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What is temp of heater air?


James Morse

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Does anyone know what the spec is for the temp of heater air on full heat? Or has anyone measured a working system so they could tell me how hot it was?
 


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Uncle Gump

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That number will be dependent on engine temp... so really no hard answer to the question.

Can't say I've ever took a temp reading. I do know the a properly working heating system in a Ranger should cook you out of the cab.

Are you having heating troubles?
 

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I never measured it. If you're running a 190 degree thermostat or thereabouts, then the coolant going to the heater core should never be hotter than that. Plus, it will lose a little bit of heat getting there. Transfer in the heater core is probably not 100%, so there is some more loss. My gut feeling guess is that under optimal conditions, the air coming out of the vents could be anywhere around 150 - 170 degrees. Maybe less.
 

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The heater core after engine warm up should be about 160degF, coolant is 190degF
If outside air is 60degF then you should get about 140deg air coming out with fan on high

Problem is often Blend Door issues on 1995 and up Rangers
The Blend Door is electric and controlled by the TEMP knob on the dash
It directs the air from the fan either thru the heater core(HOT) or around it(COLD), or anywhere in between
If blend door is not directing ALL air thru heater core in HOT position then air temp will be mix with cooler air, so lower


Other issue is clogged heater cores, low flow of coolant so not getting very hot
After engine is warmed up feel BOTH heater hoses at the firewall, BOTH should be HOT
If one is much cooler then low flow
After engine cools down remove both hoses and use a garden hose to Flush the heater core in BOTH directions
This can sometimes clean it out
Whole Dash must be pulled back/out to change heater core


There is also a Heater By-Pass valve in engine bay, this should only be in use with MAX AC selected on dash
It is vacuum operated and I have seen people hook it up to engine vacuum directly, so NO HEAT in cab all the time
If this was done then BOTH heater hoses would be cool in above test
This valve should have a GREY vacuum line connected that runs over to passenger side firewall and into the cab
And if both heater hoses are cool then the By-Pass valve may be bad, stuck in closed position
 
Last edited:

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A bit of info from a sidebar conversation we'd had before the thread was posted:

Both heater hoses are hot as they go into the firewall
When moving the temp knob on the dash, you can hear the actuator moving from one limit to the other.

My vote is definitely on a broken blend door.
 

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Does the air temperature change when temp knob is changed, if not then yes blend door is not actually moving

Its not a small change from COLD to HOT, very easy to tell if its working
 

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The air from my heater blows at exactly "good and hot" kelvin.
 

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lol Dirtman

Thanks everyone, yes RonD the temp changes, on cold you get just fresh air (assuming dash vents used here), with a/c you get very cold a/c, and with heat all the way on, you hear "something moving" so at this point I'm suspecting broken or stuck blend door, or heater core not flowing nice. Yes both hoses are hot to/from the core. I had not flushed it (core) at the time I changed the coolant and put in a thermostat (it had no thermostat in it) so I kind of short-cutted the total procedure in the interest of getting the main part of it done. And I shouldn't have done that, but, messing with the heater core now (flush, and reverse the hoses) wouldn't lose me much coolant at all, I'd think.
 

fastpakr

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Turn off the a/c completely. If you put the temp knob on one end of the range and put your hand in front of the vent, do you feel the temp change as you rotate the knob slowly?
 

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If the vents change position properly (from defrost, to floor, to forward) then the vacuum system is fine. If it blows nice cold air then the AC is obviously fine, if BOTH heater core lined are hot then at least some flow is going through the core. So with that info yea I'd just toss a new blend door motor in it. They are fairly cheap (like $20-30 bucks). The first time you change one you will curse at it but after you figure out the proper contortion and how to dislocate your fingers they only take 5 minutes to swap out. Drop the glove box door completely down, get the tiniest thinnest ratchet in existence with a (7mm?) Stubby socket and remove the 3 screws. I found this thingy on Amazon a while ago and realized it's great for this job. You need a hex head bit driver socket for it but you can also get those on Amazon.


Love this dang little ratchet for interior fixins...
 

James Morse

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yes fastpakr it does change, from ambient outside (67 when I tried it) to about 100F and if you are in the middle then it is about partway between them, so, yes, it changes. I should be getting hotter air than that, I'm running 190-195F thermostat. It should be hot as heck. Still suspect mix door, if not that, heater core. Haven't had a chance to do anything more with it, I'm thinking, flush the heater core well in both directions then try it again and see if it makes any difference at all. That's non-invasive. If it doesn't make any change at all, then, either the heater core was ok to begin with (or totally fubar, but I doubt that since both hoses get hot, so water is going through it), and it's back to the blender door stuck, broken, or the drive to it messed up somehow. I'm pretty sure the actuator is doing its thing.

I actually have a couple of those ratcheting screwdrivers, in regular and phillips. Also a bit driver. They're sometimes indispensable.
 

fastpakr

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Hmm...

Knowing that it absolutely does change (and pretty significantly), and that there aren't any crazy clicking/sticking/ratcheting noises from the blend door area makes me think that it is in fact working properly.

I'm changing my vote to restricted heater core and hoping that a good flush helps significantly.
 

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With fan on HIGH and TEMP knob on HOT
Engine idling
You should be able to feel which Hose is IN(from engine) and which one is OUT(of core)
The OUT hose temp will start to go down a bit, because HEAT is being TRANSFERRED to the air
If both hoses feel the same then very little heat is being transferred to the air, so............clogged core usually, could be blend door not sending all air from fan through the core

If you do have even a slightly cooler hose then that's the one you want to hook garden hose up to FIRST, to reverse flush the core

Just a heads up about heater cores
They can clog up but still have OK flow so both hoses get hot, but only part of the core is actually heating up so it doesn't heat up the air as much
Radiators do the same thing but you can run your hand over radiator and feel the cool spots where it's clogged up, can't do that on heater core

If flushing core pull the hoses off at the By-Pass valve, makes flushing easier
Run the garden hose water in both directions first
Then Blow into one hose to clean out as much water as possible
Get some CLR or Vinegar
Mix it with HOT water, pour it into the core
Wait 15-20min then flush again
Repeat as you see fit
 

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Or leaves, dog hair, mouse nest, etc. restricting airflow through it.
 

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Using a pocket Thermometer clipped into the center dash vent, after warming up,
cab heat on max runs >130f in my 2001 V6~4.0L~SOHC with a 183f CoolantThermoStat,
cab heat on max runs >140f in my 2008 V6~3.5L~DOHC with a 170f CoolantThermoStat.
Cold start to warmed up idling is 5~10min on both vehicles, quicker when driving.
 


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