Dodge RamCharger Central banner
1 - 12 of 12 Posts

Super Moderator
'79 Macho 360 Magnum, Comp 480 cam, Hughes springs, 650 Thunder AVS, Pertronix Flamethrower ignition
Joined
7,244 Posts
Discussion Starter · #1 ·
The high speed fan quit working in my '79 heater. I replaced the fan switch with a NOS switch a few years ago. Could it be the fan itself or a diode? Thoughts?
 

Administrator
Joined
62,315 Posts

Administrator
Joined
62,315 Posts
DODGEBOYS said:
the blower motor resister could be bad also
The high speed bypasses the resistor. ;)
 

Super Moderator
'79 Macho 360 Magnum, Comp 480 cam, Hughes springs, 650 Thunder AVS, Pertronix Flamethrower ignition
Joined
7,244 Posts
Discussion Starter · #5 ·
The fan now blows at the same speed in either position. Is that resistor behind the glove box on some type of tiny circuit board thing on the outside of the heater box? (I forget exactly what it looks like of the top of my head) i remember something looking burnt around there. Ill take another look tomorrow at that thing i saw back behind there.
 

Registered
Joined
24 Posts
Is putting a relay on the high-speed circuit of the blower fan generally a good idea for any of these old Dodges?聽 When I got my '72 D200 the ignition switch was fried and the wires at the connector slightly melted, I've read about a mod to remove the larger wires and put them in a beefier separate connector which I plan to do.聽 But after getting a new switch in there I found out the blower motor still doesn't turn on at all; I'm guessing those old blower motors draw a lot of current?聽 Hence putting in a relay to take that load off the main wiring harness in the cab?
 

Administrator
Joined
62,315 Posts
MopaRnD said:
Is putting a relay on the high-speed circuit of the blower fan generally a good idea for any of these old Dodges?
Yes, it take the 10 to 15 amp load off the switch, when in high speed.

When I got my '72 D200 the ignition switch was fried and the wires at the connector slightly melted, I've read about a mod to remove the larger wires and put them in a beefier separate connector which I plan to do. But after getting a new switch in there I found out the blower motor still doesn't turn on at all; I'm guessing those old blower motors draw a lot of current? Hence putting in a relay to take that load off the main wiring harness in the cab?
Yes, I believe it was a modification Dodge did in the 70's. Like you say, there is lots of current going through the multi terminal connector. Pulling the main wires out of the connector and using bigger connector was supposed to solve the issue, but I have still seen those melted also. If you are running amps, radios, and other add on items, I would go with a relay.

In the later 90's, Dodge ran into the almost the same issue again, then the fix was to use a relay to take the load off the switch terminals. You could say it was a similar issue with horns, the early 70, Dodge ran all the current through the steering wheel. The aftermarket industry even jumped in, and made a kit to convert the horns circuit with relays. And of course, in the late 70's Dodge made the horn relay standard.

I am a believer in using relays to take high current loads off switch contacts, whenever possible. Cheaper to replace a worn out relay, then a heater switch.

Canadian country boy said:
The fan now blows at the same speed in either position. Is that resistor behind the glove box on some type of tiny circuit board thing on the outside of the heater box? (I forget exactly what it looks like of the top of my head) i remember something looking burnt around there. Ill take another look tomorrow at that thing i saw back behind there.
Could be, but my money is on the switch. IIRC, you can find the resistor block by pulling the dash box out, and looking in to the top front of the heater box.
 

Registered
Joined
5,094 Posts
may want to look into getting a solid state relay for the blower motor. you can just wire it in at the blower motor and it should work on all speeds instead of just 1 like most other relay mods. cheapest solid state relays i know of are for the 96-00 caravan, voyagers and town an county radiator fan relay. getting them at auto recyclers may be the cheapest way even tho they can be a bit tricky to get at since they are on the driver side frame rail.
 

Administrator
Joined
62,315 Posts
crazzywolfie said:
may want to look into getting a solid state relay for the blower motor. you can just wire it in at the blower motor and it should work on all speeds instead of just 1 like most other relay mods. cheapest solid state relays i know of are for the 96-00 caravan, voyagers and town an county radiator fan relay. getting them at auto recyclers may be the cheapest way even tho they can be a bit tricky to get at since they are on the driver side frame rail.
The power has to go through the resistor block, to vary the speeds. No sort of relay can change that, unless it is a DC motor speed controller you are referring to. That would get a bit complicated to wire.
 

Registered
Joined
5,094 Posts
a solid state relay has no moving parts in it. should work just fine with the resistor block or at least the one i installed in my 93 did. it pretty much puts out the same amount of power as it receives. it would likely be why the caravans sounded like they had multi speed fans when they only had single speed fans.
 

Registered
Joined
13,500 Posts
makes sense聽 聽 power - resistor - relay - fan聽 ......... transistor so low volts still pull it "in"聽 as opposed to a coil type that would need 12v to firmly "make" the contacts ...聽 BUT that won't make a slow on high fan run faster , the HIGH speed by passes the resistor deal , so if its slow on high look for burned connector's ( resistance) OR a motor going bad OR shit dragging on fan blades ( too much leaf load ?)聽 check connections all the way back TO the fuse pannel including the heater controll ...
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top