05 STS cooling fans dead??

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kevm14
Posts: 13795
Joined: Wed Oct 23, 2013 10:28 pm

05 STS cooling fans dead??

Post by kevm14 » Sat Oct 19, 2019 1:53 pm

While I had the Tech 2 out I decided to command the low and high speed on the front aux cooling fans. I heard nothing. Long story short, the fuses are good and I think the relays are good. After reaching in and trying to poke the blades with a screwdriver it appears that both fans are completely frozen!! I had never heard them run before so I just wanted to test them while I was playing with the Tech 2. Didn't expect this. Anyway, I am guessing that especially since they sit in front of the A/C condenser and likely never turn on (this car has mechanical fan), they just...aged and then froze. Strange. It is possible that these have been frozen for years. No real way to know.

Not really an emergency this time of year (I've been through many summers, and some hot weather, so evidently they really are never needed) so I'll put this on the long list of stuff that I may get to at some point.

There is no picture but RockAuto seems to have the fans for $113.79 which isn't too bad. I'd have to remove the front bumper cover of course but I sure know how to do that by now...

The cheapest ones with a picture that shows the correct fans is Spectra at $153.79.
https://www.rockauto.com/en/moreinfo.ph ... 42&jsn=513

Actually, that AC Delco is not the right fan.

$154 is kind of steep for something that seems to be non-critical. I may just sort of pass on this for now....which is hard for me, because I like fans.

kevm14
Posts: 13795
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS cooling fans dead??

Post by kevm14 » Sat Oct 19, 2019 2:12 pm

Here is what the FSM says about the fan operation (also our SRX has the same cooling system - I should see if those are frozen, too):
Cooling Fan Control - Three Fan System
The engine cooling fan system consists of a mechanical fan, 2 electrical pusher-type cooling fans, and 3 fan relays. The low speed, high speed, and series parallel (S/P) relays are arranged in an S/P configuration that allows the engine control module (ECM) to operate the left cooling fan and right cooling fan together, at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G104.

During low speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit, to the left cooling fan. The ground path for the left cooling fan is through the cooling fan S/P relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the ECM supplies a ground path for the high speed fan relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan S/P relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time, the high speed fan relay coil is energized closing the relay contacts, and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.

The ECM commands the low speed fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 94.5°C (202°F).

• A/C refrigerant pressure exceeds 1447 kPa (210 psi).

• After the vehicle is shut OFF, if the engine coolant temperature at key-off is greater than 101°C (214°F), the low speed fans will run for a minimum of 60 seconds. After 60 seconds, if the coolant temperature drops below 101°C (214°F), the fans will shut OFF. The fans will automatically shut OFF after 4 minutes, regardless of coolant temperature.

The ECM commands the high speed fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 104.25°C (220°F).

• A/C refrigerant pressure exceeds 1824 kPa (265 psi).

• When certain DTCs set

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed, if required. This ensures idle stability by preventing the fans from cycling between high and low speed.
Interesting. So I could see them running in some conditions. There is also an after-cooling feature where they run in low speed if the engine is greater than 214F at key off. I am not sure I've met the conditions for high speed which is 220F and 265 psi on the high side. Those are fairly severe conditions considering the engine has a mechanical fan that turns all the time. But I probably have met the criteria for low speed. Meh, I still do not consider this any kind of emergency. I will at least forget about it until spring I bet.

kevm14
Posts: 13795
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS cooling fans dead??

Post by kevm14 » Sat Mar 07, 2020 2:48 pm

At the risk of confusing myself later, while I had the Tech 2 on the SRX, I decided to command the auxiliary electric fans to see if they worked (the SRX has the same fans as the STS).

It can apparently command the left, right or both fans. The driver's side fan seemed good. However the passenger side fan seemed like it had a bearing issue or something. But I let them both run with the car idling for 5 or 6 minutes. It seemed to help it. I'm guessing that these fans don't run very often and they are in front of the A/C condenser exposed to all road conditions (at the bottom, too). Not ideal. Hopefully I helped by running them for a while.

Still no plans to replace the fans on my STS. The SRX should have considerably more load on the A/C system given the larger interior volume with rear A/C, Ultraview roof, rear glass roof and black interior. The STS is white, with a light interior (and is not a wagon).

Also, lol:
kevm14 wrote:
Sat Oct 19, 2019 2:12 pm
I will at least forget about it until spring I bet.

kevm14
Posts: 13795
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS cooling fans dead??

Post by kevm14 » Sat Mar 07, 2020 2:58 pm

Looking at the fan control stuff again...and not sure if the SRX is different but probably not.
The ECM commands the low speed fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 94.5°C (202°F).

• A/C refrigerant pressure exceeds 1447 kPa (210 psi).

• After the vehicle is shut OFF, if the engine coolant temperature at key-off is greater than 101°C (214°F), the low speed fans will run for a minimum of 60 seconds. After 60 seconds, if the coolant temperature drops below 101°C (214°F), the fans will shut OFF. The fans will automatically shut OFF after 4 minutes, regardless of coolant temperature
Right so that's probably the driver's side fan. I think these conditions aren't that extreme so that fan probably runs under hot conditions with A/C use. If so, that explains why it seemed fine in the SRX (not sure why both are frozen in the STS though). The passenger side fan is probably added as "high speed" and those conditions are definitely more severe:
The ECM commands the high speed fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 104.25°C (220°F).

• A/C refrigerant pressure exceeds 1824 kPa (265 psi).

• When certain DTCs set

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed, if required. This ensures idle stability by preventing the fans from cycling between high and low speed.
This makes me want to replace them on the STS...hmm.

kevm14
Posts: 13795
Joined: Wed Oct 23, 2013 10:28 pm

Re: 05 STS cooling fans dead??

Post by kevm14 » Sat Mar 07, 2020 3:17 pm

For a more reasonable $65, I found this:
https://www.ebay.com/itm/Radiator-Fan-M ... SwaShdzD7n

I asked to confirm that they are the aux fans (I think they are by description) and if both spin freely (ideally, they have been tested).

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