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No heater operation - blend door actuator location?

Tiny
MIKE R1025
  • MEMBER
  • 2008 JEEP LIBERTY
  • 3.7L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
With the blower on and the thermostat set to cold and the vent blowing on your face it will blow cold air on you. As soon as I switch the thermostat to full hot, the air comes out of the defrost. It is a little warm but not enough to heat the vehicle. So basically no heat. What I have done so far: Replaced coolant and burped the system, replaced the thermostat, replaced the blend door but with same actuators, replaced control panel, flushed the heater core and heater core lines.
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Wednesday, November 1st, 2017 AT 1:05 PM

43 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Do the heater core hoses fell like they are the same temperatures. If so you do have circulation, they should be quite hot to touch, if this is so, it will be a problem with the blend doors not opening, check these and make sure you do have good circulation first.
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Thursday, November 2nd, 2017 AT 3:29 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
The hoses are warm to a little hot and the same temperature. The blend door is brand new. I think there is a vacuum actuator in the glove box. It says if this is bad or the line is leaking, it will default to defrost and that is what it is doing. Your thoughts?
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Thursday, November 2nd, 2017 AT 3:41 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Looking at Mitchell 1 it is a fully electric climate control system, a scan tool is required to check actuator operation and calibration, this can be function tested only in this model. I have been looking at a 2008 Jeep Liberty 3.7L engine Sport is this your model?
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Thursday, November 2nd, 2017 AT 4:06 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
This sounds like a programmatic error which could be caused by a shorted blend door actuator I know you said you replaced some of them can I ask which ones?

Below is a diagrams to help us get on the same page.

Please let us know. I am interested to see what it is.

Cheers, Ken
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Thursday, November 2nd, 2017 AT 5:42 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Hi Ken, I replaced the blend door that has two actuators on it that is located just above the accelerator. One is on top and the other is on the bottom. They both work. Thank you
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Thursday, November 2nd, 2017 AT 5:56 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Yes it is 2008 sport with 3.7 l.
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Thursday, November 2nd, 2017 AT 6:04 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
I would replace the mode actuator which is on the passenger's side.
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Friday, November 3rd, 2017 AT 1:17 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Do I have to remove the dash again or can I reach through the glove box? Thank you.
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Friday, November 3rd, 2017 AT 2:33 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Ken, here is an image if what I think is the mode actuator. This is right above the blower motor which is working on the passenger side. I can see it through the glove box. Is this it? Thank you so much for the help.
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Friday, November 3rd, 2017 AT 4:06 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
It is kind of hard to tell but it should be, It look like the same area the diagrams shows. When you remove the actuator manually move the door with the HVAC running that way you can tell which actuator does what.
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Sunday, November 5th, 2017 AT 11:54 AM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Replaced the mode door still no heat. Ken, replaced mode door and recalibrated the blend door and still cold air
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Saturday, November 11th, 2017 AT 1:49 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you grab onto the heater hoses after the engine is warmed up you see if they are warm? Here is a guide to help. Can you check the coolant level as well?

https://www.2carpros.com/articles/car-heater-not-working

Please let us know what happens.

Cheers, Ken
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Monday, November 13th, 2017 AT 8:45 AM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Yes they are very warm, Coolant is full. I think it is a blend door issue. My grandpa put it in and he is a good mechanic. I'm thinking calibration issue with the blend door
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Thursday, November 16th, 2017 AT 9:06 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
That could be. I would try to reset the system by removing the negative battery cable from the battery and holding it to the positive battery terminal for 5 minutes to discharge the system and let it relearn. If that doesn't work here is the reset guide from the manual.

Below

CAUTION: Do not exchange A/C Heater Controls from vehicle to vehicle. Software versions differ between models and model years. Installing an A/C Heater Control with software that is incompatible for a given vehicle can result in either improper or failed HVAC system operation.

A/C Cooldown Test

The A/C Cooldown Test:

is actuated with a scan tool.
Tests A/C system performance based on evaporator temperature sensor input.
Will fail if evaporator starting temperature is below 18°C (65°F) when initiating the test.
Will pass if the evaporator temperature drops 11°C (20°F).
Indicates test outcome by displaying one or more test status messages on the scan tool. These messages will clear after paging back out of this test function. Therefore, is it important to note all of the messages before doing so.
Will cause the A/C status indicator to flash while the test is running.
Actuator Calibration Function

The Actuator Calibration function:

is actuated with a scan tool.
Homes and repositions door actuators.
Monitors for door span faults. Door span faults (XXX Door Travel Range Too Large or XXX Door Travel Range Too Small) will only display after calibration.
Will cause the electric backlight (EBL) status indicator to flash while the test is running.

Please let us know what happens.

Cheers, Ken
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Thursday, November 16th, 2017 AT 10:44 AM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Ken, thanks for all the help. We now have heat. The top actuator on the driver's side that attaches to the blend door was out of calibration.
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Tuesday, November 21st, 2017 AT 5:14 AM
Tiny
KEN L
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Nice work, we are here to help, please use 2CarPros anytime. Can I ask how you calibrated it?

Cheers, Ken
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Wednesday, November 22nd, 2017 AT 10:55 AM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
I'll have to find out. I was out of town and my ex-father in law who is a very good mechanic heard that I was having problems and he looked at it while I was gone. I was told he recalibrated the actuator. I'll see if I can get more details. Thanks again.
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Thursday, November 23rd, 2017 AT 1:49 PM
Tiny
KEN L
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That would be great so it will help others :)
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Friday, November 24th, 2017 AT 5:14 PM
Tiny
MIKE R1025
  • MEMBER
  • 14 POSTS
Ok here we go, my step grandpa and his son replaced the blend door. Still no heat. I flushed the heater core, replaced the thermostat, flushed the radiator and replaced the actuator on the passenger side above the blower. Still no heat. I then replaced the control panel and still no heat. My ex father in law looked at it while I was out of town and found the wires for the two actuators on the driver's side were crossed up. I guess when they replaced the blend door, they got the wires crossed. Wires were switched and now we have heat. Thanks for all the help.
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Saturday, December 16th, 2017 AT 5:38 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken
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Saturday, December 16th, 2017 AT 11:15 AM

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