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I had a wierd problem coming home from a weekend trip yesterday. I was towing a light load, about 2000lbs.
The problem was with the AC, or maybe just the FAN.
Everything was fine for a short while, but after I got going, the fan would cut out whenever the engine had to give "power" so to speak.
If I hit a small hill or hit the gas to speed up a little the fan would turn off, then as soon as I let off the gas or went down hill, the fan came back on.
That is the way the system is designed to work. When the AC is on and the load on the engine increases beyond a certain point, the ECM will automatically shut off the AC compressor. The load you are carrying plus whatever speed you are driving at plus the AC being on pushes your truck beyond the limit that the system will allow the compressor to run. I don't know if air temp is also a factor. If you have been having the high temps and humidity like we have had in Michigan the last several days, you AC has been working extra hard. I'd say everything is doing what it is supposed to do.
AC recharge seems like a good choice. I picked up a recharge kit from Walmart and added the large can, it is cooler now. I am going to add another can or two and report back, we will be towing again in another couple weeks, so I should have a good before and after.
i agree with michigan, but it sounds to me like one of the many sensors or circuits that control it are going haywire, and the only solution will require knowledge of all of it. i have a similar problem but it is a high idle condition. i just spent good money on original ford chassis manual, fuel system manual, and electrical/vacuum troubleshooting manual as well. you have to aquire these things like this if youre going to ever get any success. if you are like me you can work on something with only a toilet bowl sitting on the intake of it, and a simple distributor that spins round and round. but open up the hood of a modern vehicle, and it can be quite intimidating.
You guys mentioned that when the AC is on and the load on the engine increases beyond a certain point, the ECM will automatically shut off the AC compressor. I wonder if something like that is happening with my A/C? If I ever have to floor the gas or almost floor it while driving my A/C shuts off for a while. It also tends to shut off randomly for no apparent reason. But it almost always shuts off when flooring the gas. My compressor is really old so I wonder if it doesn't take as much of a load to shut off now? I'm not really hauling anything heavy. Just some boxes of stuff.
The A/C compressor does indeed cut off when you mash the pedal (WOT) as commanded by the PCM. But that is something very different than the inside airflow changing directions (like for example, the air stops blowing out the vent panels and instead blows entirely from the defrost panels). In the latter case, the problem is that their is a leak somewhere in the vacuum system.