Intermittent Fan Problem

[Top Speed]

Took the Buick out yesterday for a drive.    On the way back I noticed the engine running hotter than usual, and by the time I pulled into the garage and popped the hood it was 230 F.  When I popped the hood to check, both fans ( I have dual Spal fans) were not running.  I have a manual switch that can turn the fan on and it worked.  Later I started the car and let it warm up and the fans cycled properly.  It wasn't until later that I realized that I could check the ecm sensor by using the scan master.  I will check to make sure it is working correctly next time I take her for a spin.  Other than that, isn't' there a back up switch that is supposed to turn the fan on?  I need to read up on the fan wiring diagram.

[Steve Wood]

the ecm turns the low speed circuit on when it sees the temp the chip is programmed on.  High speed is dependent upon AC pressure, or coolant temp switch.

Not knowing how you wired your spals, I cannot give you much help.  Here is the diagram and some troubleshootin g tips

http://www.vortexbuicks-etc.com/fan.htm

[Top Speed]

The Spals use a harness that John Spina made for me.   They are hot wired and tie into stock harness connector.   I still suspect the stock sensor but I did not get to go for a ride yet, since I had to cut the weeds first.

[Steve Wood]

if the clt temp looks normal, then it is not the sensor.  Sounds like a relay problem to me.

I made my own harness and ran one fan off the low speed and one off the high speed....too much load for one relay it seems to me

[Top Speed]

Each fan has its own relay.  They both appear to be controlled off of the low speed relay. There is a delay module for starting the fans so they both don't start at the same time. 

[ULYCYC]

Sounds like John uses the stock low speed relay only as a trigger for the spal relays. When up to turn-on temp see if the stock relay sends a ground or hot signal ( John could have wired it either way)  to the spal harness.

[Top Speed]

Went for a ride today and fans worked fine.  Checked the coolant temp readout on the scanmaster and it was matching right up with my Autometer guage.  I will just have to keep an eye out and see if it happens again!

[Top Speed]

OK just went for another ride and on the way back the fans stopped working again.  Coolant temperature sensor is working fine.   Back in the garage with the engine off, I tested the manual switch and I could hear a relay chattering.  Checked it out and the new fan harness relay was the one chattering.  Guess I need to call John and see what he thinks.  Sounds like a bad relay to me.

[Steve Wood]

pull the relay out, use a jumper from hot to hot on the connector and see if the fan runs...if so, then it would seem to be the relay

[Top Speed]

I think I found part of the problem.  The relays on the kit are the blue 30 amp type.  The specs for the fan say up to 40+ amps for the 12" Spals that I have. 

[Top Speed]

OK, I replaced the relays with new 40A units and that seems to have solved the problem.