jakef

Ok guys, I've read a lot on forums and watched a lot of videos on the subject, but I need some direction with my A/C unit. It is a factory installed 134-A in a 1994 F-150 5.0L. When I purchased the truck the bearing on the a/c was shot, and someone had put a smaller serpentine belt on to bypass the compressor. So new belt, and I had the system Vac'd and replaced the clutch. The compressor was seized, but taking it apart I found no internal damage (and very little oil, maybe from the vac?) So I picked up oil at autozone, rebuilt compressor, installed compressor, clutch, put on a vacuum pump, (only got it to -25), vacuum held fine, so put in 2 lbs of 134-a, clutch engaged on compressor, no dye leaks in system, but no cold air! The low pressure tube didn't get any colder, and the high pressure was incredibly hot before it went to the condenser. I'm thinking clog in the system, but what do I need to replace? Evaporator, Accumulator, Receiver Drier, Condenser? low/high tubes? Any help would be appreciated. Thanks

alsatropine

iTrader: (2)

Did you try spraying down the condensor with a waterhose to see if it got any colder?

jakef

No I haven't. I'll try that tomorrow and let you know what happens... I appreciate the advice

jakef

spraying down the condenser didn't really seem to do much.. I'm starting to wonder if I should take the lines off and try hitting them with a shot from my air compressor... could I do this with all the parts to detect a possible clog?

alsatropine

iTrader: (2)

You could, but seeing what you posted, either your evaporator core is stopped up or the orifice tube is clogged.. Before you try to run the ac again this needs to be fixed or you will burn.up the compressor. Do you have any manifold guages? With this kind of repair you really need to borrow a set. That way we can see your readings. First. You need to evac the system and check the orifice tube. If its clogged with metal particles you need to replace the drier..

jakef

Yea, I have a set of manifold gauges. When I filled it I got the low side to around 110 psi, and the high side was around 130 psi (if i remember correctly). It was a really hot/humid day though, so I didn't really take much account into the readings at the time... the compressor didn't kick off while I was charging it. I didn't think much of it at the time, but that should have been mentioned in my first post.

Nitehawkjr

With the reading being close to the same it usually means a problem with the orifice or the compressor is bad.
I saw where you picked up a rebuilt compressor it has been my experience it's better to go with a new one over a rebuilt one. Also it best to replace the dryer and orifice when replacing the compressor along with flushing the system. If you look around you can find a complete compressor kit along with an O-ring kit and oil for around $200

Generally the readings depending on the temperture should be 35-45 on the low side and 195-230 on the high side. The vacuum should be pulled for about 45 minutes then let sit for 15 min to see if it holds and nothing is leaking.

Also when doing the readings the system should be set to max air and the windows down also if you have one set a fan in front of the truck to put air through the grill.

alsatropine

iTrader: (2)

Look up r134a pressure chart. There you will find the correct pressures for the low side (blue) and high side (red). It will show you the readings in correlation to the temp outside. Also did you add the correct amount of oil to the compressor? If you over oil it then it could give you problems. But check your orifice tube first. If it clogged then like nighthawk said, you need ro replace the drier. The orifice tubes are about 5 bucks and the drier is about 70 I think. Both very easy to replace. Make sure you always use new o rings and dip them in oil before installing them.

jakef

Ok thanks guys... I will order a new dryer and orifice tube. I'm going to order a new compressor too. I added 7 oz of pag 46 oil (per the guy at autozone) when I installed it, but I didn't change the O-rings out... I might as well since they are so cheap. On a side note, when I recaptured the 134 this evening, the dryer got pretty cold and collected a lot of condensation. I'll let you guys know what happens. BTW, just at a glance I couldn't see the orifice tube. I'm guessing its in with the evaporator core?? I'll research it.. but it'd be nice if someone stumbling upon this thread could know where to find it. Thanks again for the advice!

Nitehawkjr

The orifice is at the coupling under the hood where the line goes into the evaporator from the condenser just right of the dryer.