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How fans work Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 9 Sep 2004 04:44:48
In Reply to: weird 2 stage fan problems after coolant flush....help!, Chet, Wed, 8 Sep 2004 21:34:51 Members do not see ads below this line. - Help Keep This Site Online - Signup |
In '93, the radiator fan was still controlled by the fan switch. So the reading on the temp gauge is only loosely related to when the fans come on. The temp gauge is coolant temp in the engine; radiator fans come on when the radiator is hot. Yes, you'd like to think they're the same, but they're not.
A sticky thermostat will cause the engine to run hot, and the radiator fan not to come on. The thermostat allows hot coolant to reach the radiator. The fans only come on if the radiator can't dump the heat out fast enough - usually if you're not moving. If the radiator is dumping heat fast enough to stay below the fan switch temp, it's doing its job. It's up to the thermostat to regulate engine temp.
First, I'll bet you came on at low speed first. I can say that, because if the fan tries to go from off to high speed, the additional current pull tends to pop the 30 amp fuse. It has to start low first, then switch to high.
As to having the radiator fan come on high sooner - again, the fan only removes heat from the radiator. If the thermostat isn't letting hot coolant out to the radiator, a lower fan switch temp won't help. If the radiator isn't dumping heat well enough because it's clogged, blowing more air is just a stopgap. When driving along, you get lots of airflow - if you still need a fan at high speed, something is wrong with the radiator.
My guess - you've still got some air trapped in the system. No big deal - the system is self-bleeding, assuming that the thermostat was installed correctly (little hole up). It can just take a while. Also, engine temp is controlled by the thermostat, and I've seen them do funny things when new or with new coolant. If the problem persists after a few hours of driving, then I'd dig deeper.
Yes, there are ways to get the fan turn even sooner - but you've already done that.
posted by 192.249....
, Thu, 9 Sep 2004 04:44:48 <-- Viewing This Message
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