Poor heat

[Scotthw]

I got an 04 liberty and the heat isn't the best the faster the fan speed is the cooler it gets but If I put it on circulate cabin air it gets supper warm in there but as you know only comes out of the face vents so windows start to fog up but if i put it back to defrost it cools off again any ideas the heater core has been flushed and has good flow and vehicle sits right in the middle of the temp gauge
Thanks

 

[tommudd]

What else has been done ?
MOPAR thermostat??
Flush radiator
was the heater core professionally done or just a DIY ?
Little more info as to if it did work and then stopped or never did or ??

 

[Scotthw]

I bought it in the sumer time it was over heating found out the rad had a hole and was plugged with stop leak so put a new rad in and had the heater core professionally cleaned not sure on the thermostat but the temp stays right in the middle of the gauge

 

[tommudd]

Due to the way the heater cores are made they are very hard to flush well , even professionally
Then the very worst was some one using stop leak in the system which is a huge no no
as afr as the temp gauge its more of an idiot gauge then real accurate
Even sitting middle ways it can have a difference of 30-45 degrees
But I would start with the simply things like a new MOPAR thermostat and of course Hoat coolant

 

[Scotthw]

Ok thanks i did have the hoses off the heater core after they flushed it and thought the flow seemed pretty good i could blow threw it with not really building any pressure but ill change the thermostat and see what that does

 

[Big Al]

Scott,
What your describing is exactly what my heating system is doing.
Really hot like 145 F when I put it on recirculation. And like 104 F
when I put it on defrost.
Also, anything above setting #2 blows cool air.
I also took a infra red temperature gun to the 2 hoses on the firewall and seen that there is a drastic drop on the return hose so the back flushing I did on the heater core has helped. Supply hose 180 F and the return hose is like 150 F. I'm not sure if my next task of replacing the blend door is going to solve the problem, but it sounds like it may be the problem as I get really hot air in the recirculation mode. From what I read so far on the blend door, it fails in the cold air position. Also heard if you remove the glove box, you can see the electrical plug in on top of the HVAC unit where the blend door is located..
Also to change the blend door actuator, you need to remove the dash board. Sounds like a summer project for me.

 

[Scotthw]

So your saying its the actuator or the door its self? Cause mine in the warmer days were I had to turn the heat down it would actually get cooler as I turned the knob

 

[Big Al]

My cold and hot knob works well. Now is this what controls the blend door, I'm not sure.
All I know is on the recirculation mode, blows hot air like it should in all settings and once I move it from recirculation mode, all other modes it blows cool air and I never changed the far right knob setting from hot air.
Why does the air change from really hot on recirculation to cool air on all other setting is my mystery.

 

[Big Al]

I've read where the motor on the blend door fails to move and I've also read where the blend door breaks off the pivot shaft.

 

[Scotthw]

Ya mines honestly like the door isn't shutting all the way and letting outside air in but it must be shutting if it gets hot once I put it on circulate wonder if the control on the dash isn't working

 

[Big Al]

What I've read is the control knob to change from recirc to defrost is vaccum actuated off the intake manifold. The blend door is a electric stepper motor.
Reason I'm leaning on the blend door motor for my next process of elimination is it is widely talked about on here.

 

[ltd02]

Change the temp setting (doesn't matter what directional mode you are in) and listen for a slight buzz behind the center bezel where the switches are located and a bit toward the right side. Might help to remove the glovebox and listen there too. My working blend door actuator motor always made a bit of a buzz. When it failed it fail cold and no position setting would give any heat or cause a buzz. The OP problem sounds like bad coolant flow and/or a bad heater core to me. They're a bypass type core so they will flow around the core if restricted due to crud. Do what Tom suggested first.

Is the coolant level good and is the rad cap holding pressure?

 

[Scotthw]

Change the temp setting (doesn't matter what directional mode you are in) and listen for a slight buzz behind the center bezel where the switches are located and a bit toward the right side. Might help to remove the glovebox and listen there too. My working blend door actuator motor always made a bit of a buzz. When it failed it fail cold and no position setting would give any heat or cause a buzz. The OP problem sounds like bad coolant flow and/or a bad heater core to me. They're a bypass type core so they will flow around the core if restricted due to crud. Do what Tom suggested first.

Is the coolant level good and is the rad cap holding pressure?

Ok thanks that makes more sense now that you say its a by pass type heater core thanks

 

[Scotthw]

I just took it for a couple mile drive down the highway and took temp readings off the top rad hose and heater core lines and the hottest readings i could get is 130f on the top rad hose and 115f on the heater core lines does this sound normal or not

 

[ltd02]

Doubt a couple miles will get it to temp but could depend upon where you are. Sounds cool to me if it were fully up to temp. Mine used to run about 180 to almost 200 depending upon traffic and when fully up to temp. Never checked at the heater hoses.

 

[Scotthw]

I let it run for a half hour before I took it out

 

[ltd02]

Yeah that's pretty low. Is it cold where you are? If so it sounds like Tom may have nailed it with the tstat being bad.

 

[Scotthw]

I'm up in canada it is about 32f today

 

[ltd02]

Tstat may be stuck open. Sometimes you'll get a code for taking a long time to get up to temp but might not be quite that bad yet. On the good side, way better to run these things cold that to overheat it...

 

[tommudd]

From the sounds of things I'd blame it on the idiot who put stop leak in it
That stuff went clear through the system including heater core and blocked some vital things
But again replace the thermostat (ONLY MOPAR WORKS ) remove hoses see what they look like inside etc
Then try it
Next is the heater core , but like mentioned they have a bypass built in so water/air/ etc may come through but not circulating through the whole core
Hope it is not that but would not be the first one