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wharriso

No Heat

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I drained and re-filled the coolant from my 2017 Lincoln MKZ several months ago and did not know I had a heat problem till yesterday because it was so warm outside till now.  The hoses are hot on both sides of the heating hoses going into the firewall so I figured the heater core must have coolant in it.  When I turn the heat all the way up, the driver side blows slightly warm air while the passenger side blows cool air.  I thought about blend doors so I put my hand on the passenger blend door while moving the temp from low to high but I see no movement and I feel no motor activity.  Is there a fuse that could be blown that controls this?  I have no idea what could be causing this.

Thanks in advance.

 

BTW, I don't think its a blower motor because there hear that running and I can adjust the speed, it just blows cold air.

Edited by wharriso

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Since the issue seems to have started after your drain and refill of the cooling system, I think it likely you have air in the system. You do need to bleed the air out of the system when you refill it. Try Googling for the proper procedure. 

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On 10/31/2021 at 7:06 PM, leftoverture said:

Since the issue seems to have started after your drain and refill of the cooling system, I think it likely you have air in the system. You do need to bleed the air out of the system when you refill it. Try Googling for the proper procedure. 

At this point, I think the problem must be a fuse.  You can drive this car around in the cold and it will stay warm inside the passenger area even if there is not heat blowing.  It appears that the heater core is warm, it is just not blowing heat.  I changed the blend door actuator on the passenger side but while there was no blend door, I started the car and both sides were blowing slightly warm air.  After installing the new blend door, things went back to the way the were, indicating to me that no power is getting to that blend door.  So now I am going through the painful process of checking every fuse in sight and trying to reach fuses that are not in sight.  Does anyone know if there is some kind of HVAC reset that can be done to maybe recycle the system?

Edited by wharriso

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Hi wharriso. Is your 2017 MKZ still within the 4 year/50,000 mile New Vehicle Warranty?

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2 hours ago, wharriso said:

At this point, I think the problem must be a fuse.  You can drive this car around in the cold and it will stay warm inside the passenger area even if there is not heat blowing.  It appears that the heater core is warm, it is just not blowing heat.  I changed the blend door actuator on the passenger side but while there was no blend door, I started the car and both sides were blowing slightly warm air.  After installing the new blend door, things went back to the way the were, indicating to me that no power is getting to that blend door.  So now I am going through the painful process of checking every fuse in sight and trying to reach fuses that are not in sight.  Does anyone know if there is some kind of HVAC reset that can be done to maybe recycle the system?

Some modules have been known to reset after disconnecting and reconnecting the battery.  Maybe you'll get lucky.  At least it doesn't cost anything.  There may be an engineering HVAC reset procedure, but I don't know if that's a thing.  Maybe someone with Forscan will jump in here to help.  On my Lincoln LSes, there was self-diagnosis sequence of buttons to push on the EATC that would display fault codes, but IDK if that exists in these cars.  I think that at this point, you need to have the system read for any codes.  There are a number of cabin sensors in these cars, and there's a possibility one of yours may be malfunctioning.

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On 11/10/2021 at 5:54 PM, bbf2530 said:

Hi wharriso. Is your 2017 MKZ still within the 4 year/50,000 mile New Vehicle Warranty?

Nope

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3 hours ago, wharriso said:

Nope

 

 Hi wharriso. Then try following drolds1's recommendations.

 

Keep us updated and good luck.

Edited by bbf2530

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On 11/10/2021 at 7:22 PM, drolds1 said:

Some modules have been known to reset after disconnecting and reconnecting the battery.  Maybe you'll get lucky.  At least it doesn't cost anything.  There may be an engineering HVAC reset procedure, but I don't know if that's a thing.  Maybe someone with Forscan will jump in here to help.  On my Lincoln LSes, there was self-diagnosis sequence of buttons to push on the EATC that would display fault codes, but IDK if that exists in these cars.  I think that at this point, you need to have the system read for any codes.  There are a number of cabin sensors in these cars, and there's a possibility one of yours may be malfunctioning.

Actually, I have a pretty good scanner, a Launch x431 V.  It brings up no codes,  But I did notice a few things, there is very slight heat coming out of the driver side vent, but only cold air coming out of the passenger side.  I went ahead and replaced the passenger side blend door actuator.  With the old actuator removed, there was slight heat coming out the passenger side as well but when I put the new one back in, the cool air came back.  That indicates to me that the actuator is just not getting power so I am now thinking I have either a blown fuse somewhere or a reset procedure is needed.  I did try disconnecting the battery, no luck.  Fuses under the dash are really hard to reach but I will try to check them today.

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