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Where are 94 SLS Cooling Fan Relays?


Jagmeister

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My 94 Seville SLS has started giving erratic cooling performance. I've owned it for 3 years now, it has 132K on it and normally runs right around 200 deg. The last couple of days it has been very erratic. It behaves itself for a while and then suddenly climbs up to toward 225. Then it will drop back down where it belongs. It got as high as 235 once. It is not throwing any DTC codes.

I want to go in and clean up the relay contacts and test the coolant temp sensor but don't know where either are located. Can someone get me in general vicinity?

Thanks,

Matt

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My 94 Seville SLS has started giving erratic cooling performance. I've owned it for 3 years now, it has 132K on it and normally runs right around 200 deg. The last couple of days it has been very erratic. It behaves itself for a while and then suddenly climbs up to toward 225. Then it will drop back down where it belongs. It got as high as 235 once. It is not throwing any DTC codes.

I want to go in and clean up the relay contacts and test the coolant temp sensor but don't know where either are located. Can someone get me in general vicinity?

Thanks,

Matt

I would also like to know where the coolant fan sensor is. We have a 1998 STS; last week, we noticed that the primary fan was not running; just the one that runs when the a/c is on was running. We changed the relay, but it did not help. Someone said to change the temp. sensor, but we don't know where it is!!!! Help!

My "other car"

100_05472.jpg

1968 Pontiac GTO, 400, 4 speed, 366 h.p., matching numbers car

*Get well soon, John Force!!!*

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I would also like to know where the coolant fan sensor is. We have a 1998 STS; last week, we noticed that the primary fan was not running; just the one that runs when the a/c is on was running. We changed the relay, but it did not help. Someone said to change the temp. sensor, but we don't know where it is!!!! Help!

Normal operation for a domestic USA '98 to '04 Seville is BOTH fans on low speed OR both fans on high speed. There would not be a 'primary' fan. Plus there are three relays involved with the low speed - high speed switching arrangement.

Sounds like you might have one failed fan motor.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I believe the fan relays are between the fans . There is no "coolant fan sensor". The sensor you are looking for I believe is the coolant temp sensor and If memory serves me correctly, I think it is under the intake manifold. Someone will correct me if I am wrong.

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I would also like to know where the coolant fan sensor is. We have a 1998 STS; last week, we noticed that the primary fan was not running; just the one that runs when the a/c is on was running. We changed the relay, but it did not help. Someone said to change the temp. sensor, but we don't know where it is!!!! Help!

Normal operation for a domestic USA '98 to '04 Seville is BOTH fans on low speed OR both fans on high speed. There would not be a 'primary' fan. Plus there are three relays involved with the low speed - high speed switching arrangement.

Sounds like you might have one failed fan motor.

Mea culpa.

I know better than to leap into a 1997 and prior discussion with 1998 and later information.

This part deserves to be moved to a new topic.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I believe the fan relays are between the fans . There is no "coolant fan sensor". The sensor you are looking for I believe is the coolant temp sensor and If memory serves me correctly, I think it is under the intake manifold. Someone will correct me if I am wrong.

The relays that we changed, according to the owners manual, were in a black box under the hood on the left side. I think he changed 3, may have been only two; he ordered the sensor from the local dealer, should get it today, but we did not know where it was located on the car. He took off the fan that is not running and tested the motor, and it did run; so I hope the sensor fixes it; if not, anybody else got any more ideas? He usually tries to fix our stuff himself, but he is a body and paint man by trade, only tinkers around as a mechanic; so far, he is only guessing as to what is causing the problem. The only thing I know for sure, is that the information system in the dash has not told me there is a problem, and I thought it knew everything!!!

My "other car"

100_05472.jpg

1968 Pontiac GTO, 400, 4 speed, 366 h.p., matching numbers car

*Get well soon, John Force!!!*

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The coolant temperature sensor (there is only one) is located on the right side cylinder head, at the back. As the engine is installed in the engine bay (sideways), it's on the driver's side corner of the engine. Not exactly easy to get to, but not a very trouble-prone part either. I would not suspect this sensor to be the problem. The PCM controls the fan relays, with inputs from the sensor. If at least one fan is running, the sensor is probably fine.

The fan relays, on most FWD Cadillacs, are mounted at the bottom of the radiator support. Basically, open the hood, look straight down between the two cooling fans, and you should see THREE relays down there. Those three relays control BOTH vans together at either HIGH or LOW speeds. If one relay is bad, that could possibly be the cause for one fan not working.

I believe a 1994 model should have this setup -- with the three relays mounted towards the bottom of the radiator.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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I assume this information is for a 1994 car. Do you have the same information for a 1998 STS?

My "other car"

100_05472.jpg

1968 Pontiac GTO, 400, 4 speed, 366 h.p., matching numbers car

*Get well soon, John Force!!!*

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I assume this information is for a 1994 car. Do you have the same information for a 1998 STS?

For '98 - '04 Seville, there are 3 relays in the underhood junction box (and if you are in the UK, that box could be anywhere Cadillac could make it fit for RH drive); the relays are labeled Cool Fan 1, Cool Fan 2, and Cool Fan S/P.

There are also two associated 30A fuses in that box labeled COOL FAN 1, and COOL FAN 2.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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My 94 Seville SLS has started giving erratic cooling performance. I've owned it for 3 years now, it has 132K on it and normally runs right around 200 deg. The last couple of days it has been very erratic. It behaves itself for a while and then suddenly climbs up to toward 225. Then it will drop back down where it belongs. It got as high as 235 once. It is not throwing any DTC codes.

I want to go in and clean up the relay contacts and test the coolant temp sensor but don't know where either are located. Can someone get me in general vicinity?

Thanks,

Matt

Matt,

I have read all the replies to date and have one comment to make. Your condition may be normal, depending on the operating ambient temperatures. My reasoning:

The thermostat, probably a 195 degree unit, shuld start to open at 195, be fully open within 10 degrees. If engine temp is not maintained by sufficient air flow, the electric fans are switched on, using the 3 relays everyone is aware of. (On your car they are 3 of the 4 big black relays, just in front of the fuse/relay center on the driver's side fender). The PCM tells the relays to close in the proper sequence. First, both fans are turned on by relays one and two, that wire the two fans in series, which results in both fans running at low speed. This happens at 209 degrees, as measured by the temp sender, mounted in the drivers end of the rear head. One wire, hard to see. The PCM, at 223 degrees, turns the other relay on, which takes the fans out of series and puts full voltage to each motor, so they are both running in high speed, with all three relays energised. Stationary, or in traffic, both fans on high, the engine temperature can continue to climb, this is NORMAL. Somewhere about 259 degrees , the PCM will cut off the AC, (on my car, it cuts out at 243 degrees) I have experienced this many times while waiting for my wife to come out of a store.

In any of the above conditions, you should NOT experience any water loss and the engine will run just fine. If you are having to add water, I would first replace the coolant tank cap, then very carefuly look for leaks around the radiator and the water pump. Also check the small aux belt that drives the water pump. If the tensioner is allowing the pump drive to slip, you have a problem.

Finally, the vent line steel pipe just above the thermostat housing, has been the subject of recent discussions. The hole is about 3/16" and has a tendency to clog, especially if some brands of antifreeze and/or stopleak have been used. The vent line, which returns air to the coolant tank, must also be clear.

Here in Phoenix, moving at STEADY freeway speeds with ambient about 100 degrees, On my Eldorado, the coolant temp is about 205. This is with new hoses, clean vent, and a new radiator last year.

Good luck,

Jim in Phoenix

Jim in Phoenix

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