites
Maddog13407 2,188 Posted March 26, 2018 Share Posted March 26, 2018 only the B series with the bigger heater with separate defroster fan had the switch and most i have seen were back wired right off the heater switch. i don't think there was a separate circuit for the defroster. Quote Link to post Share on other sites
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