VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 38 MD sedan heater control

38 MD sdn....whats the original heater control look like ?? someone has installed a rotating lighted knob under side of dash with one control..took out heater and got both motors working but switch only has one control ? so something is missing here ? are these available ? ..sc

It's probably a rheostat switch. Were both motors connected to the same switch? Normally there would be a separate switch for the defroster. All of the switches I've seen hang under the dash as you describe but I've read here that the OEM setup is for them to stick down through the lip under the dash with only the knob showing.

correct Tiny!
only 1 knob showing,
have the untouched heater set in 2 38/39 cars i have with a switch and knob that took me a couple years to find just extra knobs!

What got me to ask question ..look under ebay search 38 chevrolet heater control #201434478932 $59 bucks..so if my rheostat has only one wire then I will need two ?one for heat and one for defrost ?

The 1938 heater off and on switch mounts under the lip of the instrument panel. It has a lighted knob and controls the speed of the motor. If the car also has the accessory defroster it will have an identicle switch for the defroster motor.

And through the years people pretty much used what was handy so most ended up with various switches hanging under the dash rather than specifically using the correct switch. Most people, myself included, would have a difficult time telling a "correct" switch from an "incorrect" switch. My knowledge has evolved some because of the knowledgeable folks here on chat but I have a long way to go to catch up. Truth be told most don't care if a switch is absolutely correct or not unless it's something glaringly obvious like a residential wall switch stuck on the dash.

Would not be surprised to see that. I once bought a car that was wired with household wire and a thermostat from a wall unit controlled an electric fan behind the radiator.

Guys,

See below a couple pictures of the dash of my 38 Master Coupe; I think the heater and defroster switches are the originals that Gene describes. They have multiple speeds and light up when turned on. They attach on the bottom edge of the dash in pre-drilled holes.

Jim

Thats great info ..what a nice car you have compared to mine, now I will be sick driving mine.ha ha PS I made an extra connection while I had dash out to fuse on amp meter so next time I wont need jaws of life to get to it,just remove ash tray.. my rig has an aftermarket light switch thats too wide so they unhooked the vent handle under dash screws..I see no easy fix other than getting the correct switch..I have 4 model A's some for sale //I like a tad newer cars that have a heater and roll cage built in..had a good 35 std sdn,great car but small like a VW..sc

The pictured heater switch is the type of the original BUT the original has stricght sides of the larger diameter (like bottom of switch shown) and in 1938 they were a light gray color. Chevrolet used that switch for a number of years but the knob color was changed to match the general color of the dash knobs, etc. in a Master Deluxe series. The Master had the brown knobs.

Note the pedal pads for 1938 had horizontal ribs with a Bow Tie in thee center. 1940 was the first to have verticle groves.

my 38 MD with 51k miles had a lighter color knob, my 39 MD with 71k miles , had the same color knob, BUT the 2 n.o.s. knobs i bought, were of the brownish color you talk about

The 1938 and 1939 knobs were the same shape but a different color. The 1939 knob was more of a tan color. Same for the heater. The heaters were the same but the knobs on the doors were of different colors. There is no saying that the dealer could have 1938 heaters left over and installed them in 1939's or the owner did not get a heater installed in his 1938 until1939 and coors didn't always match,
The 1938 heater switch was discontinued in 1942 and replaced by the 1939 switch so things can be all mixed-up.

Chevgene,
your a wealth of information!
when i bought the "brown" knobs i had no idea on the 2 colors offered,,,,,,, will post pics of these knobs later so everyone can see the difference

Great, thank You. And the 1937 was a darker brown, the 1936 a medium gray and 1935 redish brown.
There are some aftermarket switches that looked kind of like the '39 switch, probably made by th smae company. I have some laying around here some place.

The other earlier years ,,,,
do they have the same shape knob and profile as these 2?

now i need to find the 35 style with redish knob and switch

Wow what a beautiful car! If the heater control is the knob on the right, what is the one under the dash on the left?

The one on the left is the proper location for the heater switch and the defroster switch. The proper holes are already there for the installation.

Knob on left under dash is defrost fan one in middle is heater fan..mine was correct after all..had correct knobs in jockey box.sc

Gene,

Could you clarify for me your last entry? Did both the Master and Master Deluxe in 1938 have the gray knob with straight sides that you describe? Mine is a Master, so should it technically have the light gray knobs in 1938? If so, these brown ones with the ribbed bottoms must have been added after 1938--they were in the car when I found it.

I'll need to switch out those pedal pads to horizontal ones!

Thanks,

Jim

The control knobs (choke the throttle) on your 1938 Master are correct for your car, The Master Deluxe had the light gray knobs.
For the heater and defroster switches only the light gray heater switch knobs came with the heater.

To further clearify the 1935-1937 heater switch knobs looked like the knobs (the shape) that you have on your 1938.

Thanks for the clarification, Gene!

thank you,,,,,,,,,
now i know what to look for


WANTED, 1935 MASTER DELUXE PARTS

Is this the switch with the flat side to which Chevy Gene is referring?

Hope this works, it is the first time I have tried to upload a picture. It is on photobucket and this is the link.
[img:left]http://s350.photobucket.com/user/booshmaster1/media/IMG_3851_zpsn7p3iavn.jpg.html?filters[user]=145867816&filters[recent]=1&sort=1&o=1[/img]

I will upload a couple more pix if this works.

Brad