1940 Heater/Defrost Control

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39SixSedanMan
Posts: 23
Joined: Tue Aug 25, 2009 7:14 am

1940 Heater/Defrost Control

Post by 39SixSedanMan » Tue Aug 25, 2009 7:25 am

I am attempting to help a friend restore his 1940 120 Heater/Defrost system. Unlike my 39, the sytem uses a single, reversing motor to drive either the defrost or heater and a single, multispeed switch. The switch seems to be a simple polarity reversing switch along with an onboard resistor for the low speeds. The motor itself has 4 leads coming from it, only two of which seem to show any resistance that may be the motor resistance or a short.

I will be checking the leads as they enter the motor to look for shorts/opens, but will still need to understand which lead is which and what to connect to the switch, power and ground. I haven't found any reference material on this in the 1940 literature, including the service letter literature. Perhaps its hidden in there and I just haven't found it yet.

Can anyone direct me to a resource for this?

Thanks,
Pat

dmdelavan
Posts: 187
Joined: Wed Jul 08, 2009 5:54 am

Re: 1940 Heater/Defrost Control

Post by dmdelavan » Tue Aug 25, 2009 7:47 am

Assuming we are dealing with the super deluxe heater (chrome handle switch) as you look at it from the back there are two coil spring resistors at the top. In between them is the yellow wire (A), brown is to the right (F) Red is to the left (F) also, and black is ground. On the standard switch a terminal on the left is labeled Mot (motor ?). I hope this is useful; if not, that's all the info I have. I will say on mine on resistor coil became so hot we had to cut it out and now only have low for defrost.
Don Gutting

39SixSedanMan
Posts: 23
Joined: Tue Aug 25, 2009 7:14 am

Re: 1940 Heater/Defrost Control

Post by 39SixSedanMan » Tue Aug 25, 2009 8:44 am

Don,
Thanks. Yes, this is the 5 position, chrome handled switch. Thank you for the information. Your reply tells me several things:
- This switch is missing one of the speed limiting resistors
- The leads from the motor must not be original as they have no color

I will check to see if there is a splice in the wiring, perhaps revealing the original wires and colors. Futher, how are power and ground from the car tied in? does the motor have a dedicated ground or does it rely on its chassis as a ground?

Thanks again for your help.
Pat

dmdelavan
Posts: 187
Joined: Wed Jul 08, 2009 5:54 am

Re: 1940 Heater/Defrost Control

Post by dmdelavan » Tue Aug 25, 2009 4:48 pm

We placed the ground at a safe and convenient location under the dash; can't be more specific than that. I believe the wiring diagram would show the power pick up. As for the wire colors I found all of mine were well faded, but looking for a splice as you mentioned, burrowing under the loom all the way to the motor or inspecting with a magnifying glass may reveal specs of color. Actually Ithink you only need to locate the red wire; if the other two or mixed up you will be using the heater side to defrost or v.v. and thenyou would simply switch them.
Don Gutting

39SixSedanMan
Posts: 23
Joined: Tue Aug 25, 2009 7:14 am

Re: 1940 Heater/Defrost Control

Post by 39SixSedanMan » Wed Aug 26, 2009 11:15 am

Don,
Thanks again for all your help, and I hope I am not being thick headed, but I am still confused with the quantity of wires coming out of the motor (4).

If the switch is a simple voltage reversing switch, I would expect the motor to only need 2 leads. However, it sounds that all four leads from the motor are to be connected to the switch (one yellow, one red, one brown, one ??).

Here is my assumption based on what you shared:
- the four wires from the motor tie directly to the switch
- the "A" connection of the switch is connected to the motor Yellow wire is connected to power
- the ground post of the switch is opposite the A post and is tied to one of the motor wires and to ground

Is this correct? If not, I do not know which post/wire to connect to ground and which to connect to power. I am trying to attach an image to this posting, but the site interface isn't too helpful.




THanks for your help,
Pat

dmdelavan
Posts: 187
Joined: Wed Jul 08, 2009 5:54 am

Re: 1940 Heater/Defrost Control

Post by dmdelavan » Wed Aug 26, 2009 5:32 pm

The shortest wire (Black) is the ground. Another (red probably) receives the power at the switch from the main ignition switch and terminates at the Field coil. The other two go to the armature. Reversing their attachment to the switch should reverse the motor which would only mean nothing more serious than that you may be using the wrong side of the switch.

Look carefully at the porcelain side of the switch; there should be evidence of color codes for red, brown and yellow.
Failing all this you might contact a good electrical shop. They can test the leads and tell you which goes where. That's how I got my information.
Don Gutting

39SixSedanMan
Posts: 23
Joined: Tue Aug 25, 2009 7:14 am

Re: 1940 Heater/Defrost Control

Post by 39SixSedanMan » Thu Aug 27, 2009 4:58 am

Don,
Thanks again for your help. I had considered the possibility that motor wiring brought the field and armature/commutator wires out separately. That was one of the possiblilities I considered and tested, but the fact that I saw no field resistance or armature resistance across the wires brings me to the conclusion that the wiring at or inside the motor has some issues. So, I will disassemble the motor and see what I can do.

Further, your statement that the field receives power separately (and seems to be always powered as long as the ignition is on) was something I DID NOT consider, so thank you for that.

I have put my electrical engineering background to use in the past having rebuilt many heater motors and a few Steward Warner wiper motors over the years and have been successful as long as I don't need to rewind the coil wires. It's a delicate job, but achievable. I may consider updating the speed resistors with some modern power resistors in order to provide the low speeds and to keep the resistors cool.

Dave Cirr showed me how to attach an image (Thanks Dave), so I hope it shows on this posting.

13Sept09: I deleted the image as I believe it was incorrect. The complete version is shown below.

Best Regards,
Pat
Last edited by 39SixSedanMan on Mon Sep 14, 2009 8:45 am, edited 2 times in total.

39SixSedanMan
Posts: 23
Joined: Tue Aug 25, 2009 7:14 am

Re: 1940 Heater/Defrost Control

Post by 39SixSedanMan » Thu Aug 27, 2009 12:22 pm

Don,
I think I have it now. Below is my revised electrical diagram based on your input. Let me know if it is correct. Thanks for your help.

Thanks Dave for helping me with the image upload and sorry for mispelling your name.

13Sept09: I deleted the image as I believe it was incorrect. The complete version is shown below.

Pat Mescher
Bellbrook, OH
Last edited by 39SixSedanMan on Mon Sep 14, 2009 8:46 am, edited 2 times in total.

dmdelavan
Posts: 187
Joined: Wed Jul 08, 2009 5:54 am

Re: 1940 Heater/Defrost Control

Post by dmdelavan » Thu Aug 27, 2009 6:11 pm

Pat,
I took another look at an extra heater and switch (my car is not here at this time) and the ground wire is longer,not shorter than the others and in fact extends well beyond the switch. Thus Ifeel it is grounded elsewhere. There is an unused terminal on the switch at the bottom and I'm assuming that is for the power lead.

Again, Yellow (armature) is between the two resistor coils. Red is to the left and brown is to the right. Both are labelled "field". I hope that is correct now and that Ihaven't screwed thingsup for you

jacko
Posts: 146
Joined: Sun Jul 19, 2009 12:55 pm

Re: 1940 Heater/Defrost Control

Post by jacko » Mon Aug 31, 2009 7:55 pm

I have a 1940 110, 1800 series and have completely restored the heater and motor. The most interesting thing I found was when I disassembled the motor, I found that the armature and the brushes still looked brand new. The reason was that the carbon brushes were not contacting the commutator since they were on a slightly skewed angle. I think the fan motor did not work from the very beginning. After realigning the brushes by using a file, the motor ran beautifully! Regarding the four wires, I simply laid out the switch and fan motor on the bench using a 6v battery charger as a power source and used trial and error to construct the wiring diagram. I installed a master toggle switch and 30 amp buss fuse upstream of the original porcelain switch. I did this because the old porcelain switch (from amperage measurements) appeared to have a small leak to ground and I did not want to take any chances. I now have a good working heater and only use the fan motor for short periods of time. I have found that the heater core and sheet metal shroud gives off a comfortable level of heat via radiation and free convection heat transfer without necessarily using the fan full time. When the fan runs, the motor draws about 20 amps. Seems like a lot but here is where I think the old switch has a leak to ground. I now enjoy driving the coupe in cold weather without getting blue lips.

Hope my experience helps,

Bob Jacko

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