Fan does not come on.

[MN Ben]

the 88 bonneville w/ the 3800 engine has a overheating problem.

A new fan motor was purchased but the fan still does not kick in. I do not know why. I cannot find a blown fuse. What does the white block that the red wire runs through on the fan do?

Ben

[myfirstbonnie]

IIRC. That is for the high / low speed. Ours don't have 2 fans, so when the ac is on it kicks it into a high speed.

[gmman]

assuming that you have vin 3 without heavy duty cooling; if so could be:

1. there is a coolant fan relay after fuse block fuse 6 that is energized by the following conditions: (a) air conditioning on or (b) engine temp above 208 degrees f. both conditions sensed by ecm. also if engine temp above 230 degrees relay is energized by temp switch.

2. there is a fusible link (wire that melts if subjected to extreme current) that feeds 12 v to the coolant fan relay contacts and then to the coolant fan motor.

3. note that you have to meet 2 or 3 conditions before fan is supposed to come on.

[MN Ben]

there is not a 3 in the vin #. Which digit are you referring to? 1G2HX54C5JW252880

[grey3800]

the 88 bonneville w/ the 3800 engine has a overheating problem.

A new fan motor was purchased but the fan still does not kick in. I do not know why. I cannot find a blown fuse. What does the white block that the red wire runs through on the fan do?

Ben

If that's your vin, then you have the vin C engine. The white block you are referring to is the resistorblock, used to make the fan run in low speed (current through resistor) and high speed (current not through resistor). Theres a good chance that all the heat and vibration over the years has cracked the resistor and it no longer allows current to flow through it.

The low speed kicks on for A/C and when temp gets above 200ish degs. Ive only seen it kick on HIGH speed once, when my waterpump broke and engine temp got VERY hot. Check all fuse centers, and relays (even swapping relays checking for bad contacts).

If you can, perhaps remove the electrical connector and try applying 12V directly to the fan motor to see if it will kick on with and without the resistor in place.

[gmman]

grey 3800 clears which vin you have. where you have c, there would have been a 3. there is a further variation in that vin c comes with or without heavy duty cooling. if you only have one fan, then you have vin c without heavy duty cooling.

in that case there are two relays involved. one for low speed fan (as grey 3800 pointed out current is routed thru a resistor) and one for high speed fan (no resistor).

the low speed operation is controlled by the ecm depending upon air conditionng on and engine temp above 208 degrees f.

high speed operation is dependent whether ac compressor pressure is above 300 psi.

good luck.

[MN Ben]

Thank you guys. I'll do some more checking Monday. The main issue is that the car is getting abnormally hot and this happens when it slows down in town and at a stop sign. I will also take a hose to the radiator and AC condenser. I have heard high temps at slow speeds tend to point to the radiator. I will turn on the AC tomorrow to see if the fan kicks in.

Things were great after a new water pump was put in. Two days ago the thing just starts getting hot. Today I back flushed it through the heater core hose and with the (good) thermostat removed.

Ben

[grey3800]

Consider spending 5 bucks and throw in a new thermostat. On my 88, i had the non-heavy duty cooling, over the years i had many thermostats put in. With one that was stuck open, my engine would stay below 130*, with one stuck halfway open all the time it stayed around 180*, both no matter what driving and weather conditions. With a properly working stat the temp stayed in the range it was supposed to 195 to 210.

Also you mentioned recently placing the water pump, did you remember to purge the system of air? (screw valve on top of thermostat housing flange). Since its been several days, theres a good chance the air in the system has made it's way to the top of the system, might as well purge what, if any air that might be there (do it when engine warm).

Lets us know...

[Alibi]

Just an FYI, No screw valve on top of the LN3 thermostat neck

[MN Ben]

I did not see a screw to release air. I got busy the last 2 days but this heat thing is on my short list.

Ben

[grey3800]

Just an FYI, No screw valve on top of the LN3 thermostat neck

MY bad, ive been under the hood of my 93 too much now im forgeting more of the little things