A/C not cold and not low on refrigerant

[mor4wd]

My A/C has not been cold so I checked my lowside pressure and found it was about 20psi. I bought a couple cans of synthetic R134a and filled the system up to 40psi. The air got slightly colder but it started making a terrible noise when you first started the compressor (not on the subsequent cycling of the compressor). The noise varies in severity, sometimes it sounds similar to a squealing belt, but not quite the same. Other times it sounds like a blowoff valve releasing 200psi. I cant figure it out. I let pressure back out of the high side down to 30psi and it didn't make a difference. Also the air is not cold, I'm not expecting it to be "R12 cold" but this is miserable. Hopefully somebody can help me out. I'm getting ready to take it to an A/C guy or the dealer, but I'd like to fix it myself. Thanks

[greasltn]

Just adding 134a will damage the system if you don't need it. It could be an orifice tube or the compressor itself. You really need to hook it up to a manifold system to find out what's going on, before you grenade the system.

[BlueF350]

My a/c improved after I blew some connector gasket and dumped the factory coolant on my drive. The dealer fixed the gasket and recharged the system. Better but still not great. My wife's Maxima has better a/c. Not good with 2 Labs in the back.

[mor4wd]

Got my system evacuated yesterday. They measured the coolant that was in there and it turns out that the Ford system is more of a low pressure system than what is typical because I had 3.6 pounds of refrigerant in it and it only calls for 1.67 pounds, but I had only filled it up to 35 psi on the low side. They put new refrigerant in to the specs and it works great with no more noise. Thanks for your guy's help.

[Big Angry Hillbilly]

That noise you heard was the compressor trying to compress liquid refrigerant. Liquid does not compress very well.

You should find the leak, or you will be doing this again next summer.