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Radiator/Cooling fans - power, motor, or relay issue?

22535 Views 9 Replies 5 Participants Last post by  bigboost
Greetings all -

Just polling the masses to see if anyone has come across this issue before. My 93 SE (188k mi) was having some cooling issues recently. On highway speeds the temps were in the middle, but as soon as I hit traffic the temps would slowly rise. The other day the needle got near the "H" and boiled coolant over into the overfill tank because it was idling in the driveway. After some research I narrowed the issue down to either the thermostat or a radiator issue. Of course, no leaks were going on anywhere so I thought it might be the thermostat. The waterpump is about 2 years new. I changed the thermostat out yesterday (real PITA) - still the same issue. Of course, this time while hovering over the engine bay I noticed the fans never kicked on and a lightbulb instantly went off in my head. Oddly, if I shook the radiator around the driver's side fan would rotate - notice I didn't say "run", but rotate. Once I quit shaking it or tapping on the fan guard, the fan would simply quit rotating. It's almost as if either the fan motor is dying/dead or there is not enough voltage being supplied. The passenger side fan never turned at all. I checked and reseated both the relays and fan connectors. If I were to check voltages, would I simply touch the nodes of a voltmeter on the fan connector ends? Would the Haynes suggest a point to check voltages?

Given the above scenario, what would be your thoughts on what's causing the issue? A: bad fan motors, B: bad relays, C: bad connection or low voltage, D: OTHER

Thank you in advance for any suggestions you might have.
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You will find that there are not built in test points, so if you are serious about checking the voltage you can split the wire and probe the conductors, be careful not to cut them.
you can use any ground, so just open the 12v supply, with the FAN on, ie under load.
Yes just touch the conductor and measure the voltage, should be close to 13 - 14 V with the engine running
Then wrap with electrical tape. It helps if you do this where it can be covered with the harness.
However, my first suspect is the fans, these are mechanical and at 188k I am not surprised they are dieing.
On my manual 97 both fans turn on when cold with the A/c ( cold is a relative term on a 104 degree day in Dallas) and off when i turn the A/C off.
So i suggest you turn the A/C on and unplug the fans and probe the connector.
use a grnd on the chassis, and you should find 12V on at least one pin. if not check the relay, and last is the ECU see EC-430
yes shows the schmatic. I found it difficult to find much in the FSM. Page number may varry if you have dffernt year FSM.
dont forget you can buy replacement fans from the wreacker yards or a generic from places like autozone as well as the specific fit ones.
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