Fan Problems?need advice

[V6-Sauce]

It was running hot at idle with one tab missing from the resistor and a one wire missing, I connected all wires to the 2nd tab on the resistor..Not much else more I can do, but buy a new resistor with 2 tabs. The fan & Resistor, one wire for low speed the other for high speed, that's it. There's nothing more to it. I didn't start the car but from the test, Touching both pins with a wire& ground the fans came on, before only one pin fan came on.

 

[V6-Sauce]

Maybe for the price of the discontinued Resistor. I should just get a new dual fan setup, might cool better compare to stock with a 3 row HE rebuild rad?

 

[mikestertwo]

I thought the car was running hot at idle? You always had a complete electrical fan circuit, if only on high speed, so I don't see how this fixed the problem.

The high speed fan is controlled by the thermal switch on the intake manifold, A/C switch or the delay relay. The thermal switch doesn't activate until 226*F. By then the motor is close to overheating. It will take some time for the high speed fan to start cooling the motor down. That's assuming the thermal switch is hooked up and working.

 

[V6-Sauce]

I'II see if it kicks on at 227*, if it does, I need a new resistor for the low speed fan to come on sooner.

 

[mikestertwo]

I'II see if it kicks on at 227*, if it does, I need a new resistor for the low speed fan to come on sooner.

The computer controls the low speed which is determined by the prom chip program. By bypassing the resistor the fan will come on at whatever temperature your chip is set for. It just will be in high speed mode. Some people run like that all the time. To test the high speed thermal switch circuit just pull the connector off of the thermal switch and ground it. If the fan comes on in high speed the circuit is good. Then if you want you could run your test but I don't like getting the engine that hot. Just make sure the fan comes on when the computer commands it.

 

[GNRick]

When my fans weren't coming on until 200 degress plus, but the fan circuit was good, it was the fan switch that failed.

 

[mikestertwo]

When my fans weren't coming on until 200 degress plus, but the fan circuit was good, it was the fan switch that failed.

Then you were not wired like a stock setup. The computer should run the fan in low speed. The switch closes at 226*F to run the fan in high speed only.

 

[Linewalker]

"Just jump the resistor out and remove it from the loop. I have no idea why someone would want a fan to run slow with the side effect of a resistor converting fan speed into heat."

Why did the Buick engineers even use a resistor then? Emissions maybe??

 

[mikestertwo]

"Just jump the resistor out and remove it from the loop. I have no idea why someone would want a fan to run slow with the side effect of a resistor converting fan speed into heat."
Why did the Buick engineers even use a resistor then? Emissions maybe??

My take on the reason is two fold. 1) The engineers determined the low speed was sufficient to keep the engine cool under most circumstances. If it wasn't in some cases like when you run the air conditioner or the engine temps start getting too high they have the backup circuit...the high speed. 2) The resistor limits the in-rush current when the fan first starts. Starting the fan from a dead stop takes a lot of current. The resistor will limit the current and extend the life of the contacts on the relay. In my business it's called a "soft start circuit".

 

[earlbrown]

"Just jump the resistor out and remove it from the loop. I have no idea why someone would want a fan to run slow with the side effect of a resistor converting fan speed into heat."

Why did the Buick engineers even use a resistor then? Emissions maybe??

They also thought we need to run 12 pounds of boost.


Having a low speed will make less noise and it's easier to cool a stock 300hp engine than what most TRs have today. Not to mention those engineers installed that circuit on a new radiator. It amazed me how many clogged up stock units are still in cars today.

 

[V6-Sauce]

ok, started the car the other day. I doubled up all the wire to one side of the resistor(The otherside of the resistor is broken) Anyways the fan doesn't come on at all now, I tryed testing with a wire to ground and testing the pins on the AC compressor switch plug. Fan don't come on at all, The relays click but fans don't come on. I checked the 5 amp gage fuse under the steering wheel (that says relay), looks ok. Any idea's? Also I tryed disconnecting the fan plug and with a wire one end on pos+ on the battery and other end on fan plug pins. nothing comes on?

 

[turbo89]

ok, started the car the other day. I doubled up all the wire to one side of the resistor(The otherside of the resistor is broken) Anyways the fan doesn't come on at all now, I tryed testing with a wire to ground and testing the pins on the AC compressor switch plug. Fan don't come on at all, The relays click but fans don't come on. I checked the 5 amp gage fuse other the steering wheel (that says relay), looks ok. Any idea's? Also I tryed disconnecting the fan plug and with a wire one end on pos+ on the battery and other end on fan plug pins. nothing comes on?

ok so you put 12v+ from the battery on 1 lug on the fan, and 12v- from the battery on the other lug on the fan and got nothing ? ... tells me the fan is toast

 

[V6-Sauce]

yeah, I did this test from the fan plug and pos+ side on battery with a wire. Afterwards when I connected the fan plug back to the engine harness plug, fan turned on for like a second than turned off?

 

[turbo89]

yeah, I did this test from the fan plug and pos+ side on battery with a wire. Afterwards when I connected the fan plug back to the engine harness plug, fan turned on for like a second than turned off?

verify the FAN first ... 2 lugs on it .. hook direct to 12 V source ( need 2 wires for this )

if the fan works then grab a voltmeter and move to the fan harness and check for power on the one leg and check for ground on the other with the relay tripped

basically break down the testing to 1) FAN operation itself, 2) POWER and ground at the FAN HARNESS with relay jumpered 3) Signal to trip fan relay

 

[V6-Sauce]

I'II try it...

 

[V6-Sauce]

1. Ok, Fan plug with 2 wires connected directly to battery + and - , fan works on high speed. 2. Engine harness plug with voltmeter ground and power, showed 0.03-0.04 on dc/volts. 3. AC pressure switch plug, one wire test to ground...fans don't come on. But relays click, and tested AC pressure switch plug with mutimeter, there's 12volts. You think it might be the fan coolant temp sensor or connectors from the relays?

 

[mikestertwo]

1. Ok, Fan plug with 2 wires connected directly to battery + and - , fan works on high speed. 2. Engine harness plug with voltmeter ground and power, showed 0.03-0.04 on dc/volts. 3. AC pressure switch plug, one wire test to ground...fans don't come on. But relays click, and tested AC pressure switch plug with mutimeter, there's 12volts. You think it might be the fan coolant temp sensor or connectors from the relays?

I would say you wired something wrong when you moved the wires. Can you post a picture of the wiring at the fan, resistor and the 3 pin connector?

 

[V6-Sauce]

yes, I can...thx for answering...It can't be the chip, I sent it back already and it was checked. It works perfectly on the scanmaster, Numbers are where it should be. Accept the fans turning on. I even made sure the chip was install property. The ECM(Computer box unpluged), I had it sent out and checked out a couple of years ago with the stock chip installed, checked out OK. everything's good. The ecm reads the temp raising with scanmaster and gauge(gauge reads higher).

The Fan Resistor, There's 2 terimals for wires. One side rusted out and broke off. Connected all the wires on the resistor to the otherside on the Resistor.. I did a test with the fan alone with the fan plug straight to battery, The fan works. Just not when its connected to the engine harness. I'm thinking maybe the temp sensor or connectors to relays(The relays are new). I pulled all the fuses inside the the car and checked if anything is brown, it's all good.

The AC compressor switch plug when it's disconnected & ignition on and test with one wire on pin's on the connector plug with the other end of wire to ground like sheet metal, Relays click but Fan don't turn on. Checked volts with multimeter on plug, there's 12Volts?

 

[mr84ss]

Sent from my LGMS631 using Tapatalk

 

[turbo89]

yes, I can...thx for answering...It can't be the chip, I sent it back already and it was checked. It works perfectly on the scanmaster, Numbers are where it should be. Accept the fans turning on. I even made sure the chip was install property. The ECM(Computer box unpluged), I had it sent out and checked out a couple of years ago with the stock chip installed, checked out OK. everything's good. The ecm reads the temp raising with scanmaster and gauge(gauge reads higher).

The Fan Resistor, There's 2 terimals for wires. One side rusted out and broke off. Connected all the wires on the resistor to the otherside on the Resistor.. I did a test with the fan alone with the fan plug straight to battery, The fan works. Just not when its connected to the engine harness. I'm thinking maybe the temp sensor or connectors to relays(The relays are new). I pulled all the fuses inside the the car and checked if anything is brown, it's all good.

The AC compressor switch plug when it's disconnected & ignition on and test with one wire on pin's on the connector plug with the other end of wire to ground like sheet metal, Relays click but Fan don't turn on. Checked volts with multimeter on plug, there's 12Volts?

ok so the fan works .. verify if you have ground on the fan harness when you jumper the relay