A/c problem

I have a weird intermittent problem with my air conditioner. I have a 2013 gt premium.

The other day I noticed that the air coming out of one side was a little warmer than the other side, even when set to normal. I didn't feel it was a big deal.

I went on a 3 hour drive the other day and after about an hour I noticed that the air was blowing slower and slower. The air coming out was still pretty cool but it blew slower and slower. It was 90 degrees out so I stopped to get gas and cool off. After I started the car the air was blowing a lot faster initially. Then it went slower and slower again. The next day the air worked fine and blew cold for 3 hours on the way back. I thought maybe something was overheating so I ran the fan on low, but it ran cold all the way back.

It has worked fine for a week since I got back but I haven't driven it for more than about 30 minutes since I got back.

Anyone experience this? Any ideas?

Thank you.

Is this a premium with Navigation and climate control? Or is it a standard pushbutton AC/heater controller that you simply set the fan speed and warmth level on? Or is there any chance you have an after market stereo in the car with an adapter ring that has a custom climate control panel on it that can be purchased aftermarket?

Yes, it has navigation and the touch screen

No aftermarket radio. It is totally stock

There is nothing wrong with your climate control. It is designed to maintain a temperature within the interior. There is an interior sensor that measures air temp which provides feedback for the climate control unit to regulate off of based on the temperature you select. The controller will regulate air flow and supply temp coming out of the vents to optimize for this. IT will also determine which vent to use based on temp setting, (I.E. heat above a certain setting will default from the floor while A/C will be produced from the dash vents and everything else in between). You can fix the fan so it runs steady, you can select which vent mode manually as well, but then you will feel larger changes in supply air as the unit attempts to correct for a rise or drop of temp inside the car.

I doubt there is anything wrong with the unit. Mine worked best allowing the controller full control of supply air and fan speed on its own. ON a long trip as the temp inside the car settles near the temp selected the fans will slow down. If passenger climate is set different the fan for that side will run independently.

Your description right away made me assume you had the comfort group package which includes NAV and climate control (and heated seats I think).

Remember its not like a standard controller you have to keep playing with to get the temp just right and the fan just right on. It does all of that for you.

Read the operator manual. This is one area that Ford did a nice job on with regard to that feature.

If you think that he unit isn't working right get hold of a thermometer and put it in the car and see what it reads with respect to the setting after the car has had time to get the interior temp under control.

My unit worked exactly how you describe your symptom. It's doing its job. Unless there is something I missed. If load changes happen like driving into the sun which generates additional radiated heat into the car it will act differently even though the outdoor air temp may be cooler. I am pretty confident you have no problem aside from getting use to something different. Once you get used to it I think you may like it.

Turn off auto climate and then report back.

Thank you for the reply. the day that this happened I had the temperature set as low as it would go at 60 degrees but the cabin got warmer and warmer as the fan slowed down. It was 90 degrees outside and the cabin was almost 90 degrees inside when I stopped to get gas and to cool off on the gas station. I had the dual controls turned off so it should be blowing the same on each side. It's really weird. I didn't change any settings on it and the next day it blew cold all day and the temp outside was 90 again. Maybe the temp sensor is going out or developing a short?

Maybe the evaporator froze over?

Mustangdale said:

Thank you for the reply. the day that this happened I had the temperature set as low as it would go at 60 degrees but the cabin got warmer and warmer as the fan slowed down. It was 90 degrees outside and the cabin was almost 90 degrees inside when I stopped to get gas and to cool off on the gas station. I had the dual controls turned off so it should be blowing the same on each side. It's really weird. I didn't change any settings on it and the next day it blew cold all day and the temp outside was 90 again. Maybe the temp sensor is going out or developing a short?

Click to expand...

One thing that may have happened is that a piece of debris became caught in the grill in front of the AC condenser which minimized heat removal of the primary AC loop. The system monitors the supply air at the evap coil. If the blockage in front of the condensor was not allowing the AC primary loop to dissipate heat, it could have become saturated causing warmer air to enter the car. Depending on how the logic process is programmed, this rise in heat with the temp set at 60 degrees may have been to begin turning the fans down since nothing else was pulling heat from the cabin.

There are other electrical several factors here that could effect this. The HVAC climate control system is pretty intelligent. It uses a sun load sensor for detecting radiant heat through the windshield and compensates for that as well as having an in cabin temp sensor mounted in a housing with a fan motor that pulled cabin air in for better metering and control of the interior temp with regard to set point. In addition it also monitors supply air temp with a sensor mounted at the evap coil.

If the sun load sensor went flaky or was covered it could effect operation of the unit. This sensor is located in the center of the dash near the windshield. There are two if I am not mistaken.

The "in cabin temp sensor" is located in the center console and also has fan motor that draws interior air into it for better measurement of the interior air temp. If the fan would go bad or the fuse (F30) would open this could cause climate temps to become unstable. The sensor itself could also fail on the side of low resistance (most TH sensors are resistive feedback devices) and could have caused the problem.

As complex as the system is it may be one for a technician. I am only using what knowledge I have of general HVAC theory and the schematics on the 2011 climate control system and giving probable failures based on common devices that would likely be associated with the system internally.

Hope this helps. There is a lot of control strategies going on. Ford def factored more into the equation for comfort on the system than I thought they would.

skwerl said:

Maybe the evaporator froze over?

Click to expand...

That would be an indication of low refrigerant. A very good possibility. Something worth checking. I had the same thing happen on my home AC system (Thanks dad for being an AC&R skilled tradesman). Dad came over with his gauges and explained what was happening. We added refrigerant to the loop and it has been fine and the evap coil has never froze over since.

I will have the refrigerant checked and see if it happens again. I had no idea it had so many sensors on it.

Thank you for your help.

Mustangdale said:

I will have the refrigerant checked and see if it happens again. I had no idea it had so many sensors on it.

Thank you for your help.

Click to expand...

Buy a can of 134A (I think its 134A refrigerant now) with the gauge on it. It's a do it yourself thing. Just follow instructions on the label. Take it to some AC guy at a Goodyear and you can bet he will tell you it needing charging and hit you for the service fee and the can. The AC system point to connect the can is fool-proof. It will only connect to the side of the system you check and fill at. Almost as simple as checking your oil level.

redfirepearlgt said:

Buy a can of 134A (I think its 134A refrigerant now) with the gauge on it. It's a do it yourself thing. Just follow instructions on the label. Take it to some AC guy at a Goodyear and you can bet he will tell you it needing charging and hit you for the service fee and the can. The AC system point to connect the can is fool-proof. It will only connect to the side of the system you check and fill at. Almost as simple as checking your oil level.

Click to expand...

This is not a good idea, you need to see the high side pressure too. If you overpressure the system if can get costly quick!
You need to know the actual specs for pressure in order for that cheap gauge on the parts store can of freon to be of any use.
all makes and models use different systems and different specs, that can literally has a 30 PSI range labeled "good".
On top of that ambient air temperatures affect pressure readings, so if it's not hot outside when you're trouble-shooting with this method, it will always read lower than expected.

Then buy a cheap refrigeration gauge set and check the suction side and pressure side to specification. This site has the tech manuals I have been using for reference on the electrical side. They will have the specification. I'm sure there are plenty of you tube video's on how to read the gauges. Just make sure they are scaled for 134A. You may be able to even rent or borrow from an auto parts store. Either way its you checking it not some AC tech who thinks he has the market cornered because he has 10 lb of F-12 hidden in a corner somewhere. LOL!

Nice full feature video on AC inspection and usage of the gauges. Will make you efficient enough to diagnose and check this yourself. AS you see its not rocket science. Just find the actual operating pressures for the unit.

https://www.youtube.com/watch?v=UW1GDiOa0kE

Had it checked while getting an oil change and it was low on refrigerant. They recharged it with some dye and asked me to come back in a few weeks to see where the leak is.

Thank you for the advice.