http://www.dieselplace.com/forum/smileys/Big Smile.gif I HAVE A 2004 CREW F-250 PSD. WHEN I RUN MY A/C IT CYCLES ON AND OFF. WHEN I PUT IT ON MAX IT ALSO CYCLES ON AND OFF. I LIVE IN THE DESERT. ITS BEEN OVER 100 DEGREES THE LAST FEW WEEKS. MY EXPEDITION, AND MY 2001 F-150 NEVER DID THIS. CAN ANYONE HELP/ THANKS

Is it cool inside the truck? Systems are designed to cycle on and off. The thermostat can turn the compressor off when the temp is cold inside the truck- This prevents the evap coil from frosting up. There is a high pressure switch that shuts the compressor off if the pressure gets too high- fan not working properly, system over charged or temps outside too high. A low pressure switch is also in the system. this will shut it off if freon is low or it is very cold outside. I assume that it is not cool in your truck or you would not be asking. More info will help but the best way is a thermometer inside and a set of guages outside. We can narrow it down with more info.

http://www.dieselplace.com/forum/smileys/Big Smile.gif I WENT TO THE FORD DEALER TODAY. THE TECH WROTE THAT THE A/C TEMP WAS 44 -47 DEGREES. THAT IS NOT WHAT I ASKED THEM TO CHECK. YES IT GETS COLD, BUT IT WARMS UP EVERY FEW MINUTES FOR ABOUT 20 - 30 SECONDS. THEN IT STARTS TO COOL DOWN AGAIN. I HAVE 2500 MILES ON MY NEW TRUCK SO FAR. TODAYS OUTSIDE TEMP WAS A LOW 101. IT HAS BEEN AROUND 108 EVERYDAY. THE A/C IS VERY IMPORTANT UP HERE IN THE DESERT. MY FORD 2003 EXPEDITION DOES NOT DO THIS CYCLING. DO YOU HAVE ANY SUGGESTIONS. I AM GOING BACK TO THE DEALER MONDAY. AGAIN, THANKS FOR YOU HELP.





RON

Has this truck done it since you bought it? If not, then we can rule out that it is overcharged with freon. The dealer needs to find out first which switch is turning the compressor off. An example would be if it is the thermostat shutting it off. I don't know the exact numbers for a ford, but lets say the therm shuts the compressor off when the evap temp gets down to 38 degrees and turns it back on at 42. Maybe it is not turning it on until 46 degrees. This would let the air coming out the vents get warmer for a longer period of time. The low or high pressure switch could be causing a similar problem. I work on heavy duty trucks so I don't know for sure about pickups, but I don't think the high or low switches should be controlling the compressor during normal operation. They are designed to be safety controls. The low pressure switch turns the compressor off usually because the freon charge is low or if it is very cold outside, it might. The high switch will shut it off if the fan doesn't work properly or if the system is overcharged or it is extremely hot out. The dealer needs to put a set of guages on the system and watch what it is doing. They can monitor the temperature inside the truck also, but that obviously is not the only criteria. Experience is very significant in ac work. There are alot of factors involved and all vehicles behave a little differently. The best way would be to set another truck like yours right beside it and watch both systems at the same time. Hope this helps a little.

http://www.dieselplace.com/forum/smileys/Big Smile.gif Hi Jack, yes it has done it since it was new. I talked to the service writer today. I am going to take it back in to be rechecked Wednesday. I am also going to get the first service at 3000 miles. I have read that they may do something to the computer. Flash it I think. Half of what I read says to do it, the other half says don't let them. I drive 90 % around town 8 % freeway, and 2 % towing my tow hauler ( 4500 lbs ). I average about 15 mpg around town. Some of the guys state mileage goes up to 20 after flash. Is this true? Mine was built Nov 2003. I love my truck. Thanks for the info,





Ron

I don't know about the 6.0's. I know some people who are getting that with the 7.3's and others are getting around 12mpg. I just bought a 99 7.3 and am getting about 12, but it sat for a long time so hopefully it will get better. I have heard the same about flashing your computer- alot of info on here about that. Since your ac has been doing it since you bought it, then it could possibly be overcharged. But if they can't fix it, take another one for a test drive and see if it is the same. Good luck. Keep me informed-we learn something everyday.

Have a buddy that just bought an f350 a few months ago, he was having same trouble, took it to dealer. They fixed it on the 2nd visit. Said they added freon. Just fyi

http://www.dieselplace.com/forum/smileys/Cool.gif Well I took my truck in to the dealer yesteday with a copy of Jacks recommendations. My service writer took my copy of Jacks ideas. She gave it to the tech. He did not believe me. What a surprise. He started the truck on the drive, in the shade. Turned on the air to max cooling. Rolled the windows up. Put a thermometer in the vent, and watched. Guess what. It never went below 65 degrees. They removed all of the freon. Installed new freon with a dye so that they can check for leaks.They told me to drive it until it did it again, and bring it back. On the way home it sure got cold. We had to turn it down it got so cold. I let you all know how it goes. Again, Thanks. You should have seen their faces when I gave them a copy of Jacks tests I wanted them to run. It was great. Thanks again,


Ron