Question: Aux fan not working

[ken mohr]

The thermal switch for the aux fan is between 1 & 3 spark plugs but if the main fan will not bring the temp down the smaller aux fan won't come close to bringing the temp down. Something else is causing the temp problem.

 

[gmjunkie]

The main fan needs to come on either with the A/C or when the car hits 228 ( ish )

the AUX fan only has 1 control which is the sender on the side of the block.

The thermal switch for the aux fan is between 1 & 3 spark plugs but if the main fan will not bring the temp down the smaller aux fan won't come close to bringing the temp down. Something else is causing the temp problem.

And I'd like to add,that a lower temp thermostat isn't going to make it run any cooler either!! The thermostat only controls the minimum operating temperature,and will have no effect on higher temps!!(Unless it happens to be faulty and is stuck shut or opening up too slow!!)
Only the condition of your Cooling System,Mechanical or Electronic failures will effect the high end temps!!(Radiator,Water Pump,Head Gaskets,Belts,Hoses,Ignition Timing,Cooling System Obstructions!)

 

[gmhowe]

Ok here is the history, Water Pump and Radiator replaced 18 months ago.
Engine rebuilt in February of this year, no issues during the 500 miles before taking it back for the breaking check. Everything checked out fine during the checkup except the Fuel Pressure Regulator blew the diaphram so that was replaced and they put in the 160 thermostat due to the chip I have in the car. brought it home 30 miles and ran fine, next day while waiting to pick up my daughter is when it started the 240 degree stuff. Turned off the ac and it went back down to 220 but it was 114 that day here in phoenix. Havent driven it since, but got my 96 back after the ac compressor clutch was rebuilt. am gonna try and do some electrical diagnostics this weekend. Will update accordingly.
Thanx for all your help
Gordon

 

[vetteoz]

The thermal switch for the aux fan is between 1 & 3 spark plugs.

On '85 it is between # 6 & 8

 

[vetteoz]

while waiting to pick up my daughter is when it started the 240 degree stuff. Turned off the ac and it went back down to 220 but it was 114 that day here in phoenix.

Under those conditions I really don't see a problem.

You are sitting idling in extreme outside heat with the A/c on. The outside cooling air into the condensor is at 114 ( probably higher due to low level air heated by road surface going into radiator ducting) then you are adding the extra heat from the A/c condensor to the air trying to cool the radiator and expecting it to maintain normal running temp?
The fact the temp came down to normal when you turned the A/c off tells you something.