Not sure but bypass in heater core might be relaying fluid back out. I know if core gets clogged there is a bypass. Man I feel for you. Might need to go get a coolant flush and ask technician to check it out. Or go to auto parts store they are knowledgeable about lots of stuff. GL

 

Not an uncommon problem if one lives in a super warm climate--the heater never gets used during the summer, and at the first hint of cold weather--ooops! Sometimes a flush works, but I had to replace the entire heater core in a chevy I once owned--kind of made be a convert to flush the cooling system regularly.

 

I'm having same issue! Have u flushed coolant? Have you fixed the issue? If so how

 

My local independent tire guy does most of my maintenance chores--I'm getting too old to be crawling around on a cold floor under a car... I figure that with all the money I've saved over the past 60 years being a DIYer (I've built my own house and airplane...) that I can now afford to pay someone else--it hurts, especially when you know that you know more than the mechanic...

 

I perused my 2014 Factory Service manual, which may or may not be exactly the same as your 2012.

The fact that both the inlet and the outlet hoses to the heater core are hot seems to indicate that you have coolant flow to the heater core...correct??

The service manual lists these "mechanical" problems for insufficient heat (with good heater core coolant flow):

•Obstructed cowl air intake
•Obstructed heater system outlets
•Inoperative engine thermostat
•Inoperative blower motor system
•Inoperative A/C-heater control
•Inoperative blend door actuator
•Inoperative, obstructed or improperly installed blend-air door

The main blend door changes the system between AC and heat. If stuck in the up position, the air flow will NOT pass over the heater core. There are other "doors" that change the air flow between defrost,foot, dashboard, etc..

The AC/heater temperature control knob moves the blend door actuator. If the blend door/actuator does not operate correctly, A DIAGNOSTIC TROUBLE CODE should be thrown.

There is one fuse (#22) labeled heater, but I am not sure what it controls.

I cannot find anything about any relays....yet. UPDATE - the only heater relay info I found (so Far) is for the diesel engine version only

 

Good stuff. I will look into the doors Friday see if I can't find the blockage. Any manual that shows me how to get to them? Winter is almost here. Heat is a must for the wife and kids. Thank you

 

Update 1. Heat somewhat works when I recycle the air in the cabin. Shut it off and it's cold. But it's much warmer when on. Not sure what that means

 

Final update. Door blend actuator was broken. Found it not moving when switching from cold to hot. Manually moving hot works great. New part 26$.

 

Great news! Just how much did you have to disassemble to find this part, and where did you buy it?

 

Jack, I cannot find any good pictures of the blend door actuator (motor unit) where it attaches.

It is very easily diy serviceable. You can see it if you look below and right of the steering wheel, up under the dashboard. It is mounted on the outside of the entire HVAC unit. You unplug the wire harness, remove a couple of screws, and it simply comes off.

Google Jeep Patriot Blend Door Actuator and you will see it available at any auto parts supplier for under $30: http://www.autozone.com/1/categories/jeep-patriot-limited-heater-blend-door-actuators

Here's what it looks like from a Dodge Avenger thread: http://dodgeforum.com/forum/2008-current-dodge-avenger/382927-2012-avenger-blend-door-actuator.html

 

My question, how do you set up the arm when putting back in the new unit ???

Be Safe JIM

 

OK got it fixed. My arm had come out that was confusing me. Once I put the arm in place, plunged the unit in, hanging, turn on the car, set the cold hot to middle, turn off the car and just push it in. Works like a charm and for 27.00 a steal !!!

Thanks for the info, Be Safe JIM

 

Pm'd you. Sorry for late reply. Glad it's fixed. Supposedly, you just turn the motor output by hand until it lines up with the actuator linkage.

The FSM states that you have to calibrate the new motor using a scan tool, but you guys don't mention doing this.

 

Im having similar, but with other symptoms, as well. 2012 Jeep Patriot Limited 2WD.
Heater will often suddenly start blowing cold air... after a few minutes, heat will return. Also, the temp gauge used to always sit between the 1/4 and 1/2 marks. But now it sits right at the 1/2 mark, and will occasionally creep over. Adding to this, in the last couple of days, the temp gauge will often just sit at the far left when started, even when heat is coming out of the vents. But then, after I stop, then accelerate, it will suddenly go to that 1/2 point on the guage.
I took it to Pep Boys, who did a cooling system check. They ran it for 2 hours straight, and did see the temp gauge at 1/2 point, but it never did technically overheat.

 

Hey Timonator,

I am sorry to hear about your recent experience with your Patriot. Is this the first time your vehicle has exhibited this behavior?

 

Sorry to bring back such an old thread, however, I am having similar heating issues and think it is the blend door actuator. Once the actuator is removed, can the door be operated manually? If so, can it be spun by hand or do you need something like a screw driver?

Thanks in advance.
Mike

 

Last Tuesday morning it was cold and rainy here so I turned the heat on but only cold air. WTF?

After spending the following 2 days reading tons of posts regarding this issue, I learned many things and was able to narrow the checklist to a few items: clogged heat core? nope, because both hoses were hot. Coolant level was OK. Issues with blower motor? No because air was flowing. Fuses? nope. Could it be a bad blend door? YES!

As you may already know, few minutes after shutting off the vehicle you can hear a mechanism behind the dash making a 'robotic' noise. That is the A/C doors actuators moving. Sound from the left (behind steering wheel) is the Blend-air Door which controls Cold/Hot air. Sound from the right (glove box side) that is the Mode Door, which controls air flow from center, floor and windshield vents.

Long story short what I did was to manually (and carefully) move the blend door actuator arm and the white gear which for some reason suddenly got stuck. Immediately when turning temp knob the actuator started to move. Heat again!

My suggestion is to periodically check if both actuators are moving. No closing sound after shutting off the vehicle could mean problems with actuators. It seems a little of white lithium grease now and then should do the trick to avoid this condition.

This forum saved me again. I hope this help others too.
Thank you all.

 

I'm having a problem with the heater in my 2014 Patriot North Edition. I recently dropped it off at the dealer to have work on replacing an OCR sensor. After I got it back, the heater only blows cold air. I confronted the service manager who denied that they had anything to do with the heater failure. The heater blows cold air through all the vents when the temperature knob is set to hot. If the heater core had failed, would there be any sign of coolant leak on the cab floor? Where would I find the relay for the heater? After the jeep is turned off, there is a mechanical sound coming from behind the glove box, so I assume that the blend doors are functioning. Winter comes early to this part of the world. I won't be bringing it back to the dealer ever again. Need help. thanks in advance.

 

Hi EagleNova,

To discard a heater core failure, do the following: after running the engine for some time (temp gauge needle near midpoint), open the hood and look for 2 black hoses located exactly behind the engine's upper right corner going through the firewall. Carefully touch both hoses. If they feel hot, that definitely is not a problem related to the heater core.

The mechanical sound you hear (glove box side) comes from the mode door actuator, which controls air flow from vents. Nothing to do with hot/cold air. If no mechanical sound from behind the steering wheel side, you probably have a bad blend-air door.

Turn ignition on and take a look below the steering wheel (upwards to gas pedal) and search for a black motor unit with a white arm and a big white gear. That's the blend-air door actuator. Now, turn on the A/C and move the temp knob. If the mechanism doesn't move while you change temp, it has stuck on 'cold' position. Gently move the arm and/or gear to free it.

You should now have hot air again and A/C should react to temp changes from the knob.

 

Hi EagleNova,

To discard a heater core failure, do the following: after running the engine for some time (temp gauge needle near midpoint), open the hood and look for 2 black hoses located exactly behind the engine's upper right corner going through the firewall. Carefully touch both hoses. If they feel hot, that definitely is not a problem related to the heater core.

The mechanical sound you hear (glove box side) comes from the mode door actuator, which controls air flow from vents. Nothing to do with hot/cold air. If no mechanical sound from behind the steering wheel side, you probably have a bad blend-air door.

Turn ignition on and take a look below the steering wheel (upwards to gas pedal) and search for a black motor unit with a white arm and a big white gear. That's the blend-air door actuator. Now, turn on the A/C and move the temp knob. If the mechanism doesn't move while you change temp, it has stuck on 'cold' position. Gently move the arm and/or gear to free it.

You should now have hot air again and A/C should react to temp changes from the knob.

Excellent! I was experiencing the same problem and this fixed it! Can't imagine how much it would have cost to have this diagnosed.... Thank you!

 

Yeah, thanks