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Discussion Starter · #1 ·
Have this intermittent code on my 2006 Maxx LT, 3500 6 cyl "Coolant temperature below thermostat regulating temperature"
Temp gauge reads halfway between the "C" and "H" marks on the gauge, and the heater will roast you after about 5 min on low blower speed. What would I need to be checking? I would think, if the thermostat was having problems it would affect the heater operation.
 

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I had an Astro van that had a thermostat that was not opening at its 195F setting and it set the low coolant temp. code. It was opening too soon.
Heat was OK until outside temps. got down in the low numbers and then hot went to warm.
Also, engine not up to full operating temp. will use more gas also.
Contactless temp. gun is the only way to verify if it's the thermostat or the sensor.
 

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You can us a meat thermometer. Full heat, low fan speed, driving for 30 minutes the air temp at foot level duct should be above 180F if the engine has a 195F thermostat. If it has a 180F stat, then duct temp should be above 165F.
 

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There is a chance the coolant sensor is suffering from a type of electrolysis.....that has gum,Ed it up and not allowing for correct readings.. I would change it...... not the Guage one.... the ecm one.....not sure which is which for sure..... butI think the one on the motor is for ecm and the one on the rad is for the Guage ( A TOTAL GUESS THOUGH ...so confirm)
 

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Discussion Starter · #5 ·
There is a chance the coolant sensor is suffering from a type of electrolysis.....that has gum,Ed it up and not allowing for correct readings.. I would change it...... not the Guage one.... the ecm one.....not sure which is which for sure..... butI think the one on the motor is for ecm and the one on the rad is for the Guage ( A TOTAL GUESS THOUGH ...so confirm)
I will look at that, the coolant is fresh looking Dex-Cool, so it may have been changed at some point by previous owner
 

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I will look at that, the coolant is fresh looking Dex-Cool, so it may have been changed at some point by previous owner
Usually you can find coolant testers that will let you get a more accurate assessment of the coolant's condition than you can by just looking at it.
 

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Discussion Starter · #7 ·
I'm gonna go and get a thermostat for it, from the phots I saw of the thermostats, they have the seal already on them. So do I buy an additional seal, for the thermostat housing?
You can us a meat thermometer. Full heat, low fan speed, driving for 30 minutes the air temp at foot level duct should be above 180F if the engine has a 195F thermostat. If it has a 180F stat, then duct temp should be above 165F.
I put a thermometer in the foot duct, with blower on low and on full heat. I left it in there for my entire newspaper delivery route, which lasts about 90 minutes. Thermometer read just over 150 degrees
 
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