Cool/Heat: climatizer 49 2r5

[robchhi]

Quick question, My 2r5 was converted to 12 volt and I think I need to reduce voltage to climatizer motor to 6volt. Is there a recommended
reducer and is there a amperage I need to have for the fan to run full speed?

[Skip Lackie]

I believe the 6v motor draws about 12 amps and has a 14 amp fuse in line. If I'm doing my E=IR correctly, you should put a 0.5 ohm resistor in the circuit and replace the fuse with a 7 amp. On the other hand, Delco made a 12v fan motor that is identical to the 6v unit in your truck. I think if you took your old motor to a good NAPA store they could order you a 12v motor for your truck. Make sure you tell them which way the motor turns.

[jcharlestc]

Don't worry about "providing amperage"; the motor will draw whatever it requires.

These motors work in a simple manner (compared to other types of DC motors), and one of the simplest type of speed controls to be recommended requires that you, somehow, determine the current being supplied to the motor now (i.e., being powered by 12-v) . This requires that you insert an ammeter in the supply line to the motor. Be very aware that most multimeters--in order to avoid "burning out" their very small internal components-- have a very stringent time-requirement (a "cool-off" time) when measuring high(er) currents; one of mine, on the 10-amp range, states, "5 seconds ON, 1 minute OFF". Another states "30 seconds ON, 15 minutes OFF" (!!)

In the meantime (depending on how well built, or not, the motor is), you can probably get away with doing a version of what the multimeters want: run it for a while; turn it off for a while. You might even get away with running it full time, and taking advantage of the double speed of the blower. Note, though, that I am not recommending this.

[jcharlestc]

Skip Lackie posted his comment while I was still typing mine--I can't comment on the electrical portions, but this part, "...On the other hand, Delco made a 12v fan motor that is identical to the 6v unit in your truck. I think if you took your old motor to a good NAPA store they could order you a 12v motor for your truck. Make sure you tell them which way the motor turns."
are two of the best ways to handle the problem.
Would still be interested if you could get a 'amps' reading off your motor, for possible suggestions...

[robchhi]

A bit Greek for me but I can read-up and give this a go. Thanks!

[gordr]

This is something you could easily do by trial and error. 12 volts will not hurt a 6 volt fan motor. It will run faster, but probably not double speed. Electric motors generate "back EMF" that opposes the supplied power, so they tend to self-regulate. Now, the resistor in the switch is sized for 6 volt use, and probably won't cause my much of a drop at all in speed if the motor is fed on 12 volts. Just go to a junkyard and get the resistor network out of some more modern car with 12 volt fans. Some are even easy to get at! Experiment with various combinations of the resistors in the network, or add a second one, even, until you get "fast" and "slow" speeds to your liking. The resistors will get very hot, so mount them in the air stream from the fan.

[StudeRich]

What does a "Resister Network" look like Gord?
Would we be looking for a Printed Circuit on a piece of Micarta insulator in the Junk Cars?

[gordr]

Here is a resistor network:

https://tinyurl.com/45mtu56x

[robchhi]

I believe I have original switch control so the "resistor in the switch" is the concern?

[robchhi]

So the current switch may burn out w/12v connection?

[jackb]

I bought a NAPA motor for my 2R6. You will have 2 choices in prices. I bought the cheapie......started making noise in a month or so....

[gordr]

Rob, likely the switch won't burn out, but the resistor in it will be largely ineffective at controlling fan speed.

[robchhi]

Great! !!
When it was on a 12 v w/reducer it ran very slow (little noisy) w/little air movement so I just thought that’s the way it was in 1949. Then the reducer died and thus my question. I’m in Colorado so I was disappointed in that it gets pretty cold here.
So yesterday, I hooked it up to a 12v line and boy did it run. Great air flow but ran it for a brief second or 2 as not to mess up the switch. I’ll give it a good trial run today. Thanks!!