Sorry for the long post but I like to provide you with as much info as possibly. I have a 2013 FX2 5.0L 502A with MFT Dual Zone A/C.
I know this is a 2 year old thread but I would like to give you gives some insight to the ****** A/C that the F-150s and Raptors have. My truck since new would cool but it was NEVER freezing. My wifes 06 Mazda Tribute is colder than my truck.
I bought a pocket thermometer to put in the vent to monitor it for a while. I found that my vent temps would range from 48-55* NO MATTER WHAT OUTSIDE TEMP WAS. I have seen 48* in 92* weather in the middle of a sunny day and I have seen 52* in 68* weather while RAINING. I was bringing my sick 12 month old son to the doctor one day, his doctor is a hour from our house. The AC was on temp setting LO, Max, Recirc, Fan on HIGH. After the hour drive I NEVER had to turn the air down, once we got to the doctor I took my son out his car seat and he was sweating. Granted he just broke a fever but still that's unacceptable to me
Brought it to the dealer I bought it from and told them I never seen anything colder than 48*. They kept it over night and give me a rental, Black 2014 Silverado. The next day I pull the Silverado out the carport and park it in my neighbors driveway while I pressure washed my driveway. Dealer calls and said my truck was ready. I jump in the Silverado that's been baking the in the sun for 6hours crank A/C to Max and before I got to the dealer, 6 miles a way I was freezing and had to turn it down. I get there and they tell me they got 42* out of the vent and that's within spec. I called BS and asked them to show me. Best they could show me is 50*. Being pissed I got on the F150Forum.com and contacted the Ford Service Rep. They had me bring it to another dealer, I did and I got a Dark Blue 2014 Kia Sorento as a rental. It got 36* vent temps. Dealer called and said that they replaced the expansion valve. On the way home it was the same temps as before, 48-52*. Contacted the Ford Service Rep and they asked me to bring it back in. Got a White 2015 XLT F-150, its AC was freezing. The next day they called and said that after speaking with Fords Engineers they say its within spec and no further work will be covered under warranty.
Onto the good part.....
This ****** A/C is a problem for ALOT of the members on the forum. There was a couple members on the forum that thought that the 24oz that Ford says the system takes is actually low. So I had a friend of mine hook the gauges up and my pressures were low. To get my pressure to where he thought they should be we added about 16oz of 134a to the system, so IF my system had the correct 24oz before, I now have 40ish ounces. On the raining drive home from his house I got 39-42* vent temps. The next day there were back to the normal 48-52*.
The same friend that added the Freon to my truck also has a IDS system and while trying to figure out what the issue is with our A/C he try an experiment. Like me and the other members on the forum we noticed that out compressors only stay engauges for 8-10 seconds at a time. So with the IDS system he DEACTIVATED the computers control of the compressor and he tool control of it. With the computer controlling the compressor he was getting 42-46* vent temps, with him controlling the compressor he was able to get the vent temps to 19*. This is obvious to cold due to the increased chances of the evap freezing up. But we learned something! We learned that our A/C is ****** because that's how Ford wants it to be. The programmer in the computer tells the compressor to cycle to often based off the evap temp sensor. So with this new found information another member took it a pawn himself to find a solution. What he found was that if you install a 820K resistor onto the evap temp sensor it tricked the computer into thinking the air was warmer than it actually was and kept the compressor engaged long. The results were 39* vent temps.
Heres are some pics, info, & links to see what he and others have done to improve the A/C. The said part is that all Ford needs to do is to rewrite the program to let the compressor stay engaged longer but I seriously doubt we will see such update.
Chart to show resistance values and temps for different resistors
How to read this:
The values along the top are the new resistor values
The values down the left side are what the OEM Thermistor is reading
The values in the chart are what the PCM will read with the new resistor installed (ohms on left, DegF on right)
This chart is straight out of Fords Service Manual.
Links
Resistor Compressor Cycle Fix
Proof Our AC Is More Than Capable
The Story Of How Ford Gave Me The Big Ol D
How-To Make Your A/C A Little Better For Under $6
Hope you enjoy this info, if anyone has connections at Ford on a upper level please tell them we want a software update with different factors for how the evap temp sensor causes compressor cycling in conjunction to temps.
Wayne
