I have a 2004 F-350 6.4L 4x4 Powerstroke and cannot get the A/C to blow out. I have replaced the fan motor or blower, and the speed control resistor inside the cab of the truck. It looked like the compressor was working and noticed that when I took the cap off where the freon goes, it was slightly hissing. I dont know if that is why the a/c wont come on or if it is something I am overlooking. Please help since its been over 100 degrees everyday

 

Are you saying there is no air flow in any position? Is the fuse good?

 

Yes, ive gone through the fuses and all were good.

 

Check the refrigerant lines at the evaporator. If both are cold, the problem is in the air handling and distribution system, not the sealed AC portion of it.

Try to be specific about describing symptoms and observations. Is your problem "no blower operation" regardless of climate control mode?

 

Yes, the blower will not run and the lines are hot, not cold as usual. I have replaced the Blower Control Switch, Blower Motor, and the Motor Resistor. How can you check the relays in the fuse box? I was thinking it could be a relay?

 

No offense intended, but, based on your posting, I think you need to get someone who is familiar with vehicle AC systems to take a look at it for you. It is really difficult to diagnose a problem like this without being there to look at it.

 

Ok, the port where you hook up the freon can to, it is slightly hissing when I take the cap off. I dont know of any other way to explain that one. The a/c compressor is engaging. I cannot get the blower to run so I replaced it along with a blower control switch and a motor resistor. Do you have any insight on what else I need to look over?

 

Well, you should NOT hear any hissing noise with the cap off of the low side port as you described. However, that problem is not related to the blower not coming on. I would look at a wiring diagram and get a meter and start troubleshooting the electrical reason why the blower is not coming on. Check fuses, measure voltages, etc. Then, after you get the blower working, take a look at the rest of the system. Put on a set of gauges and measure the pressure on both the low and high side of the system. That will give a good idea of where to look for the problem. It is often difficult to tell precisely where a sound is coming from when the engine is running. I would get the blower working first, then re-evaluate what needs to be done.