Cold Blue Posted February 24, 2019 Report Share Posted February 24, 2019 I have the heater out of my 48 Plymouth to clean it up, flush all the rust out of the core, and replace the fan motor. The original motor is 6 volts - my car has been converted to 12 volts. I have a new 12 volt blower motor on the way. Please help me with the wiring! I am pitiful at electrical stuff... The original fan switch apparently operates thru a resistor (I think) which allows it to step down the voltage so that you can have 3 fan speeds. (I think...) Can I hook up the new 12 volt motor to the resistor thing just like my old motor, and will it work just fine? I don't want to fry it..I have attached pictures of the fan switch. One wire of the old fan motor connected to the small screw; the other fan wire connected to a ground. Thanks!!! Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 24, 2019 Report Share Posted February 24, 2019 You will burn the factory MoPar resister up using 12 volts. Oddly last thursday I picked up a 1951 Chevy using a new Chinese 12 volt fan motor (12 volt system) hooked up to the original 6 volt heater switch and resistor... it was cooked. Proper switch and resister required for 12 volt upgrade or change. Quote Link to comment Share on other sites More sharing options...
Cold Blue Posted February 24, 2019 Author Report Share Posted February 24, 2019 Thanks for the info Dodgeb4ya. I thought that might be the case... Quote Link to comment Share on other sites More sharing options...
greg g Posted February 24, 2019 Report Share Posted February 24, 2019 Also keep in mind the resistor puts out a lot of heat. The default is full speed. The resister lowers the voltage to vary the motor rpms so on high three is little if any resistance and thus less heat. Just keep it in mind you don't want any other wires flopping around near the switch. Quote Link to comment Share on other sites More sharing options...
chrysler1941 Posted February 24, 2019 Report Share Posted February 24, 2019 Bypass resistors and get a PWM regulator. It controls fan motor speed by square pulse. Regulate fan speed with multi turn knob. https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=6V-90V+15A+PWM+DC+Motor+Speed+Control+PWM+Controller+12V+24V+48V+64V+72V+1000W&_sacat=0 1 Quote Link to comment Share on other sites More sharing options...
Cold Blue Posted February 24, 2019 Author Report Share Posted February 24, 2019 Wow chrysler1941! That is one fancy set-up! Inexpensive too! Too cool. Would you have any idea how to keep the original heater knob? As you know, It is push/pull for the three fan speeds. The new one is rotary. Maybe I have to give up my old knob? Quote Link to comment Share on other sites More sharing options...
chrysler1941 Posted February 24, 2019 Report Share Posted February 24, 2019 2 hours ago, Cold Blue said: Wow chrysler1941! That is one fancy set-up! Inexpensive too! Too cool. Would you have any idea how to keep the original heater knob? As you know, It is push/pull for the three fan speeds. The new one is rotary. Maybe I have to give up my old knob? You have two options. One is mount rotating knob somewhere hidden, and use original switch as power to circuit. Pulling it all the way out will deliver full voltage. Second option. Your photo shows a two resistor type. Disconnect leads from rotating knob (potentiometer) and measure resistance. Divide value into two and get two ½ Watt resistors and swap them with the original resistors on switch. Connect the leads to each resistor. If you want other speeds, just change resistor value. Quote Link to comment Share on other sites More sharing options...
Cold Blue Posted February 25, 2019 Author Report Share Posted February 25, 2019 9 hours ago, chrysler1941 said: You have two options. One is mount rotating knob somewhere hidden, and use original switch as power to circuit. Pulling it all the way out will deliver full voltage. Second option. Your photo shows a two resistor type. Disconnect leads from rotating knob (potentiometer) and measure resistance. Divide value into two and get two ½ Watt resistors and swap them with the original resistors on switch. Connect the leads to each resistor. If you want other speeds, just change resistor value. I wish I had your electrical knowledge....Thanks Chrysler! Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted February 17, 2020 Report Share Posted February 17, 2020 I like this PMW solution. I think I will get a couple of Don Coatney's 12 volt blower motors...take my switch apart and jump all the lead to just create and on-off power switch and use the PMW with the pigtail switch to control the motor speed. That should then allow me to use a Power Stream Buck-Boost converters PST-DC/1260-11to run the 6 volt wipers. Everything else will be 12 volt so I have a complete solution. James. Quote Link to comment Share on other sites More sharing options...
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