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Re: Cooling fan question... Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Sun, 27 Mar 2005 17:36:28
In Reply to: Cooling fan question..., Justin, Sun, 27 Mar 2005 16:18:44 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'm pretty sure the '93 still has the thermoswitch in the radiator. The thing to remember is that the thermoswitch in the radiator that controls the fans comes on and goes off depending on the Radiator temperature. The temp gauge on the dash is the coolant temperature at the engine. The two aren't the same.
Assuming a stock radiator thermoswitch, low speed comes on at 90C, and high speed at 106C. Notice that the thermoswitch on on the far side of the radiator from the inlet.
Normally, while driving along at speed, you've got lots of air blowing over the radiator. The hot coolant from the engine flows into the radiator, where it gives up heat to that nice airflow, and the cool coolant flows back into the engine. The thermostat controls the flow, opening up around 89C (stock). If you lose airflow over the radiator, usually because you're not moving (sitting at idle at a light), the radiator heats up. But the coolant in the engine heats up more. So not until the coolant in the radiator has reached 90C does the fan come on - the engine is probably quite a bit hotter.
So, when stopped in traffic, it's normal for the temp gauge to move up; 10:00 isn't unusual. The fan comes on, and cools the coolant in the radiator. That will drop the temp, and it'll flow into the engine. And the engine temp will drop. But the fan cuts off when the radiator cools off. So the engine temp doesn't drop all the way down. It should when you get back up to speed.
The high speed kicks in if the temp keeps climbing, because the low speed isn't pushing enough air. Typical for that would be a very hot day, when the air you're blowing over the radiator isn't very cool, and the engine heat load is big (like the AC on). It may also kick in if the AC pressure exceeds a certain level.
Many folks put in a cooler fan thermoswitch - one that kicks in at 82C, instead of 89. But again, the temp gauge is the coolant in the engine, and the thermoswitch goes by radiator temp. And at idle, the water pump isn't going that fast, so there are temperature gradients.
posted by 12.76.132...
, Sun, 27 Mar 2005 17:36:28 <-- Viewing This Message, Mon, 28 Mar 2005 05:27:07
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