Heat goes down at red light

Discussion in 'Generation 4 - Maintenance & Troubleshooting' started by Shokev, Nov 6, 2019.

  1. Shokev

    Shokev SHO Member

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    Anybody every have a problem we’re there heat goes down when there stopped at a red light. Car is at operating temp and heat was on 74 degrees. I don’t think it a cab filter. Just noticed this problem today. I have a 2013 sho


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  2. bpd1151

    bpd1151 Lurking Around

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    Top off your coolant overflow/degas reservoir.

    Even slightly below the fill line will cause issues with poor heat output in the cabin.

    Start there, as that is THE MOST common issue.

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  3. Shokev

    Shokev SHO Member

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    Ok thanks


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  4. only_1

    only_1 New Member

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    I had the same problem and this was my fix as well. I am surprised at how sensitive it is. I am not used to fords in general. Just that little bit of fluid in the reservoir made a big difference in heat output in my car.
     
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  5. sdpatt

    sdpatt Sr. SHO Engr.

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    Is the air blowing from the vents less warm, or is there less air flow from this vents? If the latter, the dampers may be redirecting the flow to the defroster ducting and this would be due to a vacuum leak, likely in the small diameter plastic hoses that penetrate the firewall. If the former, it means less warm coolant to the heater core. If the cooling system is filled and this is still happening, this would be due to the flow being improperly throttled to the heater core by the ECC head. That would probably be through the vacuum actuators too.
     
  6. Shokev

    Shokev SHO Member

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    Found a coolant leak under the surge tank/overflow. Most likely causing my heat issue


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  7. SHOdded

    SHOdded SHO Member Supporting Member

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    post a pic of location please?
     
  8. Shokev

    Shokev SHO Member

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    I dropped it off at the dealer since i didn’t have time to mess around with it i will post pics and update when they call me


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  9. IfTheSHOFits

    IfTheSHOFits New Member

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    I had the exact same issue and it took several visits to the dealer who had to talk to Ford Engineering to figure out a fix. Coolant level could have been a possibility, but that was not an issue in my case. If the system had recently been drained, there was a special procedure to ensure the air gets out of the heater core (the front of the car needs to be somewhat higher in the rear). However, this didn't help in my case either.

    What the issue ended up being was a check value that controls the flow through the heater core. This valve stuck in my case which created the exact same symptoms. You have plenty of heat so long as the RPMs were north of 1,500, but at idle, the heat quickly dropped. They replaced the check value (can't recall if it was in the hose assembly or just the valve) and the issue was corrected.

    In my case, there were no issues with blend doors or any other items that were involved in this concern. It was quite a pernicious problem to solve and I'm sure the dealer was tired of seeing me. :). Hope that helps.
     
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  10. Shokev

    Shokev SHO Member

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  11. Sgtmeatsauce1

    Sgtmeatsauce1 2013 SHO +pp

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    I had the air bubble problem, car kept over heating until it was burned with proper procedure...
     
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  12. SHOdded

    SHOdded SHO Member Supporting Member

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  13. Dirty Harry

    Dirty Harry New Member

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    I have learned over many years in many different cars that if you drill a 1/8 inch hole in your thermostat that you will have far less problems with air getting trapped in your cooling system.
     

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