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Re: cooling fan Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 29 Apr 2004 06:14:02
In Reply to: cooling fan, jennifer, Wed, 28 Apr 2004 23:35:44 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Don't apologize about it being long - wait till you read this tome.
Wire 12 volts to the fan and see if it runs. Use fat wire - that fan takes a lot of current. Touch 12 volts to the Green wire on the resistor on the fan and see if it runs. If it doesn't, it could still be a bad ground for the fan. I assume all fuses have been checked. There are a lot of connectors and a ground in there, and the fan takes a lot of current (as stated) to start up. One bad connection, and it won't allow enough current to start the fan. But if you measure the connection with a meter, you may see a low resistance (an ohm or two).
Of course, it could be a bad thermostat. The radiator fan runs when the radiator gets hot. The thermostat is the valve that moves hot coolant from the engine to the radiator. If the thermostat is sticking, it'll never let hot coolant get to the radiator, so the engine runs hot and the radiator runs cool, and the fan never comes on.
If the car is moving above about 20 mph, normal airflow is equal to that of the radiator fan. The fan is there to provide airflow when moving slowly or stuck in traffice. If you're having overheating issues when driving along at speed, the problem isn't the fan - most likely the thermostat.
An 82C thermostat is a nice idea, but it's only half the battle. To get best results, you want an 82C thermostat and a 82C radiator fan switch (and working fan) Why? When the engine temp gets to 82C, the thermostat opens up and dumps that hot coolant into the radiator, and the return coolant should be nice and cool. So while driving around, your engine will be at 82C. There is really no advantage with this over the 89C stock thermostat. Now, if you have a 89C fan thermoswitch, and you get stuck in traffic, the coolant in the radiator can be 89 degrees (C) before the fan comes on. The engine thermostat opens at 82 and dumps coolant to the radiator, but the stuff coming back is 89C. The engine thermostat stays open. So if the fan thermoswitch is 89C, when stuck in traffic, it's the same as a 89C thermostat.
Removing the thermostat isn't the solution if the fan is bad. Again, all the fan does is replace the airflow missing when you're idling or going very slowly. With no thermostat the engine will run much cooler because it's throwing all coolant to the radiator right away. This isn't great for the engine, because if the engine doesn't get warm enough, the clearances aren't right, and you won't get the oil warm enough to boil off water that it collects. And if you get stuck in traffic, you'll still overheat - thermostat or no, there is something generating heat under the hood, and if there is no airflow, that heat won't get out.
Is the overheating a problem when driving along at speed? If so, replacing the thermostat is the first step.
posted by 192.249....
, Thu, 29 Apr 2004 06:14:02 <-- Viewing This Message, Fri, 30 Apr 2004 06:08:54
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