Function of the Heater Core Temperature Sensor 4th Gen

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

RamDiver

Senior Member
Joined
Jan 23, 2022
Posts
1,815
Reaction score
2,848
Location
Marlborough, Ontario, Canada
Ram Year
2021
Engine
Hemi 5.7
I do not understand a few things:

If the Thermostat is 185°F to 190°F, does that mean that the water in the hoses is the same temperature ?
If the water inside of the hoses does reach that temperature, where the hell does that heat disappear to after passing through 5 foot of hose ?
I can tell everyone, that the heat in my Ram, even when new, never came anywhere near that temperature, even with the Recirculation door closed.

Take a ride in a Ford truck that is 5 or more years old & you will not want to keep the heat turned up to full heat.

The same when it comes to the hottest part of the summer, our Rams do not really cool off the inside of the cab when the outside temperature is over 100 - 112°F plus

The temperature inside the hose better be close to the thermostat value, I'd guess within about 5° or 10° depending on the outside ambient but don't forget, we're measuring the temperature of the outside of the hose.

IIRC, I saw about 175°F where the hose goes through the firewall and into the heater core.
So maybe, the thermostat value less 15°?

I've read countless reports that describe poorly performing HVAC on Ram trucks, mine is not one of those.

It takes no effort to make it meat locker cold in the summer or blazing hot in the winter.
I have no idea why my Ram's HVAC is excellent and others are not.

.
 
OP
OP
C

CM_Ram13

Junior Member
Joined
Oct 15, 2023
Posts
23
Reaction score
8
Location
MA
Ram Year
2013
Do you have EATC? (Electronic Automatic Temperature Control)
This is the hvac control unit in my truck. I don’t believe there’s any EATC, only manual controls.
 

Attachments

  • IMG_7900.jpeg
    IMG_7900.jpeg
    49 KB · Views: 7

mtnrider

Senior Member
Joined
Sep 25, 2014
Posts
3,144
Reaction score
3,358
Location
Georgia
Ram Year
2016
Engine
6.7 Cummins
I do not understand a few things:

If the Thermostat is 185°F to 190°F, does that mean that the water in the hoses is the same temperature ?
If the water inside of the hoses does reach that temperature, where the hell does that heat disappear to after passing through 5 foot of hose ?

That rubber hose is a pretty good insulator.... The water itself is going to be in the 180-190 range.
 

Sherman Bird

Senior Member
Joined
Jun 28, 2019
Posts
1,482
Reaction score
2,168
Location
Houston, Texas
Ram Year
1998
Engine
5.2
So, I went into my service information. The manual HVAC is all they show for the 2013.
That said, there is no heater core temperature sensor shown, BUT, there is an evaporator core temperature sensor shown.
 

GTyankee

Senior Member
Supporting Member
Military
Joined
Nov 2, 2020
Posts
9,925
Reaction score
12,352
Location
El Cajon Calif. 92021
Ram Year
2016
Engine
3.0 ecodiesel
What is my HVAC system called

I only use the RECIRCULATION button in the image
everything is else i do on the radio screen
I don't even change the vents settings,
I just have 2 vents open on the dash, the ones on the passenger side are closed. No sits there, so i just closed them.

1698889565013.png
 
Last edited:

Dusty

Senior Member
Joined
Jun 6, 2013
Posts
1,190
Reaction score
1,223
Location
Rochester, New York
Ram Year
2019
Engine
5.7 Hemi
The temperature inside the hose better be close to the thermostat value, I'd guess within about 5° or 10° depending on the outside ambient but don't forget, we're measuring the temperature of the outside of the hose.

IIRC, I saw about 175°F where the hose goes through the firewall and into the heater core.
So maybe, the thermostat value less 15°?

I've read countless reports that describe poorly performing HVAC on Ram trucks, mine is not one of those.

It takes no effort to make it meat locker cold in the summer or blazing hot in the winter.
I have no idea why my Ram's HVAC is excellent and others are not.

.
There were complaints about HVAC issues soon after the 5th gens were released. They were not meeting the design specification. Ram issued a retrofit that essentially replaced the entire Heater/HVAC assembly (plus a software update). I've got a very early 2019 and mine has always met the factory specs. Quite by accident i think I may have stumbled on the root cause of the problem.

As far as heat issues go, I can't think of any complaints I've heard except this OP's.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 10109 miles.
 

RamDiver

Senior Member
Joined
Jan 23, 2022
Posts
1,815
Reaction score
2,848
Location
Marlborough, Ontario, Canada
Ram Year
2021
Engine
Hemi 5.7
There were complaints about HVAC issues soon after the 5th gens were released. They were not meeting the design specification. Ram issued a retrofit that essentially replaced the entire Heater/HVAC assembly (plus a software update). I've got a very early 2019 and mine has always met the factory specs. Quite by accident i think I may have stumbled on the root cause of the problem.

As far as heat issues go, I can't think of any complaints I've heard except this OP's.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 10109 miles.

That may explain why I thought there were HVAC issues but in reality, they were limited to a certain vintage of 5th gen trucks.

I've dealt with many poor cooling faults and I think they include 4 gen as well.

.
 
OP
OP
C

CM_Ram13

Junior Member
Joined
Oct 15, 2023
Posts
23
Reaction score
8
Location
MA
Ram Year
2013
I’m thinking it’s mostly something running through the coolant system that sometimes blocks the core. I was driving on the highway yesterday going about 80mph for half an hour with heat on - got inside air temp to 80°, still not hot but at least warm. Driving 50mph maybe 5 minutes, inside air temp 71°. Shut the truck off and got out for half an hour, then got back on the highway up to 90mph for 10 minutes, heat at 96° - actually HOT, had to open the window a bit. Then cooled again as I slowed and down to 70° on backroads. I didn’t change the hvac settings at all: fan speed on 2nd of 4 speed, full heat, blowing on face. Drive for approximately 2 hours total. Outside temp 35-38°.

Doesn’t always do that but seemed odd the higher the speed/rpm, the hotter the air temp out of the vents. Any different opinions with that info? I’m still going to change thermostat, water pump, core and fully flush everything this weekend.

All cold this morning - outside temp 21°, inside air blowing 52° on full heat.
 
Top