What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?

I don't know what words to use to search for specifically this on
ebay/amazon/google. Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. If
I had a car make and model and year, I could find one that way. Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. ;-(

Thanks.

On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?

I don't know what words to use to search for specifically this on
ebay/amazon/google. Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. If
I had a car make and model and year, I could find one that way. Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

--
Vic

On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

On Wed, 22 Aug 2012 16:29:07 -0400, Reed wrote:

On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?

I don't know what words to use to search for specifically this on
ebay/amazon/google. Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. If
I had a car make and model and year, I could find one that way. Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

Wow. This is just about perfect. Thanks.

The end of the tube is a lot bigger than the tube itself. Would you
put it in the heater hose, the radiator hose, or mount it on the
radiator?


**And JCW too. I went through the wholle paper catalog which is still
pretty big (not the one they send you when you request one, but the
one they include when you buy something) , but didn't look online.

micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

BTW, the thermostat I forgot to remove from an earlier car had a
rubber thing with a slope on each side and a groove in the middle to
hold the tube, so the tube wouldn't be crushed by the hose clamp.

I was goingto do something like that if I put the tube in a radiator
hose.

----------

Wow. This is just about perfect. Thanks.

The end of the tube is a lot bigger than the tube itself. Would you
put it in the heater hose, the radiator hose, or mount it on the
radiator?


**And JCW too. I went through the wholle paper catalog which is still
pretty big (not the one they send you when you request one, but the
one they include when you buy something) , but didn't look online.


On Wed, 22 Aug 2012 16:29:07 -0400, Reed wrote:

On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?

I don't know what words to use to search for specifically this on
ebay/amazon/google. Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. If
I had a car make and model and year, I could find one that way. Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

BTW, the thermostat I forgot to remove from an earlier car had a
rubber thing with a slope on each side and a groove in the middle to
hold the tube, so the tube wouldn't be crushed by the hose clamp.

I was goingto do something like that if I put the tube in a radiator
hose.

----------

Wow. This is just about perfect. Thanks.

The end of the tube is a lot bigger than the tube itself. Would you
put it in the heater hose, the radiator hose, or mount it on the
radiator?


**And JCW too. I went through the wholle paper catalog which is still
pretty big (not the one they send you when you request one, but the
one they include when you buy something) , but didn't look online.


On Wed, 22 Aug 2012 16:29:07 -0400, Reed wrote:

On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?

I don't know what words to use to search for specifically this on
ebay/amazon/google. Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. If
I had a car make and model and year, I could find one that way. Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

On Wed, 22 Aug 2012 21:28:32 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

micky wrote:
On Wed, 22 Aug 2012 21:28:32 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

Hi,
Then there is 'stat controlling the rad fan. You need separate one?
How about using one already there.

On Aug 22, 11:34*pm, micky wrote:
BTW, the thermostat I forgot to remove from an earlier car had a
rubber thing with a slope on each side and a groove in the middle to
hold the tube, so the tube wouldn't be crushed by the hose clamp.

I was goingto do something like that if I put the tube in a radiator
hose.

* *----------

Wow. *This is just about perfect. *Thanks.

The end of the tube is a lot bigger than the tube itself. *Would *you
put it in the heater hose, the radiator hose, or mount it on the
radiator?

**And JCW too. *I went through the wholle paper catalog which is still
pretty big (not the one they send you when you request one, but the
one they include when you buy something) , but didn't look online.



On Wed, 22 Aug 2012 16:29:07 -0400, Reed wrote:
On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. * Am I being clear?

I don't know what words to use *to search for specifically this on
ebay/amazon/google. *Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. *If
I had a car make and model and year, I could find one that way. * Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. * ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool.../p2000903....- Hide quoted text -

- Show quoted text -

You would think being that it's 2012, all cars would
have this by now, but they don't.
My 1980 Mercedes has it so that you don't get
cold air blowing. It also has a small seperate
electric pump for the heater core to get hot water
there as fast as possible.

snip

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

Wow. This is just about perfect. Thanks.

The end of the tube is a lot bigger than the tube itself. Would you
put it in the heater hose, the radiator hose, or mount it on the
radiator?


Instructions at
http://www.haydenauto.com/Online%20C...g/Content.aspx
says to mount it on the backside of rad fins using provided mounting
hardware

On Thu, 23 Aug 2012 07:39:01 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 21:28:32 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

Hi,
Then there is 'stat controlling the rad fan. You need separate one?
How about using one already there.

Probably. I don't want to wait until the water is hot enough to turn
on the radiator fan. It's warm enough to heat the passenger
compartment quite a bit before then.

Plus the 12v might come from different places., and not just from the
battery, for the two fans. I'll look into that.

On Thu, 23 Aug 2012 07:18:22 -0700 (PDT), "
wrote:

On Aug 22, 11:34*pm, micky wrote:
BTW, the thermostat I forgot to remove from an earlier car had a
rubber thing with a slope on each side and a groove in the middle to
hold the tube, so the tube wouldn't be crushed by the hose clamp.

I was goingto do something like that if I put the tube in a radiator
hose.

* *----------

Wow. *This is just about perfect. *Thanks.

The end of the tube is a lot bigger than the tube itself. *Would *you
put it in the heater hose, the radiator hose, or mount it on the
radiator?

**And JCW too. *I went through the wholle paper catalog which is still
pretty big (not the one they send you when you request one, but the
one they include when you buy something) , but didn't look online.



On Wed, 22 Aug 2012 16:29:07 -0400, Reed wrote:
On 8/22/12 3:26 PM, micky wrote:
What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. * Am I being clear?

I don't know what words to use *to search for specifically this on
ebay/amazon/google. *Do you know what words capture the "tube" part,
and in order to look at non-car parts, the turn-on/close-switch when
hot part?

Nor do I know what kind of car used/uses this kind of thermostat. *If
I had a car make and model and year, I could find one that way. * Do
you know a car that used such a thermostat.

Originally, I bought one from JCWhitney based on the picture in the
catalog, but I sold the car and forgot to remove the thermostat. * ;-(

Thanks.

You mean one like this ??

http://www.jcwhitney.com/engine-cool.../p2000903....- Hide quoted text -

- Show quoted text -

You would think being that it's 2012, all cars would
have this by now, but they don't.
My 1980 Mercedes has it so that you don't get
cold air blowing. It also has a small seperate
electric pump for the heater core to get hot water
there as fast as possible.

Last I checked some new cars don't even have buzzers to tell you when
you've stopped the engine but not turned off the headlights, even
though other cars had that 20+ years ago, and K-Mart sold such a
buzzer for $1.50. That's important because without it, you come back
to a dead battery. I'm not counting the ones that allow the lights
to stay on for a while on purpose.

And t here is something my 2000 Toryota does't have that my '84 and
later Chryslers did. For one thing, the driver's door won't open
unless it's unlocked. But I think there was something electrical too.

On Thu, 23 Aug 2012 11:34:11 -0400, Reed wrote:

snip

You mean one like this ??

http://www.jcwhitney.com/engine-cool...wx?filterid=j1

Wow. This is just about perfect. Thanks.

The end of the tube is a lot bigger than the tube itself. Would you
put it in the heater hose, the radiator hose, or mount it on the
radiator?


Instructions at
http://www.haydenauto.com/Online%20C...g/Content.aspx
says to mount it on the backside of rad fins using provided mounting
hardware

Wow. Thanks. I love it when there are online instructions.

On Sat, 25 Aug 2012 11:34:09 -0400, micky
wrote:

On Thu, 23 Aug 2012 07:39:01 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 21:28:32 -0600, Tony Hwang
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400, micky
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

Hi,
Then there is 'stat controlling the rad fan. You need separate one?
How about using one already there.

Probably.

I mean: Proably I need a separate one.

I don't want to wait until the water is hot enough to turn
on the radiator fan. It's warm enough to heat the passenger
compartment quite a bit before then.

Plus the 12v might come from different places., and not just from the
battery, for the two fans. I'll look into that.

I've looked at the wiring diagrams 3 or 4 times, but never before for
this purpose.

So I looked again and the radiator fan is powered through the engine
main relay and the fan no.1 relay, and then goes to ground. Its
thermostat connects to the fan no. 3 relay and is in the midst of a
jumble of wires

The heater fan gets power directly from the through the heater relay
(one side of which IS connected to the battery) but tts ground wire
doesn't go straight to ground. It goes to the "AC blower motor
linear controller", and the diagram doesnt' show what's in that.

So I don't know how to use the same thermostat, and I'd be afraid to
try. I suspect it can't be done.

On 8/26/12 3:32 PM, micky wrote:
On Sat, 25 Aug 2012 11:34:09 -0400,
wrote:

On Thu, 23 Aug 2012 07:39:01 -0600, Tony
wrote:



micky wrote:
On Wed, 22 Aug 2012 21:28:32 -0600, Tony
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400,
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

Hi,
Then there is 'stat controlling the rad fan. You need separate one?
How about using one already there.

Probably.

I mean: Proably I need a separate one.

I don't want to wait until the water is hot enough to turn
on the radiator fan. It's warm enough to heat the passenger
compartment quite a bit before then.

Plus the 12v might come from different places., and not just from the
battery, for the two fans. I'll look into that.

I've looked at the wiring diagrams 3 or 4 times, but never before for
this purpose.

So I looked again and the radiator fan is powered through the engine
main relay and the fan no.1 relay, and then goes to ground. Its
thermostat connects to the fan no. 3 relay and is in the midst of a
jumble of wires

The heater fan gets power directly from the through the heater relay
(one side of which IS connected to the battery) but tts ground wire
doesn't go straight to ground. It goes to the "AC blower motor
linear controller", and the diagram doesnt' show what's in that.

So I don't know how to use the same thermostat, and I'd be afraid to
try. I suspect it can't be done.

You need to wire the new switch in series somewhere between the
Battery and the "Controller". It will act like another "Heater relay"

Now, as you describe =

Batt----Fan------------------HtrRelay----Controller---Ground

After=

Batt----Fan----NewSwitch-----HtrRelay----Controller---Ground

New switch could also go between Batt and Fan if easier to wire; or
between HtrRelay and Controller

This way both the NewSw and HtrRelay must be closed for fan to run

On Sun, 26 Aug 2012 16:41:46 -0400, Reed wrote:

On 8/26/12 3:32 PM, micky wrote:
On Sat, 25 Aug 2012 11:34:09 -0400,
wrote:

On Thu, 23 Aug 2012 07:39:01 -0600, Tony
wrote:



micky wrote:
On Wed, 22 Aug 2012 21:28:32 -0600, Tony
wrote:



micky wrote:
On Wed, 22 Aug 2012 15:29:45 -0500, Vic Smith
wrote:

On Wed, 22 Aug 2012 15:26:41 -0400,
wrote:

What do you call this, where do you find it?

I need to buy the kind of thermostat used to turn on a car's radiator
fan (or at least an electric swtich that will close at 120^ F or
higher) , and I also need it to use as a sensor a thin tube (2-4 mm)
that will go into a radiator or heater hose, between the metal housing
and the hose that surrounds it. Am I being clear?


No. Just explain the purpose of the switch and where you want to use
it. Then you'll probably get answers.

In the winter, I don't want the heater fan to go on when the engine is
cold because cold air will come out of the heater**. So I want to put
the sensor in the heater hose and let it turn the fan on when the
coolant is reasonably warm.

**OTOH, if I turn the fan off with the switch on the heater/AC
control, I'll go days without turning the fan on again, until I
finally notice how cold I am.

Hi,
Did not mention how old the car is. Does it have belt driven fan or DC
motor driven one?

2000 Toyota. DC motor for the radiator fan, but the fan I'm trying
to stop is the heater fan. (also a DC motor.)

Hi,
Then there is 'stat controlling the rad fan. You need separate one?
How about using one already there.

Probably.

I mean: Proably I need a separate one.

I don't want to wait until the water is hot enough to turn
on the radiator fan. It's warm enough to heat the passenger
compartment quite a bit before then.

Plus the 12v might come from different places., and not just from the
battery, for the two fans. I'll look into that.

I've looked at the wiring diagrams 3 or 4 times, but never before for
this purpose.

So I looked again and the radiator fan is powered through the engine
main relay and the fan no.1 relay, and then goes to ground. Its
thermostat connects to the fan no. 3 relay and is in the midst of a
jumble of wires

The heater fan gets power directly from the through the heater relay
(one side of which IS connected to the battery) but tts ground wire
doesn't go straight to ground. It goes to the "AC blower motor
linear controller", and the diagram doesnt' show what's in that.

So I don't know how to use the same thermostat, and I'd be afraid to
try. I suspect it can't be done.

You need to wire the new switch in series somewhere between the
Battery and the "Controller". It will act like another "Heater relay"

Now, as you describe =

Batt----Fan------------------HtrRelay----Controller---Ground

After=

Batt----Fan----NewSwitch-----HtrRelay----Controller---Ground

New switch could also go between Batt and Fan if easier to wire; or
between HtrRelay and Controller

This way both the NewSw and HtrRelay must be closed for fan to run

Thanks. Will do.