I own a 2000 Ford F250 Superduty with a 7.3 Power Stroke and Manual transmission. The AC blows cold at Interstate speeds (70mph), buty in city slowing down, stopping and starting, it stops blowing cold? I've taken it to several ac mech's. It is charged good and not leaking. Any ideas what could be wrong?

 

Is there anything blocking air from going through the condenser? Also Check out the fan clutch, sounds like it could be always freewheeling and not engaging when temp goes up and more air is required to be moved through the radiator and A/C condenser.

 

There is nothing blocking the air. Even when it stops cooling the air still blows, only hot air. I know very little about auto ac but, I had the "orfice?" replaced the first time it worked after the system was flushed and recharged. Worked great for a little while then stopped again.

 

Even if the orifice were to be blocked again it would not blow cold air at 70 MPH.
You have something not taking the heat away from the condenser and it points to the fan clutch assy not pulling cooler air over the condenser to remove the heat in it so it can return to a liquid state and go back to remove heat from the inside of the vehicle.
Can you see if the engine fan is really working and making a lot of noise by pulling air through the radiator and A/C condenser?

 

Compressor is still turning/cycling when the temps go warm?

 

It looks like there is technical problem in the compressor and many factors involved that affect the actual output temperature at the dash AC vents.

 

....I'd also suspect the compressor.

 

OK...I'll sling a couple of questions out here for you...

Lets start with...Why was the system "FLUSHED"? I read nothing in the post as to why. Also, since the system was opened, the accumulator should have been replaced, don't rear where that has occured.

I've posted zillions of A/C responses in various postings, so I may be considered **** about what should be done when an A/C system is opened or repaired for a compressor failure.

But like I tell folks whos vehicles I work on..."If you're not going to let me do it RIGHT the first time, take it someplace else".

 

If Freon checks ok then Check the electric clutch, to do this the engine needs to be running with the AC on look at the clutch on the compressor it should be turning. I have found several of the Ford F250 and 350 that after alot of usage start disengaging at low speeds, I found other than replacing all it took was to shut the engine off their are three metal flat springs that attach the clutch to the center of the compressor pulley where the flat springs are attached to the round pulley use a small chisel and hammer and give the rivit holding the flat spring to the pulley a lite tap on each of the three rivits this will close the distance between the clutch and compressor belt pulley and most likely fix loss of cooling at low speeds and some cases high speed.

 

Can the AC Compressor clutch be replaced with the compressor on the engine? (Just a general curiosity question)