AC problem

[ronnidonni]

I found this forum looking for 98 Ranger evaporators.
Here's my problem. My Ranger lost all of the AC cooling capability since last summer, so I took it to the mechanic to see if it needed an R-134 refill.
The tube going into the evaporator was cold and the tube coming out was warm and the compressor cycled constantly. I picked up an evaportor at a junk yard a couple of days later for him to put in but we couldn't use it, the tube where the valve is was bent. So we blew out the existing one in reverse and filled the system and it all worked fine. Note thought, when he pumped out the system it never did get down to 22 lbs. He figured it had a leak but couldn't find it with his wand. Then we put the refrig back in and at 1.8 lbs (what the book says it's supposed to have). The compressor continued to cycle and the air didn't cool. He put more refrig in and the system started to work correctly. Incidentally, the first visit we replace the high pressure and low pressure valves, that had leakage around them.
That was 10 days ago. Now my AC is warm again and I notice there is hardly any condensation dripping when I park it. Looking at the picture tells me the "blanket" on top of the accumulator is sort of just sticking up and I haven't looked at it for rust yet. Just found this site.
Any ideas? I spent a good chunk of change in the last 2 weeks and am right back where I started.

 

[shamaal]

If you can't vacuum the system, it won't hold a charge.
A search on A/C leak in this forum will bring up a night's reading. Common leak points are:
Fittings (Make sure you have the caps on)
O Rings on the back of the compressor
Rusted accumulator (hidden by blanket)
Fittings (Orifice)
Condensor (Welds)
Compressor (oil spray line under hood)
Evaporator

It's good practice to replace the accumulator once the system has been opened

Common methods of looking for leaks are:
Sniffer
Presence of oil
Press system with some Freon and use soapy water on joints (This really works)
Press system with Freon with UV dye (also works)

I believe there is an EPA sticker next to the hood latch that tells the correct charge.

Read the forums, once leak is found, return the low and high press readings and ambient and vent temperatures.

This is a vast topic, feel free to ask questions. I personally am puzzled about the attempted evaporator change, the symptoms sounded like a low charge as opposed to a bad accumulator.

 

[BrooklynBay]

If you are opening up the system, this would be a good time to replace the orifice tube. Shamaal has a picture of his that was clogged with "black death" fragments from the compressor.

 

[BrooklynBay]

Here is that picture:

 

[ronnidonni]

Thanks guys. I recognize the Black Death photo as this is pretty much what mine looked like when he replaced it on the first visit. Obviously this part has been replaced, but what causes the particles? The mechanic said it was from the compressor breaking down. My truck has 122k on it, and he did put in about a pound 2 years ago. This time round it seemed logical that it would need a pound added but that doesn't seem to be the fix.
Yeah Shamaal, I believe a low charge was the original culprit. His guage read the correct about of pressure, but it still wasn't working. I'm thinking his guages are off...I might go by there tomorrow and have him throw some more refrig in and check again for leaks. The bummer is that now I really need the AC. Crap...

 

[BrooklynBay]

R12, and R134A gauges are calibrated differently. Hopefully he used the correct gauge.

 

[BrooklynBay]

Check this link. It has Shamaal's explaination of what causes black death: http://www.explorerforum.com/forums/showpost.php?p=1467296&postcount=9

 

[rookieshooter]

In a residentail AC black death can also be the insulation around the wires in the compressor start breaking down and contanimate the whole system via the refregerant. I would suppose the same thing in an auto AC system. Generally the windings get too hot and that is what breaks down the wire insulation. I would use a gauge called a magnometer to help check the conditions of the windings.

 

[ronnidonni]

Check this link. It has Shamaal's explaination of what causes black death: http://www.explorerforum.com/forums/showpost.php?p=1467296&postcount=9

This is a scary thought. Seems the best thing to do is replace every component. That would be crazy expensive I think. I think I'll go by a shop the specializes in AC today and see what they say. I'm in too deep now to just give up. 'sides, a summer without AC is nuts.

 

[ronnidonni]

Ok, continuing the saga.... I went to a different mechanic yesterday. This guy as all the right equipment and so forth. My system was only down about .3 pounds, however we discovered another problem. BTW, he vacuumed the system and added dye when he re-filled it. I'm supposed to go back in a week or so, or if the air starts blowing not cold before that.
The other problem is the valve that lets water into the heater core. It sits on top of the engine and is controlled by vacuum pressure. There is vacuum up to the tube that controls the valve. He says it could be the temp control switch, or a broken or kinked hose under the dash. Anyone have any thoughts on that? Apparently hot air was still coming into the cabin via the heater core. He wired the valve closed for now so I can't turn on the heat.

 

[BrooklynBay]

If the valve is bad, why didn't he just replace it instead of messing up some wiring?

 

[ronnidonni]

If the valve is bad, why didn't he just replace it instead of messing up some wiring?

Well, we don't know the valve is bad. Somewhere along the line the vacuum isn't getting to the valve. Most likely the valve is ok, it worked just fine recently. He didn't mess up any wiring. The term I wanted yesterday but coudn't think of was wire tye. He used a wire tye to keep the valve closed. Both heater hoses were extrememly hot yesterday, meaning that water is getting into the heater core when I have the temp selector on cold. That valve should keep any water from getting into the heater core.
Make any sense?

Thanks though.....

 

[shamaal]

I can't speak to the ranger, on my Navajo, there is a MAX A/C setting on the temp control. When in this setting the vacuum is routed to a damper that recirculates air in the cabin. I've read that on newer models the MAX A/C vacuum also goes to a vacuum valve for the heater. These lines are extremely brittle. The damper is behind the glovebox and makes a whump sound when closing. the tubing connections are on the passenger side behind the right side panel.
If yo do have a broken line going up to the valve you would have a vacuum leak. If you take off the vacuum connector at the valve, does it suck?
If not, the problem is between the removed connector, the environmental controls and the manifold. The Mazda Navajo is similar to the Explorer, the Explorer is similar to the Ranger. Of course rounding errors may mean this is not applicable.
Early Navajos and Explorers have a vacuum reservoir (cannister) next to the evaporator on the passenger side. See picture. Does yur ranger also?

 

[BrooklynBay]

One thing I was thinking about was if somebody added R134A to a system that was charged with R12. Would this cause some sort of thermal breakdown, and create the black death contamination problem?