What do you mean by coolant mode? Were you overheating?
Could be water pump going bad.
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Found this Googling around. You should really have a scan tool
Hello, the cooling fan is designed to come on when and if the temperature exceeds 223 degrees or if the AC freon pressure exceeds 190 psi. So, you were on the right track but did not let the temp get high enough to activate the cooling fan. If the temp exceeds 230 degrees or the pressure exceeds 240 psi, then the high speed fan comes on. Normally in the second condition the engine light will also come on and set a DTC code so the system can have diagnostics run on it. Because the fans are controlled by the PCM (power train control module) and they are a class 2 electronic device, the proper way to test them is with a class 2 scan tool so the relays and temperature sensors can all be tested together. That way if there is a malfunction in the system, it will show up on the scan tool. About the only things that can be tested without the scan tool is the fan motors themselves, by simply installing a fused jumper wire to them one at a time. Thanks
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Last edited by dondiego; 05-23-2013 at 06:24 AM.