Hello everyone, I have a 2011 F250 6.2 xlt 221k miles. I have an issue where my AC works sometimes and other times it doesn't work. On the occasion it will work kind of, meaning that it will blow cold for a few seconds (when the compressor clutch engages, but as soon as the clutch disengages I get warm air. My low pressure is at about 30psi and the high is about 140psi (seems low to me). When I bought the truck the a.c. didn't work at all. I pulled a vacuum and put the recommended 29oz of 134a in it. When it works its VERY cold. There doesn't seem to be any ryme or reason (temp, humidity, drive time) as to if it works or not. On occasion (not working) I have been able to turn off the a.c. for a couple minutes and when I turn it on it works. Does anyone have any ideas to look at or things I can check?

 

Feed it some 134a. Seems low to me.

 

I have tried that. This is the second charge I have performed on it. Both times the system was pulled under a vacuum. Thank you for the advice!

 

moisture in the system can freeze on the orifice tube. when you shut it off it melts then works again. vacuum the system till all the water is boiled off then recharge... psi about 250 on a 80 deg day.

 

It doesn't work upon startup. If the truck sits outside all day (11 hour day) it won't work. Other days it works great after work. I used my vacuum pump to vacuum out the system. I ran it under vacuum for about 30 minutes to remove any moisture. Saturday when I left work it wasn't blowing cold on start up. I turned the a.c. off for about 1 minute, when I turned it on it was cold all the way home.

A few weekends ago we were camping, we only got 1 decent drive where it was cold the other trips were hot. Its kind of spuratic as to if it works or not. It usually kinda works (as described earlier) or it just blows hot. Having good air isn't common and is hit or miss. Once again I appreciate your help.

 

Check the clutch gap, it's probably excessive.

Perform a shimectomy, if needed.

 

It has about .025 gap. I was told by the people I bought it from (small dealer) they replaced the compressor.

 

It would have been useful if you had said that initially....

Since the compressor is computer-controlled, you'd need to get into the PCM and read the appropriate PIDs to better understand what's going on and where the control process is breaking down.

 

Sorry that was left out. Is this something someone can do at home? If it is do you have any good links to a tutorial on how to do it?

 

My 2000 had a similar problem. The compressor would not kick on sporadically. There was a high pressure and a low pressure solenoid on the system. They were about $15 each. Try changing the low pressure first. If that doesn't work try the high pressure one. Fixed my problem.

 

You would need a scan tool (or equivalent) with advanced capabilities.

I have no idea if any exist. The needed functionality is built into the scanners that Ford's technicians use, you can probably find it also in aftermarket apps or devices.

 

did they replace the rest of the system when they did the compressor?

My guess is not if it's like most small dealers. it's likely that system has a bunch of crap in it from the old blown compressor.

Richard

EDT: also, what are the pressures when the clutch kicks off? if it's like the earlier trucks the low pressure switch kicks the clutch off around 20-23 iirc

 

Here's a quick video showing what its doing. It has a couple cycles recorded.

https://youtu.be/M8R9j0n476A

 

Find out what they replaced when they replaced the compressor. If the compressor failed and they didn't replace the condenser, oriface tube, and accumulator, and didn't flush the lines and evaporator....

You might need to replace all that again.... Including the compressor.

I just did all that myself with motorcraft parts for about $450-500

Richard

EDT: I figure you are low on freon and likely leaking it out due to bad seals if you keep having to add

 

I haven't had to keep adding. It does hold a charge. I ordered a pressure transducer today. Should be here Thursday.