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Heater rheostat shot

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Heater rheostat shot
#1
  This topic is about my 1960 Morris Minor 1000
pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
I removed the heater to access under dash repairs. While out I did a vacuum check using a brake vacuum bleeder I used doing the brakes. It worked well although I did lose some vacuum due to connecting the hose with electrical tape and sealing the other end with a plug and tape I figure. So I am pretty sure the core is OK. Next, the heater rheostat has a burnt coil. I took it apart to see the inside. Easy to do bending the tabs back exposing the interior. PO cut wires so I am not sure how to wire it back up. Two wires coming from the rheostat and that's all I got.
The heater is the next step in the interior repairs. Accept the firewall which will follow. The PO let the acid from the battery eat the back of the battery shelf out.
Can I replace the heater rheostat with a generic aftermarket? Smith type is 60$



Too soon old, too late smart, Dad always said.

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emjay Jim English
Etters, PA, USA   USA
I wouldn't expect anything fancy. Externally there are two wires, power in and ground. The rheostat should simply be in-line with one of them.

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Hey Jim, it's been awhile.
Thanks. The internal wiring has a washer wire connection to for both. No visible exit for the power of choice. (neg or pos ground)



Too soon old, too late smart, Dad always said.

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pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
This is one I found. Can I use it Jim?

PRODUCT SPECIFICATIONS:

Part No.: 7493-07
Description: Heavy Duty Rheostat Switch
Positions: Dim (Low) - Off - Bright (High)
Current Rating: Ceramic insulator with embedded coil
Terminals: 2 Screw
Resistance: 8.0 Ohms
Knob: Black Round/Bar
No actuator imprint
Mounting stem: 7/16"-28 thread, 15/32" (11.9mm) long
Case: Plated steel, 1.32" (33.52mm) dia. .88" (22.4mm) long
For 12V DC systems



Too soon old, too late smart, Dad always said.


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pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Getting closer to the wiring. White wire to hot and the switch is split at the to ground. Positive ground.
Now how about the switch choice?



Too soon old, too late smart, Dad always said.


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0123 Mike D
Biddulph, Staffs, UK   GBR
That rheostat is a pointless gimmick Paris.

The best you can say about it is that
the heat from it warms the cab a little.

Short it out, and fit an on of switch,

While the heater radiator is out, may I
suggest you give it a good flush please smiling smiley

Better still, get it flushed by a pro.



Edited 1 time(s). Last edit at 2018-12-15 10:35 AM by 0123.

emjay Jim English
Etters, PA, USA   USA
The direction of the current is not critical with a two wire motor since the fields and the armature both change so the motor direction stays the same. Your photo shows it all. Wire to the switch, then to the motor and then back to the outside world. On a side note when the alternators were being introduced the the need for negative earth, they used permanent magnet motors for a while with an extra wire to handle reversing polarity. However, that was with a squirrel cage fan where rotation difference still sends the air the same way but at different efficiencies. Your heaters has a simple blade fan so if the rotation is wrong, the air will go the wrong way.

As for the switch, the original was off, high, variable to low, but two speed would work just fine. That switch looks like the old one and the knob is close, but I have no idea if 8 ohms is the correct range. If you can measure the resistance of the motor and see how it runs with direct 12 volts, we can get a better idea of the results. For example, if the motor is 8 ohms, then with a 0-8ohm in line would reduce the voltage to 6 volts across the motor perhaps resulting in half speed. But the motor might not run with 6 volts. Applying different voltages to the motor and observing the results will also help confirm what resistance range is needed for the switch. Especially noting what 12 volts does because it may need some residual resistance, but I doubt it.

0123 Mike D
Biddulph, Staffs, UK   GBR
http://www.morrisminorspares.com/cooling-system-heater-c52/radiator-cooling-heating-c53/heater-switch-rheostat-type-for-round-heater-p829589

Best sit down b4 you read the price thumbs down



Edited 1 time(s). Last edit at 2018-12-15 10:55 AM by 0123.


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pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Hey Mike, I understand the "rheostat" is really not an appreciated value.
Emma will not be a restoration but rather a fun trainer car for a student or newbie. Possibly Shriner parade car but not anytime soon.
Unfogging the windscreen is primary and heat secondary. Although either is not going to be that critical with such a small compartment here in Georgia.
One thing about Jim English is: If you don't like the answer, don't ask the question. He is brilliant in my opinion.
However; I am going to use your suggestion and just turn the heater on and off.
An acid flush might open a hole? Fellow heater coil rebuilder near me says the coil is made of English veggie cans and thin.


In reply to # 33793 by 0123 That rheostat is a pointless gimmick Paris.

The best you can say about it is that
the heat from it warms the cab a little.

Short it out, and fit an on of switch,

While the heater radiator is out, may I
suggest you give it a good flush please yawning smiley)

Better still, get it flushed by a pro.



Too soon old, too late smart, Dad always said.

0123 Mike D
Biddulph, Staffs, UK   GBR
In reply to # 33804 by pvr Hey Mike, I understand the "rheostat" is really not an appreciated value.
Emma will not be a restoration but rather a fun trainer car for a student or newbie. Possibly Shriner parade car but not anytime soon.
Unfogging the windscreen is primary If you don't breath, that heater might just demist your screen.(

Open your quarter lights past centre
and heat secondary. Just as well smiling smiley
An 88C stat helps.
I used to remove the fan blade in winter.
And fit a second heater.
One for the screen.
And a bigger one for me.
Although either is not going to be that critical with such a small compartment here in Georgia.
One thing about Jim English is: If you don't like the answer, don't ask the question. He is brilliant in my opinion. thumbs up
However; I am going to use your suggestion and just turn the heater on and off.
An acid flush might open a hole? Then seal it dear Paris, Seal it. Fellow heater coil rebuilder near me says the coil is made of English veggie cans and thin. Cheekie Bugger

I daresay it's silted up too.


In reply to # 33793 by 0123 That rheostat is a pointless gimmick Paris.

The best you can say about it is that
the heat from it warms the cab a little.

Short it out, and fit an on of switch,

While the heater radiator is out, may I
suggest you give it a good flush please yawning smiley)

Better still, get it flushed by a pro.

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Thank you for your help.
There are two wires to the motor. One white and one black. The white goes to the back of the oil pressure switch and is keyed on and off. (Thks JQ)
The black wire goes to the rheostat or on/off switch then back out of the switch and connects to ground.
My rheostat was fried when I was testing my connections. I will try to repair by pulling the spring and reattaching it to the screw. If that doesn't work
I'll mount an on/off switch.
One more finished photo coming.



Too soon old, too late smart, Dad always said.


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0123 Mike D
Biddulph, Staffs, UK   GBR
Whilst it was normal to run stuff off the ignition switch Paris,
it bain't a good idea :-(

There's a risk that the load will cause
a significant voltage drop at the ignition coil.

Makes much more sense to use relays, fuses, and thick wires
to connect stuff you wish to stop running when you switch off.

pvr Avatar
pvr Paris VonRabenau
Reynolds, GA, USA   USA
1952 MG TD MkII
1960 Morris Minor 1000 "EMMA"
Where is factory then Mike please?



Too soon old, too late smart, Dad always said.

0123 Mike D
Biddulph, Staffs, UK   GBR
I'm afraid I do not understand your question Paris confused smiley

emjay Jim English
Etters, PA, USA   USA
The heaters were more most likely added at the dealer. The original wires connected to the green side of the fuse block and used the ground on the voltage regulator as I recall but different installers may have done it differently. These were two loose black wires that plugged into the pigtail from the heater. I'm not sure how they used the oil pressure circuit but it is fused (green versus white or yellow wire). I eliminate the separate wires through the bulkhead by connecting to the input to the fuel gauge (fused) and ground same as the turn signal indicator at the steering column.

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