2001 Ranger 2.3L L4 no heat
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2001 Ranger 2.3L L4 no heat
Phase 2 of my troubleshoot. Originally, my coolant temp gauge pegged out to cold as far as it could go. Thought the temp sender went bad as I see no engine warning light (which works on key on, no start). The gauge circuit apparently has no input to the PCM and henceforth, has nothing to do with my problem. Not jumping to conclusions, I left it go. I recently found I have no heat. Now if I understand correctly, the Cylinder Head Temp sensor controls the electronic thermostat through the PCM. According to what I read, the CHT sensor is actually 2 thermistors, 2 different circuits. I assume that the thermostat is controlled by a linear voltage. Anyone know what voltage the thermostat operates between so I can test it without removing it? I'm not much of one to take things out I don't need to. Maybe even a clue what resistance values the CHT runs at nominally?
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Hook a scanner up to the obd2 port it will tell you what the engine temp is. If it is really running cold it should turn on a cel for low engine temp.. if this is a 2.3 Dohc engine the the temp sensor for the gauge is on the back of the head. And there is know way to get to it short of dropping the tranny. And yes the thermostat is electric setting on cold side of the radiator. (what engineer had this brain fart) that being said these do have hot water valves on them controlled by vacuum. And there is always the blend door issue.
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I posted earlier and you answered some questions. Originally, I thought the gauge or sender went bad. Checked the gauge by using a variable pot. Can't get my hand down to the sender to even unplug the sender and lie to it. That said, I found an interesting article and explanation as to how this particular year 2.3L L4 doesn't use the sender for anything other than the gauge which makes sense because there is no input from it to the PCM. The article says the Cylinder Head Temp sensor tells the thermostat when to and how far to open the thermostat. The system uses a fail safe. If the head temp rises too high, it opens the thermostat all the way. This appears to be what's happening and leads me to believe the CHT is bad or the thermostat is stuck. I'm not one to throw parts at something especially a 130 dollar tstat not to mention dropping the tranny. I was going to braze another fitting in the coolant tube and put the sender there but all this new info has me wondering. The engine never overheated as I would have known. I've never had such a time diagnosing a coolant issue. That's why I asked if anyone knew what voltages the tstat operates at from closed to opened. I could at least figure out which way to go.
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