Does anyone lose ac in the winter???? I have a 2007 f150 (black on black, of course) that has lost ac, I bought a recharge kit but can't get the R134a into the system. My understanding is that the ac pump has a low pressure shut-off on the pump clutch. Can anyone tell me how to overide this switch so I can get this gas back into my ac?
Thanks in advance.... Its hot out there...
JamieA

 

Yes, it is possible to hairpin this system, but it is really only to be used in diagnosis. If you leave it this way, it can make thing much, much more expensive to repair.
Best bet is to get this properly diagnosed. Start with checking all the fuses.

 

Ahemm it seems u know a lot of engineering Geasemark. Good job! I am impressed. you have explained in such simple terms that I don't think any1 can forget this formula. My AC is still okay but am sure that I am gonna use this method if stops working.

 

Thanks Greasemark,
I'll take your advice on this one.......A penny wise....
JamieA

 

There are a number of things that could keep the A/C compressor from engaging. You could have a bad LOW pressure switch, bad HIGH pressure switch, bad electro-magnetic clutch on the compressor, no/low refrigerant to a worn clutch plate keeping the clutch from spinning the compressor and such. A bad/failed compressor is a gimme.

Assuming no failed compressor, I would start with putting a set of gages on the LOW/HIGH pressure sides to see if you have any type of refrigerant charge on the system. From there, if there is a refrigerant charge, I would recover it to see how much is recovered vs. the required amount for the system. After recovery, I pressure test to 300 PSI with nitrogen. If the pressure holds for 30 minutes, I pull a vacuum for 45 minutes after reaching 29.9 inHg (This also helps in removing moisture in the system as the high vacuum causes water to boil at -70°). Then I see if the system holds the vacuum for 30 minutes. I check for any visible signs of leaks (oil) from the system over time. After the 30 minutes are up, I recharge the system with the proper amount of refrigerant required for the system.

A failed compressor is a completely different sequence of events I go thru to get a working system. I probably wrote that several times within the forum pages.