VCCA Home Forums TECHNICAL - GENERAL Radios, Tools, Accessories 1938 heater & electrical questions

Hi All,

I just bought a used 1938 Deluxe heater unit for my coupe, which did not originally have one, and I'm looking for some assistance with some questions that I have about it. My first question is about the location of the switches. It has the defroster motor on top, so it came with two switches, but I don't know where the switches mount. There's nothing in the owner's manual that mentions the heater and/or shows where they go on the dash, and I haven't been able to find any pictures. The next question is about the wiring. How does the wiring run, and where do the switches get their power from? I don't know if the switches I got with this unit are originals, so if anyone has pictures of the correct switches and/or their locations, or of the instructions that came with the heater accessory, that would be a big help. I see that there is also supposed to be a hot water shutoff valve on the engine, so I'm looking for that part. Finally, the car was converted to 12 volts sometime ago, and because none of the gauges read correctly, I'm contemplating returning it to the 6-volt system. Most of the wiring looks original, though there have been some modifications and splices done, so I'm also considering getting a replacement harness. Does anyone know of a good source for one?

Thanks,
Steve Leunig

Lots for good questions.

First of all, unless the motors for the heater and defroster have been converted to 12 volts, you will need to do that or add voltage reducers so they do not burn out. Converting back to 6 volts might have some advantages for you.

Your comment about instruments not reading accurately is a little surprising. The only instrument in your car that is voltage sensitive is the fuel gauge. The ammeter reads current and is not affected by voltage. The oil pressure and temperature gauges are mechanically driven.

I am sure that over the years there have been many variations of switch location and wiring. If Gene sees this post he might be able to provide the installation instructions that came with the unit. It was a dealer installed accessory.

I think you are wise to evaluate the overall condition of the wiring harness. I had to replace the original one in my '37 Master coupe. The lacquer coated cloth insulation was so brittle that it would break off if you moved the wire. It was obvious that this was a fire waiting to happen.

Many people on this forum have had good experiences with both YNZ and Rhode Island wiring for accurate and well made replacement harnesses. There is a lead time for both because they make the harness after you order it.

Hi Rusty,

Thanks for your reply. This is my first pre-war car, so there's a lot for me to learn about it. When I said the gauges weren't reading correctly, I should have said that I was referring to the gas gauge and ammeter. I will take a look at the two wiring vendors that you mentioned. In terms of changing it back to 6 volts, I presume I'll need to swap out all the bulbs along with the voltage regulator. Not sure if the generator was modified when they changed it over. The literature I've seen says that the heater switch lights up, so there's another question. Thanks!

Steve Leunig
#21510

The heater and defroster switch mounts under the bottom lip of the dash to the right of the steering wheel. Thre are two large holes already there. The knobs point down. If correct for a 1938 the lighted knobs will be a light gray color. 1939 used the same knobs but were tan.
The power wires are attached to the side of the ignaitin switch that is hot oly when the key is in the on position. Inline fuses shoud be used,
Please send me an email so I can send you pictures and info....chevgene@msn.com..............I used the address in you have in your profile but did not work.

Steve,

Both Rusty and Gene have given you excellent information.

Although neither would (I suspect) suggest the following, I do. If you can find a Wirey Joe wiring harness in good condition, I would use it instead of the more expensive YNZ or Rhode Island. Those would be fresher of course but more expensive. The WJ would be fine for a driver and were well made with the appropriate tracers for identification. You almost can't get the harness in wrong. Note to scheptics: Only if the harness is in the friable state is there any excess reason to fear a short out and/or fire. So lets don't go there. I've already said "in good condition." Everything should be fuse protected.

I would strongly suggest that you change back to 6-volt. All things being of equally good condition, that is all you need. The original 6-Volt syatem gets blames for all most as many things as Ethanol does.

The brass/bronze fitting thta attaches at the water pump may be had by advertising in the "Wanted" setion in the Chatt. It's a fairly common item.

Ol' Rusty fudged a bit on the oil pressure and the tempertature gages being mechanically driver. He will likely adjust his reply on that. No big deal.

I don't know when the toggle switches came out but if Gene says they weren't right ones for 38, but he would know.

Good luck with your project,

Charlie

the toggle or lever type swich was new for 1940.

OK,

Thanks Gene. Another thing I didn't know but do now.

I realize I don't know what they looked like before1940. You know, in ancient time when "Sweetie' was still young.' Agrin:

Best,

Charlie

Thanks for the comment about "mechanical" gauges. That is a term frequently used for gauges that read information without converting the signal to an electrical input. (Google it Charlie) On our older cars the oil pressure and temperature are read directly without any electrical signal.

The oil pressure reading is due to physical oil pressure making a coil "unwind" in the gauge. the coil is at the end of the long line connected to the block. The needle is attached to that coil.

The temperature gauge needle moves when the coil turns due to expansion of the fluid trapped in the bulb and connecting line. The fluid expands when it is heated by the coolant circulating in the engine.

I am not sure why your ammeter is not reading. It could have been damaged if the amperage output of the 12 volt generator was much higher than the gauge could handle. If my information is correct that gauge is set up to show +/- 30 amps. The original generator was designed to produce a maximum of 28 amps. A 50 amp generator might have been more than the gauge could handle.

With respect to the conversion back to 6 volts, I expect you will need to replace the generator. When the car was converted to 12 volts it was either replaced by a 12 volt generator or there were a few shops that could rewind the armature and change the fields to make the original generator produce 12 volts.

I have examples of BOTH heater knobs the 38/39 correct factory issue if you get that far
let me know

When the change to 12 volts is done with an alternator, it is common practice to bypass the ammeter. Maybe that has been done here.