[Cciman]

Why worry about the temp of the heater air? You've got a good heating system.
Don't turn it up so high. Is this a real problem?

What are you trying to troubleshoot elsewhere in the cooling system?

Heater core flow is on the hot side of the thermostat-- independent of the thermostat and beyond. If you run both heater cores, full blast with cold cabin air, no load on the engine, you may bypass the cooling system (radiator) completely, as you don't reach temp to open the thermostat.

I don't trust your reading. I think you need a meat thermometer in the vent for accurate readings. Try that to confirm what you think the temp is.

 

[bennybigb]

I am going to try the meat thermometer in the vent and compare it to my heat gun numbers.

I'm just trying to not blow up the motor. I don't trust the factory gauges anymore since losing my Tacoma engine under very similar circumstances.

I really appreciate all the help! The Y hose reading and meat thermometer will hopefully show my van is operating correctly. Fingers crossed.

 

[LPete]

Try grabbing hold of the heater hoses with the engine warmed up. They should feel evenly hot, and you shouldn’t be able to hold onto them, since they should be 190 degrees or so. If they’re not evenly hot, you have some kind of flow problem through the heater core.

 

[bennybigb]

Made progress today, the Meat Thermometer is showing the infrared Heat Gun is not accurate. I did not test my van yet, but I did compare readings on our Camry and readings on my mom's 2008 Dodge Caravan with the 3.8. On my mom's 08 Caravan, the Heat gun showed 215 while the meat thermometer showed 160. I'm guessing my 2010 van will show 170 out of the vent with the meat thermometer, but I still need to verify this. I took some additional readings from under the hood of my mom's 2008 Dodge to compare to my van. My moms van showed 200 at the top of the motor and her radiator hoses were 180 Top, 120 Bottom.

So, I'm confident my vent temp is not actually 240 degrees! I do think my vent temps are hotter than my mom's and top of the motor temp has proven to be 10 degrees hotter than my mom's, so I fell like I still have an issue, but not as big of an issue I originally thought. Whoever first said an infrared temp gun struggles to get vent temps was spot on! I will continue to troubleshoot to see if I can get my head temp and vent temps down to my mom's temp range. Maybe 10 degrees is an acceptable variance?

Thanks for the input, help and ideas everyone!

 

[Cciman]

HVAC guys don't use heat guns for vent temps. I don't know how you are getting 240 with the gun.. Glad you are relieved 😌

Try pointing the gun at a known temp like ice water in a black mug, or boiling water in a dark pan.

 

[Jeepman]

HVAC guys don't use heat guns for vent temps. I don't know how you are getting 240 with the gun.. Glad you are relieved 😌

Try pointing the gun at a known temp like ice water in a black mug, or boiling water in a dark pan.

Just point it at the thermostat on your kitchen wall.

 

[KOG]

Your heat gun is BS.

 

[Rydgomez]

Don’t use a heat gun to measure temps at the vents.

 

[Cciman]

Those mechanical stalk thermometers can be off too. That small hex bolt at the top of the spike behind the bezel is for calibrating the display needle to ice water (or boiling at sea level).

 

[damianremodeling]

Hello Everyone, first time poster, long time reader.

My 2010 3.8L Town and Country with 116,000 miles has me confused. The Heat coming out of the vents gets up to 240 degrees on full heat! The temp gauge never goes over halfway, but if the heat coming out of my vents is 240 degrees, doesn't the motor temperature have to be 240 degrees also?

A couple more facts, I believe the thermostat works, because my top radiator hose is measuring 175 degrees. I would like there to be more pressure on the top hose though, is seems pretty limp when the car is running, I thought these things were supposed to have some pressure while the cooling system is hot.... The thermostat housing measures about 190 degrees and the top of the engine right next to the thermostat housing measures about 215 degrees (when measured by a temperature gun) The engine has been smelling slightly hot, but not too bad. I recently did a coolant spill and fill. I put in the correct G05 antifreeze and I used an air lift system to burp the air out of the system while both the front and rear heaters were on.

I don't know what the next step is, 240 degree heat seems way too high even though the rest of my gauges seem in range.

Do you guys have any ideas? What temperatures do you guys have with your heating system?

Thanks!

Ben B.

Don't drive it at 240F

1. Change thermostat - 195F. Plenty of videos how to on YouTube. And its 20 bucks.
2 . Burp, bleed air with a funnel with radiator attachment. - also 20 $ on Amazon and plenty of videos.
3 change cap - hose should be very stiff and hard under normal operation.
4 Check internal sensor temperature against gun temperature.
10-20-30$ max wireless ( Bluetooth) OBD "scanners" on Amazon - no need to spend more + the free Torque Pro app and you have a perfect " phone" OBD scanner , code eraser / lookup.
5. When all changed and closed up you should see thermostat fully open at 195F and top radiator hose getting warm ( even a bit before)
6 Run parked for a while - at 220- 225 max you should see radiator fan blowing on high.
And hose getting stiff

If that is not happening - mayyy be a bad water pump , but you would see other signs of that. Noise, leak, drip.

If you suspect " clogged" radiator it's easy to check - but unlikely unless your previous coolant looked like oatmeal or you used one of these " seal a hole" liquids from auto stores.

 

[Cciman]

did you read the rest of the posts? Try skimming.

 

[bennybigb]

Update. I was able to put some miles on the van while monitoring the vent temps with a heat thermometer, and according to the meat thermometer, the vent temps are 165-170. I will take it! My mom's 2008 caravan had vent temps of 160, so I am a little warmer than the 2008, but no where near the 220 my infrared heat gun registered. The Heat Gun did show my top radiator hose was 190, the bottom hose was I think 90. The top of my head, next to the thermostat measured about 205-210 degrees, which is a little warmer that what I would like to see, but it's probably fine. The Temp gauge registers right in the middle. I think the van still smells a little hot, but maybe it's just some fluids on the exhaust. Either way, I am not scared to drive it now, I don't think it's overheating. Thanks for the help everyone!!!

 

[Oscarphone]

You are using a heat gun? The approved way that I am aware of is a quick read thermometer stuck in the main vent (not touching any surrounding plastics/ducting). The gun is great for hoses or tires or components but not air. You may be measuring accumulated heat on a ducting surface.

 

[Cciman]

You are using a heat gun? The approved way that I am aware of is a quick read thermometer stuck in the main vent (not touching any surrounding plastics/ducting). The gun is great for hoses or tires or components but not air. You may be measuring accumulated heat on a ducting surface.

The temp guns are great for certain things, but only accurate if directed towards matte, or rough/dirty surfaces - at close distances. Any bright or reflective surfaces, or clear - it will give erroneous numbers -- certainly won't read air, liquid, or gas temp-- only off the closest surfaces. Does not work well on glass or most shiny metal surfaces.

240 F still seems strange reading off a temp gun. Tends to read low not high.