Temp is 225 and fans not kicking on. Replaced the temp. sending unit (with the wires that sends the signal to the ecm). I thought that fixed it but it didn't. If the thermostat is sticking could it be hot and the ecm not command the fans to come on? Car is just idling. I even got a new chip from turbobob when this was happening last time. I know the fans work because they come on occasionnaly. Thanks.
Car is hot and fans not on
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turbo96max
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check the connector where the fans connect to the factory harness. i have the upgraded dual fans w relay and harness, over time it melted the thick wire connection inside. just made my own connection now its good. see if the power if getting accross with the car running , or jump the connector just to test.
salvageV6
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Relay contacts can become intermittant.
You could stick a needle through each green thinner wire on the fan relays which is the trigger ground lead and attach a clip lead to the needle and ground it, the relay should click on and the low and high speed both will trigger that way with the thinner green and green/yellow stripe lead on the two relays.
If they are no longer intermittant try checking the RLYS fuse.
At 225 degreees both the low speed and the high speed relay should be activated.
Ground trigger relay tests are done with the engine idleing or IGN key ON car off.
You could stick a needle through each green thinner wire on the fan relays which is the trigger ground lead and attach a clip lead to the needle and ground it, the relay should click on and the low and high speed both will trigger that way with the thinner green and green/yellow stripe lead on the two relays.
If they are no longer intermittant try checking the RLYS fuse.
At 225 degreees both the low speed and the high speed relay should be activated.
Ground trigger relay tests are done with the engine idleing or IGN key ON car off.
My car did that a few years ago and it ended up being a bad Temp Fan Control Sensor, it's located on the left side of the intake manifold, towards the front, directly under the throttle body linkage. The sensor sits vertically and has a single green wire going to it. Hope this helps.
I think that is the one I just replaced today. It sends the signal to the temp. gauage in the dash. After I shut the car off I found a huge coolant spill under the car. Couldn't tell where it was coming from but pretty sure it was not the sensor that I just replaced with the single green wire. So could it be the water pump.... and if so would the fans not come on . Could I have more than one issue? BTW the water pump is less than 6 months old. Will perform the other tests.
There are 3 temp sensors on our cars, 1) sensor is located by the thermostat housing sitting horizontally ( Coolant Dash Light Switch ), 2) sensor is located directly under the throttle body linkage sitting vertically with a single green wire going to it ( Temperature Fan Control Sensor ) , 3) sensor is located directly under sensor #2 sitting horizontally with two wires going to it (Coolant Temperature ECM Sensor ).There are also three fan relays they are attached to the drivers side inner fender, 1) the largest of the three is the ( Fan Delay Relay ) it has a built in timer which will activate the low speed fan if the coolant temp is above 226F degrees when the car is turned off. 2) the middle relay is smaller than the first and is the ( High Speed Relay ) it is controlled by the air conditioning high pressure switch and the ECM . It's is activated at a coolant temp of 226F or an air conditioning refrigerant pressure of 275 psi. 3) relay is the same size as the second one it's is the ( Low Speed Relay ) it is controlled by the ECM and the air conditioning high pressure switch. If I remember correctly if you remove the wire from the #2 coolant sensor and ground it out,( with the key on motor off) it should turn on the fan, if it doesn't turn on check all wire connections ( look for broken wires, corrosion and grounds ) if all is good I would then replace the low speed fan relay . After doing this ground out the wire to #2 coolant sensor again key on motor off it should turn on the fan.
salvageV6
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There's way too much mis-information here:
Here's how it really works along with the factory service manual diagram.
http://www.vortexbuicks-etc.com/fan.htm
Here's how it really works along with the factory service manual diagram.
http://www.vortexbuicks-etc.com/fan.htm
I appreciate all the help. I'm currently remodeling a house to sell it....paint, counter tops, etc. so I won't have too much time to devote to the gn. My gut feeling is that the water pump was getting weak and now crapped out. Anybody agree with me? Coolant leaked out when I shut the car off. Huge spill. As for the relays, can they get weak or is it good/no good? Fans have come on in the past even when the car was hot but then they shut off before the temp came down to 185. Or could it be the thermostat?
salvageV6
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They can be intermittant but usually will fail full off, or on in the case of the delay relay.
It's easy to test the trigger green wires as mentioned.
If you don't like the idea of sticking a needle through the trigger wire you can test the high speed one by disconnecting the single wire plug at the temp. switch for the high speed relay and touch a wire going to a good ground to the connector pin, the fan should come on high speed immediately if the IGN key is ON.
Verifying if the relays and fan is operating via the green trigger wires is about a 15 minute job at most.
It's easy to test the trigger green wires as mentioned.
If you don't like the idea of sticking a needle through the trigger wire you can test the high speed one by disconnecting the single wire plug at the temp. switch for the high speed relay and touch a wire going to a good ground to the connector pin, the fan should come on high speed immediately if the IGN key is ON.
Verifying if the relays and fan is operating via the green trigger wires is about a 15 minute job at most.
groumoutis
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The water pump and the thermostat do not control the fans. It could have came out of the overflow tank. Like everyone else has suggested you have an electrical problem that is causing the fans to not turn on. Without the fans pulling air acrossed the radiator the temp will skyrocket cause excessive pressure in the coolant system which then causes the radiator. Ap to release the pressure by sending coolant to the overflow. If the overflow gets too full it will dump on the ground. Check the electrical connections and forget the pump and thermostat for no and get the fans to kick on. Does your a/c work? If so use the a/c to kick the fan on.
Ok I just went out to the car and turned on the A/C. The fans came on high. Spill definitely was not from the overflow. So if the fans come on with the A/C does this eliminate any issues with the fan relays? Could still be a temperature sensor, correct? To test the water pump (or any coolant leaks) do you pressurize the radiator and see where the coolant leaks out from? My heater fan failed after one year (made by VDO in China) so it would not surprise me if the water pump failed in 6 months. Seems like I've had other parts fail within a year.
I read thru this and it is certainly informative. Will read it again this week and test the sensors like Steve says.There's way too much mis-information here:
Here's how it really works along with the factory service manual diagram.
http://www.vortexbuicks-etc.com/fan.htm
Sinisturbo
Maximum Entropy
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Replace the Low speed fan sensor it is located directly under sensor #2 sitting horizontally with TWO WIRES going to it (Coolant Temperature ECM Sensor ). The one you replace is the hi speed fan sensor.
groumoutis
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As far as the leak goes, it could be the hose that is next to the thermostat housing. The best thing to do is find the source of the leak before throwing parts at the car. If the temp got up to 225 you could have softened a hose up enough to get it to rupture. I had this happen on a Dodge Dakota the day I got out of the navy. A $10 hose is a lot better than replacing a water pump. Since that hose is above the pump it will run down and around the water pump and it will appear to look like the pump is leaking.
You can take the high speed relay out of the equation. It sounds like it is a sensor to me. You can swap the high speed relay with the low speed one and see if the fan comes on again with the a/c and that will tell you if the low speed relay is good or not.
You can take the high speed relay out of the equation. It sounds like it is a sensor to me. You can swap the high speed relay with the low speed one and see if the fan comes on again with the a/c and that will tell you if the low speed relay is good or not.
I didn't know there is a low speed and high speed sensor. Are you referring to the relays?
salvageV6
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The ECM controls the low speed operation by the value set in the chip.
Read the link to the factory service manual the whole diagram is on the page.
I doubt your low speed relay and fan turn on point are being met at 160 to 180 degrees depending upon your chip maker. Hence the car can hit 200 degrees quickly and easily.
The high speed doesn't turn on until about 215 degrees with the sensor in the intake.
You could purchase a Caspers plug and play HI/LOW speed switch that uses the A/C triggers to test the wiring but again that would still require some work.
Read the link to the factory service manual the whole diagram is on the page.
I doubt your low speed relay and fan turn on point are being met at 160 to 180 degrees depending upon your chip maker. Hence the car can hit 200 degrees quickly and easily.
The high speed doesn't turn on until about 215 degrees with the sensor in the intake.
You could purchase a Caspers plug and play HI/LOW speed switch that uses the A/C triggers to test the wiring but again that would still require some work.
groumoutis
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Did you swap the high speed and low speed relays to make sure the low speed relay works? Have you checked the resistor to see if it is cracked?
