Your mechanic probably knows this but ...

The radiator fan is three speed controlled by voltages provided to is
through a BIG resistor pack on the frame just under the radiator. These
can go bad but usually do not.

Fan speeds one a two have separate relays in the main relay box under
the hood just in front of the drivers side windshield. Fan speed three
has a BIG double wide relay in the AUX relay panel under the dash by the
driver's left knee.

Speed one is operated when the AC is turned on and if it is a turbo it
runs during after-run cooling.

Speed two typically turns on and off if you are driving in traffic.

You would only hear speed three when the temperature is very hot. It
comes on when the temperature gage is about ten degrees to the right of
the center mark.

Any of the relays can cause the fan to run and take the battery down.

Two other components of the system to be aware of are a fusible link for
the fan ground just below the brake master cylinder. The other component
is the thermo switch that operates speeds two and three. It is located
just below the lower radiator hose on the back of the radiator.

Say Hello to Steve Sears.

Tony

Stephen Clark wrote:
> Got a good charge on the battery, reinstalled it. Battery voltage is now
> 12.63 installed in the car.
>
> Car starts! Charging voltage is 13.88 at the jumper terminal. Let it run for
> 30 minutes, turned off, restarted ok. Car is up to normal op temp, shut
> down, waited about 5 minutes, then radiator fan came on for 30-40 seconds.
> Then 5 minutes later, fan comes on again, but only for a split-second, then
> turns off. Hmmmm...
>
> I suspect that there is a drain on the battery that is related to the
> radiator fan temp sensor or relays. This could account for the battery going
> down. I'll have my mechanic check it out next week, as I don't have the
> troubleshooting procedures for the fan controls.
>
> So, Dave, you win! ( subject to verification by my mechanic next week! )
> Thanks!
>
> And thanks to all for your insights..you guys are great!
>

 

Your mechanic probably knows this but ...

The radiator fan is three speed controlled by voltages provided to is
through a BIG resistor pack on the frame just under the radiator. These
can go bad but usually do not.

Fan speeds one a two have separate relays in the main relay box under
the hood just in front of the drivers side windshield. Fan speed three
has a BIG double wide relay in the AUX relay panel under the dash by the
driver's left knee.

Speed one is operated when the AC is turned on and if it is a turbo it
runs during after-run cooling.

Speed two typically turns on and off if you are driving in traffic.

You would only hear speed three when the temperature is very hot. It
comes on when the temperature gage is about ten degrees to the right of
the center mark.

Any of the relays can cause the fan to run and take the battery down.

Two other components of the system to be aware of are a fusible link for
the fan ground just below the brake master cylinder. The other component
is the thermo switch that operates speeds two and three. It is located
just below the lower radiator hose on the back of the radiator.

Say Hello to Steve Sears.

Tony

Stephen Clark wrote:
> Got a good charge on the battery, reinstalled it. Battery voltage is now
> 12.63 installed in the car.
>
> Car starts! Charging voltage is 13.88 at the jumper terminal. Let it run for
> 30 minutes, turned off, restarted ok. Car is up to normal op temp, shut
> down, waited about 5 minutes, then radiator fan came on for 30-40 seconds.
> Then 5 minutes later, fan comes on again, but only for a split-second, then
> turns off. Hmmmm...
>
> I suspect that there is a drain on the battery that is related to the
> radiator fan temp sensor or relays. This could account for the battery going
> down. I'll have my mechanic check it out next week, as I don't have the
> troubleshooting procedures for the fan controls.
>
> So, Dave, you win! ( subject to verification by my mechanic next week! )
> Thanks!
>
> And thanks to all for your insights..you guys are great!
>

 

Your mechanic probably knows this but ...

The radiator fan is three speed controlled by voltages provided to is
through a BIG resistor pack on the frame just under the radiator. These
can go bad but usually do not.

Fan speeds one a two have separate relays in the main relay box under
the hood just in front of the drivers side windshield. Fan speed three
has a BIG double wide relay in the AUX relay panel under the dash by the
driver's left knee.

Speed one is operated when the AC is turned on and if it is a turbo it
runs during after-run cooling.

Speed two typically turns on and off if you are driving in traffic.

You would only hear speed three when the temperature is very hot. It
comes on when the temperature gage is about ten degrees to the right of
the center mark.

Any of the relays can cause the fan to run and take the battery down.

Two other components of the system to be aware of are a fusible link for
the fan ground just below the brake master cylinder. The other component
is the thermo switch that operates speeds two and three. It is located
just below the lower radiator hose on the back of the radiator.

Say Hello to Steve Sears.

Tony

Stephen Clark wrote:
> Got a good charge on the battery, reinstalled it. Battery voltage is now
> 12.63 installed in the car.
>
> Car starts! Charging voltage is 13.88 at the jumper terminal. Let it run for
> 30 minutes, turned off, restarted ok. Car is up to normal op temp, shut
> down, waited about 5 minutes, then radiator fan came on for 30-40 seconds.
> Then 5 minutes later, fan comes on again, but only for a split-second, then
> turns off. Hmmmm...
>
> I suspect that there is a drain on the battery that is related to the
> radiator fan temp sensor or relays. This could account for the battery going
> down. I'll have my mechanic check it out next week, as I don't have the
> troubleshooting procedures for the fan controls.
>
> So, Dave, you win! ( subject to verification by my mechanic next week! )
> Thanks!
>
> And thanks to all for your insights..you guys are great!
>

 

Thanks, Tony, I was vaguely aware of how the fan controls work. The only
thing I have noticed that is abnormal, other than the fan coming on very
briefly when the car is off after a hot run, is that fan speed two has not
worked with the a/c off for quite some time. For example, if I am in stop
and go traffic in the winter, and the engine gets hot enough, fan speed
three will come on ( sounds like an aircraft taking off! ) until the
coolant temp drops below it's preset threshold. The engine never overheats,
so this has not been a problem from a practical point of view, so I have not
done anything about it.

However I usually have the a/c on about eight months out of the year,
because it's hot and muggy in Houston even in the spring and fall. Fan speed
one is sufficient to keep the coolant temp normal with the a/c on, and I'm
not sure that fan speed two ever comes on when the a/c is kept on all the
time.

I'm thinking maybe I should check/replace the relay for fan speed two? If
the temp sensor were the culprit, why would fan speed three operate at all?
Am I on the right track?

I'll send Steve Sears your greeting!

Have a great Memorial Day weekend...


--
Stephen Clark
89 Audi 100
Houston, Texas USA

 

Thanks, Tony, I was vaguely aware of how the fan controls work. The only
thing I have noticed that is abnormal, other than the fan coming on very
briefly when the car is off after a hot run, is that fan speed two has not
worked with the a/c off for quite some time. For example, if I am in stop
and go traffic in the winter, and the engine gets hot enough, fan speed
three will come on ( sounds like an aircraft taking off! ) until the
coolant temp drops below it's preset threshold. The engine never overheats,
so this has not been a problem from a practical point of view, so I have not
done anything about it.

However I usually have the a/c on about eight months out of the year,
because it's hot and muggy in Houston even in the spring and fall. Fan speed
one is sufficient to keep the coolant temp normal with the a/c on, and I'm
not sure that fan speed two ever comes on when the a/c is kept on all the
time.

I'm thinking maybe I should check/replace the relay for fan speed two? If
the temp sensor were the culprit, why would fan speed three operate at all?
Am I on the right track?

I'll send Steve Sears your greeting!

Have a great Memorial Day weekend...


--
Stephen Clark
89 Audi 100
Houston, Texas USA

 

Thanks, Tony, I was vaguely aware of how the fan controls work. The only
thing I have noticed that is abnormal, other than the fan coming on very
briefly when the car is off after a hot run, is that fan speed two has not
worked with the a/c off for quite some time. For example, if I am in stop
and go traffic in the winter, and the engine gets hot enough, fan speed
three will come on ( sounds like an aircraft taking off! ) until the
coolant temp drops below it's preset threshold. The engine never overheats,
so this has not been a problem from a practical point of view, so I have not
done anything about it.

However I usually have the a/c on about eight months out of the year,
because it's hot and muggy in Houston even in the spring and fall. Fan speed
one is sufficient to keep the coolant temp normal with the a/c on, and I'm
not sure that fan speed two ever comes on when the a/c is kept on all the
time.

I'm thinking maybe I should check/replace the relay for fan speed two? If
the temp sensor were the culprit, why would fan speed three operate at all?
Am I on the right track?

I'll send Steve Sears your greeting!

Have a great Memorial Day weekend...


--
Stephen Clark
89 Audi 100
Houston, Texas USA

 

Thanks, Tony, I was vaguely aware of how the fan controls work. The only
thing I have noticed that is abnormal, other than the fan coming on very
briefly when the car is off after a hot run, is that fan speed two has not
worked with the a/c off for quite some time. For example, if I am in stop
and go traffic in the winter, and the engine gets hot enough, fan speed
three will come on ( sounds like an aircraft taking off! ) until the
coolant temp drops below it's preset threshold. The engine never overheats,
so this has not been a problem from a practical point of view, so I have not
done anything about it.

However I usually have the a/c on about eight months out of the year,
because it's hot and muggy in Houston even in the spring and fall. Fan speed
one is sufficient to keep the coolant temp normal with the a/c on, and I'm
not sure that fan speed two ever comes on when the a/c is kept on all the
time.

I'm thinking maybe I should check/replace the relay for fan speed two? If
the temp sensor were the culprit, why would fan speed three operate at all?
Am I on the right track?

I'll send Steve Sears your greeting!

Have a great Memorial Day weekend...


--
Stephen Clark
89 Audi 100
Houston, Texas USA

 

Stephen Clark wrote:
> Thanks, Tony, I was vaguely aware of how the fan controls work. The only
> thing I have noticed that is abnormal, other than the fan coming on very
> briefly when the car is off after a hot run, is that fan speed two has not
> worked with the a/c off for quite some time. For example, if I am in stop
> and go traffic in the winter, and the engine gets hot enough, fan speed
> three will come on ( sounds like an aircraft taking off! ) until the
> coolant temp drops below it's preset threshold. The engine never overheats,
> so this has not been a problem from a practical point of view, so I have not
> done anything about it.
>
> However I usually have the a/c on about eight months out of the year,
> because it's hot and muggy in Houston even in the spring and fall. Fan speed
> one is sufficient to keep the coolant temp normal with the a/c on, and I'm
> not sure that fan speed two ever comes on when the a/c is kept on all the
> time.
>
> I'm thinking maybe I should check/replace the relay for fan speed two? If
> the temp sensor were the culprit, why would fan speed three operate at all?
> Am I on the right track?
>
> I'll send Steve Sears your greeting!
>
> Have a great Memorial Day weekend...
>
>
Sounds lie you are on the right track in diagnosing the fan. I would
suggest changing the thermo switch on the bottom of the radiator as it
is most likely the problem with speed two. It could also be the fan
speed two relay. You can easily unplug the thermo switch and jumper the
connections to operate speeds two and three. If Two doesn't run then its
the thermo switch.

However, given that your fan seems to be operating fairly well I would
guess that your battery drain is due to something else. You could try
pulling relays / fuses and checking for current draw with the ingition off.

 

Stephen Clark wrote:
> Thanks, Tony, I was vaguely aware of how the fan controls work. The only
> thing I have noticed that is abnormal, other than the fan coming on very
> briefly when the car is off after a hot run, is that fan speed two has not
> worked with the a/c off for quite some time. For example, if I am in stop
> and go traffic in the winter, and the engine gets hot enough, fan speed
> three will come on ( sounds like an aircraft taking off! ) until the
> coolant temp drops below it's preset threshold. The engine never overheats,
> so this has not been a problem from a practical point of view, so I have not
> done anything about it.
>
> However I usually have the a/c on about eight months out of the year,
> because it's hot and muggy in Houston even in the spring and fall. Fan speed
> one is sufficient to keep the coolant temp normal with the a/c on, and I'm
> not sure that fan speed two ever comes on when the a/c is kept on all the
> time.
>
> I'm thinking maybe I should check/replace the relay for fan speed two? If
> the temp sensor were the culprit, why would fan speed three operate at all?
> Am I on the right track?
>
> I'll send Steve Sears your greeting!
>
> Have a great Memorial Day weekend...
>
>
Sounds lie you are on the right track in diagnosing the fan. I would
suggest changing the thermo switch on the bottom of the radiator as it
is most likely the problem with speed two. It could also be the fan
speed two relay. You can easily unplug the thermo switch and jumper the
connections to operate speeds two and three. If Two doesn't run then its
the thermo switch.

However, given that your fan seems to be operating fairly well I would
guess that your battery drain is due to something else. You could try
pulling relays / fuses and checking for current draw with the ingition off.

 

Stephen Clark wrote:
> Thanks, Tony, I was vaguely aware of how the fan controls work. The only
> thing I have noticed that is abnormal, other than the fan coming on very
> briefly when the car is off after a hot run, is that fan speed two has not
> worked with the a/c off for quite some time. For example, if I am in stop
> and go traffic in the winter, and the engine gets hot enough, fan speed
> three will come on ( sounds like an aircraft taking off! ) until the
> coolant temp drops below it's preset threshold. The engine never overheats,
> so this has not been a problem from a practical point of view, so I have not
> done anything about it.
>
> However I usually have the a/c on about eight months out of the year,
> because it's hot and muggy in Houston even in the spring and fall. Fan speed
> one is sufficient to keep the coolant temp normal with the a/c on, and I'm
> not sure that fan speed two ever comes on when the a/c is kept on all the
> time.
>
> I'm thinking maybe I should check/replace the relay for fan speed two? If
> the temp sensor were the culprit, why would fan speed three operate at all?
> Am I on the right track?
>
> I'll send Steve Sears your greeting!
>
> Have a great Memorial Day weekend...
>
>
Sounds lie you are on the right track in diagnosing the fan. I would
suggest changing the thermo switch on the bottom of the radiator as it
is most likely the problem with speed two. It could also be the fan
speed two relay. You can easily unplug the thermo switch and jumper the
connections to operate speeds two and three. If Two doesn't run then its
the thermo switch.

However, given that your fan seems to be operating fairly well I would
guess that your battery drain is due to something else. You could try
pulling relays / fuses and checking for current draw with the ingition off.