BLOWER MOTOR AMPERE DRAW

[live4theking]

I've been in the dash of my 68 plenty. I'm thinking you could sit the relays on top of the HVAC box behind the glove box. Or maybe mount them to the left (driver) side of the box. The harness you would need to make would be considerable shorter than. One of the ends of the box where the flanges go together on my 68 had an extra hole you could use as the mount.

 

[Justin Plant]

Go to Advance Auto parts or one of the other big three. They sell horn relay and button and wiring kits on the sales floor. Look for the horn section. There are diagrams on the back, simple rugged and inexpensive four prong relays. I've used several in the past, The electric fuel pump in my El Camino is wired through one of these kits. Check it out, it's really simple.

 

[Gerald Morris]

I'm a little surprised at the amount of draw at start-up. The running draw seems about right... and makes a really good argument for doing some sort of relay.

Start up currents ARE high, esp on old school motors. This is what "Slo-blo" fuses were for, or fusible links for that matter. Even today, many of the cheapo chinese electric radiator fan kits use absurdly over size breakers with the fan, to allow for startup current spikes. It ALWAYS takes more work to overcome a static state rather than maintain a steady one!

 

[fury fan]

It's been a month, so don't know if this is completed yet.

I fully support the use of relays. I wouldn't worry too much about where to mount them - if you make the harness long enough you can mount them anywhere.
Behind the passenger-side kickpanel? Fastened to a small plate that is fastened to the bottom lip of the dashboard (so that 1 screw removes all 3 relays)?
The mounting should be such that you can dismount and pull the harness/relays out for diagnosing, or such that you can get a testlight on them (which sounds not likely).


OR:
A few years ago the blower resistor failed in my '99 Buick. When I got the replacement part, I was immediately smitten for retrofitting somethign like it into an older car.
I haven't had the need to pursue it, though.

Resistor module roughly $30, resistor pigtail is roughly $12. Relay can be any standard Bosch-type relay wired in.
I don't see the red-black wire's connector as available at RA, but it could be cut off and standard spade male/female disconnects used instead.

Would require requisite electrical skills, but I'd assume that is OK based on the discussion here.


I think this works via + and - connecting at the red and black (into the module) and the 7-terminal connector inputs 5 speed triggers from the switch, and outputs a ground and the reduced voltage for the motor. But would need verified.

Obviously there may be better solutions out there, and/or I could be totally wrong about how this wiring works.

One thing I see - this resistor has sealant on it, for mounting it in the heater box. Presumably, then, it is standard practice for any resistors used for the blower motor to be in airflow to keep them cool.
Whether an adapter place can be easily made for this particular module would remain to be seen.

And if you could find a 4-5 position toggle switch, you could have more speeds!


1999 BUICK CENTURY 3.1L V6 Blower Motor Connector | RockAuto

1999 BUICK CENTURY 3.1L V6 Blower Motor Control Module / Resistor | RockAuto

 

[Gerald Morris]

It's been a month, so don't know if this is completed yet.

I fully support the use of relays. I wouldn't worry too much about where to mount them - if you make the harness long enough you can mount them anywhere.
Behind the passenger-side kickpanel? Fastened to a small plate that is fastened to the bottom lip of the dashboard (so that 1 screw removes all 3 relays)?
The mounting should be such that you can dismount and pull the harness/relays out for diagnosing, or such that you can get a testlight on them (which sounds not likely).


OR:
A few years ago the blower resistor failed in my '99 Buick. When I got the replacement part, I was immediately smitten for retrofitting somethign like it into an older car.
I haven't had the need to pursue it, though.

Resistor module roughly $30, resistor pigtail is roughly $12. Relay can be any standard Bosch-type relay wired in.
I don't see the red-black wire's connector as available at RA, but it could be cut off and standard spade male/female disconnects used instead.

Would require requisite electrical skills, but I'd assume that is OK based on the discussion here.


I think this works via + and - connecting at the red and black (into the module) and the 7-terminal connector inputs 5 speed triggers from the switch, and outputs a ground and the reduced voltage for the motor. But would need verified.

Obviously there may be better solutions out there, and/or I could be totally wrong about how this wiring works.

One thing I see - this resistor has sealant on it, for mounting it in the heater box. Presumably, then, it is standard practice for any resistors used for the blower motor to be in airflow to keep them cool.
Whether an adapter place can be easily made for this particular module would remain to be seen.

And if you could find a 4-5 position toggle switch, you could have more speeds!


1999 BUICK CENTURY 3.1L V6 Blower Motor Connector | RockAuto

View attachment 622633

1999 BUICK CENTURY 3.1L V6 Blower Motor Control Module / Resistor | RockAuto
View attachment 622634

If you want to get really clever w this:

Get a ROTARY toggle switch! https://www.jameco.com/z/G3SR022-R-...-Before-Break-Solder-Lug_101574.html?CID=GOOG

I think 2P 6T should suffice for most non-digital minded folk. Now, you will need a bank of several resistors with the power capacity appropriate to the maximum current your blower motor would draw. If that comes to 15A, then, 12V * 15A = 180W. 3 should suffice, as you can then combine them in the following ways:
1. none -> max speed
2. 3 in parallel, min resistance, 2nd highest speed
3. 2 in parallel
4. 1 in series w motor
5. 2 in series w motor
6. 3 in series w motor VERY LOW SPEED

You need to decide how much relay switching you will want with such a monstrous primitive system also. OR,

Get a BIG 200W potentiometer. Probably easier and less expensive.

3 speeds is usually plenty choice, and now you understand why most folks stop with that.

Best of luck!

 

[Ross Wooldridge]

Correct - and if I wanted to use a relay I'd have to create a harness and install a relay for each fan speed (using the switch's wires going to the original resistor setup).

 

[Sixpactogo]

Your amp test pretty much tells the tale. Your motor is in good shape. A 30 amp fuse will handle that 38 amp spike. Is the 13 amp draw on high speed or low? IMO, You have a bad connection somewhere. Probably at the switch. Those push on spade connectors leave something to be desired. Chrysler engineers knew what they were doing when they designed these circuits but they didn't plan on them lasting for 50 years. If you can get to the connections on the switch and resistor, I would clean them good and make sure they have a tight connection. Adding three relays seems like a burden and overkill to me. We all know what opinions are good for but that is mine. Good luck getting it figured out Ross.

 

[Ross Wooldridge]

The draw tests were on the bench and in the car, and were identical. I agree, the connectors and old wiring are the issue. New AC vacuum control switch, NOS 3 speed fan switch and new wiring are coming as a winter project.

The most enjoyable process of gutting the dash awaits me.

Yay...

 

[Ripinator]

The draw tests were on the bench and in the car, and were identical. I agree, the connectors and old wiring are the issue. New AC vacuum control switch, NOS 3 speed fan switch and new wiring are coming as a winter project.

The most enjoyable process of gutting the dash awaits me.

Yay...

Aaarrrgghh! My Standard FCBO offer still stands. . .

 

[pgadler]

Correct - and if I wanted to use a relay I'd have to create a harness and install a relay for each fan speed (using the switch's wires going to the original resistor setup).

Sry, havn't been under the dash. Is the resistor block separate from the switch, under the dash, or integrated to the switch?

 

[Ross Wooldridge]

Separate. Not too hard to get to.

@Ripinator - remind me of your offer please... old brain, poor memory

 

[Ripinator]

Separate. Not too hard to get to.

@Ripinator - remind me of your offer please... old brain, poor memory

Standard C-Body offer = $2500. . .

 

[Ross Wooldridge]