Is it OK to bypass the heater core?

"Air flow is fine. Air movement from floor to dashboard to defrost works fine. but filed to say air flow hot works. just air." I can not guess this so will do it all.
it is just a liquid to air heat exchanger. (tech, pure)\
to get hot wire the hot core blend door must be fully open.
that is goal 1. we just watch the drive motor actuator to do that.

blower is good. .
heat comes from the engine
so we scan the PCM for PID ECT temps readings/
180f to 200f + any real scan tool can do this. easy.
150f is STAT stuck open or missing and BAD for sure. (bingo)"?

if lower the thermostat 20 year old is bad and for sure that old. yah
or using IR thermal gun a $15 tool the thermostat housing shows up near 180f+ good, 150 no.
then I check both cab heater core hoses,_ tubes.(at fire wall)
the are both hot,. 180f+ if yes good or one is way low that means the core is blocked.(even hand touched hand flies off test is GOOD.)
ok core is hot, we not go to CAB side.

hot air fails:hard. (i guess, ?)
that means the damper door is closed, on the heater core.
some cars have left and right dampers, (jeep commander does)


if a blend door jams ,as seen by eyeballs does not move or limited range we remove the motor there and turn the door hinge shaft by hand end to end to prove it does not jam. end to end.
ok door is free as a bird.
if ok the the motor actuator is bad (or weak) oem parts work better.
same goes for all doors, mode./blend/ or recirc/fresh failing
and some have left and right blend.
and sure VENTS, if some vents work not say so

AC is a whole other story ,,not doing both now me.

A heater core is a component inside the HVAC box (located under the dash) that is heated by engine coolant. Vent temperature is increased by routing air through the heater core before it comes out of the vents. The temperature requested by the HVAC control module determines how much air passes through the heater core and how much air bypasses it. This event is called air "mixing" or "blending" which refers to the hot air and cold air ratio. Air routing through and/or bypassing the heater core is carried out by the use of a blend door and blend door actuator. Over time these two components can fail mechanically which often results in abnormal noises and improper positioning leading to undesired temperatures. Now, higher-end A/C systems with dual-zone climate control have multiple blend doors and actuators; this is how how the two different temperature "zones" are achieved. A failure with only one of the zone's blend door/actuator would result in desired temperature out of one zone's vents and abnormal temperature out of the other zone's vents. You can read more here: https://www.yourmechanic.com/article/what-is-the-difference-between-climate-control-and-air-conditioning

Bypass the rear heater core take both hoses off the core and go to hardware store ask for apex tubing an conect hoses to it n put 2 clamps on each side u will have to guess the size or cut a piece of it n take it with u to get the size tubing u need that will kill all heet to back not the front

The actuator door that is behind the dash that closes off the heater core from shooting hot air thru the vents might be your problem. When you turn on your ac the actuator shuts the door to prevent the air from flowing thru the heater core into the cabin, this may be your problem if everything else is working properly. Let us know.

I would talk to a dealer or two.
You could have a damaged heater box or blend door. The blend doors direct air thru the heater core and the vents.
There was a recall for some blend doors on some Jeep models.
You may have to contact factory customer service to get it fixed.

Hi, Is both hoses hot going in and coming out of heater core,if not heater core is stopped up. If both hoses are hot. check the blend door motor and door its self to make sure its not broken. if i can further assist you just re post. Thanks dodge tec

if line out is not geting hot then the core must be clogged

heater core is going bad my dodge ram truck did the same thing for about three months then steam startedcoming out of the vents it was antifreeze i have not fixed it yet i just bypassed it for now cause its hot and i have to take the dash completly out to get to it, and yes my airconditioner was blowing out hot now immediatly after i bypassed it blows cold again.you have to find where it goes into the motor on both sides so follow the hoses from firewall then buy a 3ft hose to go from one side of motor to the other problem fixed! well that is you wont have a heater until you change the heater core

it has a valve on the heater hoses on one hose that has a vacuum line running to it check both sides of the hose on each side of the valve if its hot both sides its ok. Then check to see if both hoses are hot this will mean that the water is flowing ok if its not reverse the hoses on the heater core somehow it will flush the core out. If this is all working then its the door on you heater box not closing the air conditioning hole off . It goes through the same vents as heater

You have a leaking heater core. This can leak whether you are using the heater or not. Heater core replacement is pretty simple, except that in many cases you must remove the dashboard to gain access to the core. This can be a major undertaking.

What model year is your S-10?

Good Luck!