Restart AC poor performance

jasonstang · May 21, 2018

Has anyone noticed AC or climate control doesn't want to quickly cool down cabin until 5 minutes later. It almost feels like the interior temp sensor is not reading the temperature correctly.
AC runs normally if parked more than 5 hours but if I just go somewhere for 10 minutes and get back in the warm car, AC only blows low air unless I press max AC in order to cool down the cabin quickly.
It almost feels like the sensor is reading high until 5 minutes later. Is there a way to test the sensor?

Fleco17 · May 23, 2018

Mine is doing the same also. I shut it off and restart it and it seems to get colder but the center vent seems to be colder than the other two right beside it. I understand that it's right beside the evaporator that still doesn't explain why it's colder than the other two. Thinking of taking to the dealership.

jasonstang · May 23, 2018

Fleco17 said:
Mine is doing the same also. I shut it off and restart it and it seems to get colder but the center vent seems to be colder than the other two right beside it. I understand that it's right beside the evaporator that still doesn't explain why it's colder than the other two. Thinking of taking to the dealership.

To me it feels like software issue because it would work normally after a while and sometimes always work upon restart.

EcoBoostang · May 24, 2018

All sorts of reports of AC issues. Evaporator failures, low refrigerant levels and blender door issues. Dealership if it’s in warranty for sure.

Fleco17 · May 24, 2018

Does your seem to "surge" on the fan while it's in the 2nd or 3rd position?

white15gt · May 24, 2018

Mine does the same thing. I don't have the Auto climate control, my car is a base, but it is still an electronic system. When I did a data capture on IDS, I could see "Int_Temp" sitting pretty at 69-70 degrees, and "AC_Com" (ac command) was on. All of a sudden, INT_TEMP dropped to 35 degrees, AC shuts off (even though the knob is still full cold). Shut the system off, turn it back on, everything is normal again. Pretty sure that the interior temp sensor is bunk.

barrykaye1001 · May 24, 2018

jasonstang said:
Has anyone noticed AC or climate control doesn't want to quickly cool down cabin until 5 minutes later. It almost feels like the interior temp sensor is not reading the temperature correctly.
AC runs normally if parked more than 5 hours but if I just go somewhere for 10 minutes and get back in the warm car, AC only blows low air unless I press max AC in order to cool down the cabin quickly.
It almost feels like the sensor is reading high until 5 minutes later. Is there a way to test the sensor?

Same problem here. I pulled and cleaned the cabin air temp sensor and it seems to be better. Not perfect but better.

Grinder67 · May 24, 2018

barrykaye1001 said:
Same problem here. I pulled and cleaned the cabin air temp sensor and it seems to be better. Not perfect but better.

Where is that sensor located?

jasonstang · May 24, 2018

Fleco17 said:
Does your seem to "surge" on the fan while it's in the 2nd or 3rd position?

No it doesn't surge or what. I can manually turn up the speed but automatic mode the air is tiny for like 5 minutes. It feels like the interior temperature sensor is not reading the correct temperature as if it's stuck on the last temperature which is lower than current cabin temperature which to me sounds like a programming issue.

jasonstang · May 24, 2018

Grinder67 said:
Where is that sensor located?

Right side of the steering column panel. You can see the small opening on that panel.

jasonstang · May 24, 2018

barrykaye1001 said:
Same problem here. I pulled and cleaned the cabin air temp sensor and it seems to be better. Not perfect but better.

Yea I don't think it's a sensor or connection issue. It's programming like the temperature is not updating correctly.

barrykaye1001 · May 25, 2018

jasonstang said:
Yea I don't think it's a sensor or connection issue. It's programming like the temperature is not updating correctly.

I thought the same thing. Dealer said it's working fine. When it's 90 degrees outside, the system should come on max cold and max speed automatically but mine didn't. Dealer said it's how the system is programmed. I went digging around the internet and read about the cabin air temp sensor.

From what I've read, the HVAC system uses the cabin air temp sensor for a couple of things. It provides info to the system to control the blend door that routes air between the evap coil and the heater core. This controls the temp of the air coming out of the vents. The system also uses it to set the blower speed.

Removing the sensor is easy. The small panel with the vertical slots is held on with three clips. Pull on the panel from the top where it meets the instrument cluster and it will pop off.

Inside the sensor there's a thermistor. It's the thing sticking up from the controller board. There's also a small fan that draws air in to the sensor. The air moves across the thermistor and it tells the system what the temp is.

With my sensor, there was a coating of dust on the thermistor and on the fan. I used a Q-Tip and some rubbing alcohol to GENTLY swab the dust off the thermistor. Be really careful because if you break it, you'll need a whole new sensor. I also cleaned the fan blades.

Something else to try is resetting the outside temp sensor. With the car on, press the A/C and RECIRC buttons at the same time and then, within 2 seconds, press the A/C button again. The car does this automatically after you drive for a little while but I went ahead and did a manual reset.

While the system isn't perfect, it seems like it works more like it should.

Fleco17 · Jun 7, 2018

barrykaye1001 said:
I thought the same thing. Dealer said it's working fine. When it's 90 degrees outside, the system should come on max cold and max speed automatically but mine didn't. Dealer said it's how the system is programmed. I went digging around the internet and read about the cabin air temp sensor.

From what I've read, the HVAC system uses the cabin air temp sensor for a couple of things. It provides info to the system to control the blend door that routes air between the evap coil and the heater core. This controls the temp of the air coming out of the vents. The system also uses it to set the blower speed.

Removing the sensor is easy. The small panel with the vertical slots is held on with three clips. Pull on the panel from the top where it meets the instrument cluster and it will pop off.

Inside the sensor there's a thermistor. It's the thing sticking up from the controller board. There's also a small fan that draws air in to the sensor. The air moves across the thermistor and it tells the system what the temp is.

With my sensor, there was a coating of dust on the thermistor and on the fan. I used a Q-Tip and some rubbing alcohol to GENTLY swab the dust off the thermistor. Be really careful because if you break it, you'll need a whole new sensor. I also cleaned the fan blades.

Something else to try is resetting the outside temp sensor. With the car on, press the A/C and RECIRC buttons at the same time and then, within 2 seconds, press the A/C button again. The car does this automatically after you drive for a little while but I went ahead and did a manual reset.

While the system isn't perfect, it seems like it works more like it should.

Well I just came back from the dealership. They vacuumed the Freon out and did a vacuum test to see if it held vacuum. All checked out, but they did find an issue with the sensor that was mentioned above. I mentioned it to the tech and he agreed. They ordered the sensor and will have to do a little reprogramming on the ac side. Will be going back on Tue since it only has a little over 8k miles.

jasonstang · Jun 7, 2018

Fleco17 said:
Well I just came back from the dealership. They vacuumed the Freon out and did a vacuum test to see if it held vacuum. All checked out, but they did find an issue with the sensor that was mentioned above. I mentioned it to the tech and he agreed. They ordered the sensor and will have to do a little reprogramming on the ac side. Will be going back on Tue since it only has a little over 8k miles.

That is interesting. When I had my 2016, I didn't remember mine behaved like that. 2017 they reprogrammed the HVAC software to allow climate control seats to come on after restart (2016 you have to manually turn back on after restarting).
Maybe they screwed up the software.
Let me know how it works out.
My problem is if the car is out in the heat all day, automatic fan speed turns on full blast right away no problem. If the car has been driven for a while and the cabin has already cooled down, the AC automatic fan speed is uselessly low after restarting say after maybe 5-10 minutes of parking outside in the heat. I can manually change fan speed no problem just the automatic fan speed the issue.
Also, I remember if the cabin is very hot from parking outside all day, doesn't the recirculation turn on automatically until the cabin has been cooled down to a certain point? Mine never does even in 100F degree weathers.

Fleco17 · Jun 7, 2018

jasonstang said:
That is interesting. When I had my 2016, I didn't remember mine behaved like that. 2017 they reprogrammed the HVAC software to allow climate control seats to come on after restart (2016 you have to manually turn back on after restarting).
Maybe they screwed up the software.
Let me know how it works out.
My problem is if the car is out in the heat all day, automatic fan speed turns on full blast right away no problem. If the car has been driven for a while and the cabin has already cooled down, the AC automatic fan speed is uselessly low after restarting say after maybe 5-10 minutes of parking outside in the heat. I can manually change fan speed no problem just the automatic fan speed the issue.
Also, I remember if the cabin is very hot from parking outside all day, doesn't the recirculation turn on automatically until the cabin has been cooled down to a certain point? Mine never does even in 100F degree weathers.

I will update after the visit to the dealership. Also I will be asking more questions.

Restart AC poor performance

jasonstang

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Fleco17

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EcoBoostang

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white15gt

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