Weird A/C problem

[mtb9153]

Last week we had some 90 degree days here in the south bay area and I was using the A/C constantly.  While driving around I noticed the A/C air flow seemed less than usual even when Max A/C was selected.  Usually with that setting there is a ton of air flow and allot of air noise associated with it.  However there wasn't and the flow of air was decreasing by the minute and the temperature was rising in the cabin quickly.  I also noticed a rushing air sound coming from the dashboard sort of like something was restricting the flow of air forcing the cooled air to pass through a smaller path.  My first guess was maybe a vacuum controlled door was sticking partially open/closed, a common problem with allot of the GM cars I've owned in the past.  When I got to my destination I shut off the ignition and left the car.  When I came back and restarted, the flow of A/C air pressure was normal and the air restriction sound was gone.  My cool air returned as well, getting down to 48degrees according to the thermometer I have placed in one of the center vents.  So in conclusion it appears I had some sort of A/C vacuum control malfunction which corrected itself by stopping and starting the ignition.

[jdbob]

The HVAC doors are controlled by stepper motors on our cars, not vacuum. Probably just a confused computer....

[ScubaDadMiami]

It sounds to me that the flow of air was not coming from the front vents, but instead from the defrost area. That was the difference in the sound. I would start by checking which vents are activated, and making sure that you see that AC is turned on.

[mtb9153]

ScubaDadMiami this might be a possibility?  I didn't check for air flow up on the dashboard with my hand.  Thanks for the thought, next time it happens I"ll be sure to check for this.  I do know for a fact that the A/C was on Max Air and the highest blower setting.  There was very little air flow and allot of rushing air noise

Edited May 12, 2014 by mtb9153

[ScubaDadMiami]

Oh, I think that on Max it automatically goes to the right vents. Not positive, but I think so.

[andeeca]

We had the same thing happen last month coming down I-5 in a heatwave.  Flow would start off high and cold and then we'd notice it was low flow and not cold, but slightly cooler than 100 degrees outside.  When we stopped and started up again, it worked for a while and then the same thing would happen.  It's at the shop now for oil change and they are supposed to check AC.  I don't have much confidence in them though. 

 

Update, never got any new info.  Worked fine last month going through the Arizona desert, but then going to San Diego last weekend in only 74 degrees it was acting up again.

Edited July 7, 2014 by andeeca

[METROMAN]

Just noticed this thread. Your issue is also exactly what I posted about under my thread titled AC issue, 3 days short of a year ago. Restarting the car seems to be the only way to fix it when it happens. Reboot the Microsoft system.

Edited June 14, 2014 by METROMAN

[Baldrick]

We had this on a 3 hr road trip recently - the air stopped flowing, but still made noise. It went in to the shop but they couldn't diagnose anything. It was as if the AC just got tired and needed a break.

 

It then happened again last weekend. My wife used the touch screen (she tried the manual controls first but nothing happened) to try changing the air flow and it started working again.

 

The car's going back in for other unrelated work - steering wheel controls not working - this week so Ill let the garage know our work around.

[JohnnOhio]

Noticed this last week to. It was cooling the car nicely in AUTOMATIC MODE then the blower slowed as normal. Noticed it getting warm inside so I turned it on manual mode and turned up the blower speed. The air was hardly coming out of the vents. Started working on its own a 15 minutes later. Switch back to auto mode and worked fine.

 

Going in for oil change in a few days. I'll have it checked out.

[catsailor]

same issue with my car today with +95 outside heat. Anybody figure this out because when I used my car 2 hours later everything was back to normal.

[METROMAN]

Ours is screwing up again. 3 times this week. Only way to get it working again was to turn off the car & start everything back up.

Anybody notice that with the hotter temps, 85+ that the system isn't cooling enough? Usually run the system at 73 but lately having to run it at 70-71 to keep things cool.

[FordService]

Hi everyone,

 

If you're having this AC concern, drop me a PM with your name, phone number, VIN, mileage, and dealer info. I'll see how I can help.

 

Ashley

[ptjones]

I think I have noticed this too.  I'm wondering if the evaporator is getting frozen up, because if I go to just vent(turn A/C off) for 5min. and back to A/C it seems to work. I usually don't use AUTO A/C unless my wife is in the car. LOL :)

 

Paul

PS: Don't consider this a significant problem, don't use it unless I have too. It's all about MPG's. :shift: LOL :lol2:

Edited July 9, 2014 by ptjones

[mlsstl]

I vote for PTJone's answer. I've had this happen on other cars before, usually when it is very humid out. The evaporator coil freezes over to the point that the air flow is blocked. Running the blower fan on high with the AC off usually fixes it in a few minutes. There is supposed to be a temperature probe in the coil that detects the freezing and cycles the compressor off and on to keep the ice build-up from happening, but sometimes it just doesn't work well.

[cmascarella]

The A/C problem has been happening to me intermittently for the past two months. Took it to Ford the first time and they ran all kinds of tests on the A/C system - nothing. When it happened again I drove straight to a Ford dealer and didn't turn off my car. The service person told me my "Blend Door Actuator" needed replacing. Going to take it in this week and see if that fixes it. Meanwhile, turning the climate control system off and turning it back on and selecting floor or defrost position helped get the actuator unfrozen. Let y'all know if it gets fixed.

[wab]

Everybody with a older cmax with AC problems check this thread.

 

http://fordcmaxhybridforum.com/topic/2435-ssm-32308-2012-2013-c-maxfocusfusionmkz-hybrid-plug-in-hybrid-battery-electric-vehicles-ac-compressor-noise-low-refrigerant-charge/

 

Low Freon will cause the system to freeze, turning the AC off for just a minute will let it thaw out and start making cold air again, till it refreezes.

[HotPotato]

I was on a long road trip in my 2013 C-Max, ~60k mi on the car, and this happened to me when it was over 100 degrees out with no exits for miles. The AC could be heard but not felt: NOTHING seemed to be coming out of the dash vents. Turning the temperature all the way down, and the fan all the way up, or trying to change which vents the air was directed to, did not help. The blower could be HEARD plenty, and sounded like it was trying to blow through the defrost vents, but could not really be felt at the dash. We found an exit, pulled off, got a bite to eat, came back out, restarted the car and everything worked fine again. (Other than I'm pretty sure I felt a few drips of cold water on my ankle from somewhere under the steering column.) Thought it might be a one-off but it happened again the other day in town. Turning the car on and off did not help, but turning the AC on and off several times seemed to reset it.

 

I have heard that the culprit in this apparently very common issue is a bad evaporator temperature sensor, and that Ford has a TSB about it, and that the fix is an $11 part. Does anyone know anything about that?

 

I have also heard that the issue is low freon. If so, then that ticks me off, because the first guy on this forum to complain about the loud and nasty AC compressor noise common to every 2013 C-Max (audible only outside the vehicle) got more freon added by the dealer, but IIRC after that Ford said the sound was normal for a modern rotary compressor ("they all do that") and did nothing for others.

Edited September 17, 2017 by HotPotato

[plus 3 golfer]

I believe there is a TSB but IIRC, it has the dealer replace the refrigerant, dryer and sensor (likely several $100).  Evaporator core icing is a common issue on many cars not only the C-Max.  Most will likley never notice it as the core won't completely freeze over and completely block air flow.  

 

I suggested in another thread to a poster that  for $11 one should simply change the sensor.  IIRC, the poster changed the sensor and it corrected the issue.  As I explained in the other thread, the sensor monitors evaporator core temperature.  When the temperature approaches freezing, the compressor is turned off so ice does not form on the core.  So, a failing sensor that reads too high could allow ice to build up under moderate to low relative humidity.  Even if the humidity might be low at 100F, when that 100F air is cooled to near 32F, the water vapor in the air will still  condense on the core.  So, if the sensor is faulty, the compressor will still run and cool the core to 32F or lower.  It may take a long time for ice to build up to completely block air flow at low relative humidy and not so long at high humidity.

 

Now the fact that turning the ac on and off might have reset it suggests that there may also be  water in the refrigerant or low charge.  That's likely why the TSB recommends replacing the sensor and refrigerant.  But for $11 change the sensor. :)  ;)

 

EDIT: Here's the link to the TSB.

Edited September 17, 2017 by Plus 3 Golfer

[HotPotato]

I believe there is a TSB but IIRC, it has the dealer replace the refrigerant, dryer and sensor (likely several $100).  Evaporator core icing is a common issue on many cars not only the C-Max.  Most will likley never notice it as the core won't completely freeze over and completely block air flow.  

 

I suggested in another thread to a poster that  for $11 one should simply change the sensor.  IIRC, the poster changed the sensor and it corrected the issue.  As I explained in the other thread, the sensor monitors evaporator core temperature.  When the temperature approaches freezing, the compressor is turned off so ice does not form on the core.  So, a failing sensor that reads too high could allow ice to build up under moderate to low relative humidity.  Even if the humidity might be low at 100F, when that 100F air is cooled to near 32F, the water vapor in the air will still  condense on the core.  So, if the sensor is faulty, the compressor will still run and cool the core to 32F or lower.  It may take a long time for ice to build up to completely block air flow at low relative humidy and not so long at high humidity.

 

Now the fact that turning the ac on and off might have reset it suggests that there may also be  water in the refrigerant or low charge.  That's likely why the TSB recommends replacing the sensor and refrigerant.  But for $11 change the sensor. :)  ;)

 

EDIT: Here's the link to the TSB.

 

You, sir, are a prince among men. Thank you.

[viajero]

This would happen occasionally on my 2013 Energi. I found that switching between floor vents, dash vents, or both a couple times would get the air blowing again. The problem didn’t occur frequently enough for me to bother trying to really fix it.

[skimaxpower]

I experienced this same issue this August in my 2015 C-Max hybrid with ~35,000 miles.

It was a hot day. Had been driving pretty much non-stop with the AC on for about 6 hours. Started blowing harder, but only warm air.

 

Upon turning off the car and waiting an hour, everything was back to normal. I've had no problems since.

[Redshift]

My 2015 had this issue. Took it to the dealer who did the TSB. That was 2 years ago. Never happened again. BTW they don't replace the AC fluid. They just make sure it's full.

[AS2014]

To any fellow CMax owners...I am trying to fiqure out what is causing this...Lately the AC quits blowing , the air is still cold so do not think it has to do with freon. Anyhow to correct the situation, I have to turn off AC for awhile, then put it back on and it works fine till next time. I brought it to my dealer but the problem is it does not do it then , so there is no way to really diagnose unless it acts up. But I been thinking maybe it has something to do with a temp sensor , but not sure if it has one. Really got me baffled , any help appreciated.

[plus 3 golfer]

To any fellow CMax owners...I am trying to fiqure out what is causing this...Lately the AC quits blowing , the air is still cold so do not think it has to do with freon. Anyhow to correct the situation, I have to turn off AC for awhile, then put it back on and it works fine till next time. I brought it to my dealer but the problem is it does not do it then , so there is no way to really diagnose unless it acts up. But I been thinking maybe it has something to do with a temp sensor , but not sure if it has one. Really got me baffled , any help appreciated.

A couple comments:

1. Do you have an SE or SEL?

2. Are you saying the fan shuts down or the fan is still on but no / little air is coming out of the vents?

3. The next time it happens shut the car off and start up with Engineering Test Mode in the left hand display.  There are posts telling how to enable ETM.  Scroll to the screen that shows diagnostic trouble codes and take a pic of it and post if it has stored codes.

4. Better yet spend $30 or so and get the Forscan App for a smartphone and ELM 327 to scan modules for DTCs.  IMO, forscan is worth it just to monitor / set tire pressure and view other data.

5. If the fan is still running and little to no air is coming from the vents, buy a temp sensor and replace it.  I'm fairly sure I posted pics on replacing it. It's accessed  from the driver's side center console foot well area.  IIRC, you pop off a small  cover  on the console and it is easily changed.

[AS2014]

A couple comments:

1. Do you have an SE or SEL?

2. Are you saying the fan shuts down or the fan is still on but no / little air is coming out of the vents?

3. The next time it happens shut the car off and start up with Engineering Test Mode in the left hand display.  There are posts telling how to enable ETM.  Scroll to the screen that shows diagnostic trouble codes and take a pic of it and post if it has stored codes.

4. Better yet spend $30 or so and get the Forscan App for a smartphone and ELM 327 to scan modules for DTCs.  IMO, forscan is worth it just to monitor / set tire pressure and view other data.

5. If the fan is still running and little to no air is coming from the vents, buy a temp sensor and replace it.  I'm fairly sure I posted pics on replacing it. It's accessed  from the driver's side center console foot well area.  IIRC, you pop off a small  cover  on the console and it is easily changed.

Thanks for the response, I have CMax SE. I would say # 5 Fan is still running and little to no air coming out. Will change temp sensor , now that I know it has one. Thanks for the info.