So now what do I do?

[vacaville dave]

Hello All,

I just bought a 91 Explorer, and took it in to see what it would cost to get the ac fixed. They tell me I've got problems. They tried to see what was in the system, and it would not register on their machine. So a prior owner probably tried something other than R12 to charge a leaking system, and the shop suspects "black death". The shop tells me they can't pull the refrigerant out because they don't know what it is. Is there anything I can do? I've read many of the posts, so I have an idea about what's going on. I'm handy enough, but have no A/C experience.

Thanks.

 

[302Xplorer]

Go to another shop

 

[vacaville dave]

When I push the AC button, the compressor engages. On the freeway, I can feel a very slight drop in the air temp when I turn on the AC. Is there something quick and easy I can do to diagnose what the problem might be? How can I tell whether the system has R12 or if a prior owner converted to R134?

 

[vacaville dave]

Update

OK, here is an update on what I know:

1. It was converted from R12 to R134 sometime in the past (I think). The low side valve is the right size for a R134 refill can fitting.

2. The compressor kicks on when I push the AC button, and slightly cool air comes from the vents.

3. The low side metal AC lines are cool to the touch, and the line on the bottom of the compressor going to the condensor is hot.

4. I took it to a shop today, and they said their machine couldn't tell what refrigerant was in the system, so they couldn't (wouldn't) check it out further.

5. The compressor stays on full time when I turn on the AC. I let some refrigerant out (woops), and the compressor started to cycle every few seconds. I added some R134 from the can, and the compressor stopped cycling.

Any ideas?

 

[shamaal]

There were/are a number of R12 replacements on the market that met with varying kinds of commercial success. At one time I recall even propane was tried. perhaps you have the vestige of one of these types in the system. Glacier991 has a wider experience base with refrigerant recovery methods than I.

You mentioned there was a R134a fitting on the low side. Is there a similar type of quick connect (different size) on the high side? If it was a professional replacement there should be a R12/134a conversion sticker someplace. Perhaps it fell off.

Cheapest thing to do: sounds like a low charge, add a can of 134a refrigerant.

The next level of something I would do is replace the orifice and the accumulator, add 3oz oil to the accumulator, button it up and bring it to another shop for a charge. They will do an evacuation to remove air and moisture, hold for 15 minutes as a leak test, then add refrigerant. You'll need about 22 to 24 oz of R134a.

The next level I would do is replace the accumulator and orifice, get a set of gauges, and evacuate the system myself with a vacuum pump, test and fill.

Action depends upon risk that is acceptable and your financial state.

 

[vacaville dave]

Thanks Shamaal. I tried adding a can of R134, no luck. I try your other ideas next.

 

[Glacier991]

Hi, and welcome to the site.

At the temps we have been having here in the Sacramento/Vacaville area, the compressor should be cycling, not running continuously. I think instead of an undercharge you may have an overcharge. A gauge set would be helpful here. (Harbor Freight has one on sale for $40. - I love it when people use gauge sets and can do it right).

If you look at the thread about converting to 134 in the stickies you will see where I advise against "drop in" substitutes.... and one reason is that no shop will touch them. Your experience should serve as a warning to others.

I'd recommend you put a thermometer in the vent, and carefully release some vapor out the low pressure port on the accumulator side (use eye protection) until your compressor starts to cycle... watch the vent temps and continue until you start getting cold air about 15 - 20 degrees below ambient outside air temp.

ps. Ideally you would have the charge recovered, but since no one will do that you really have no choice. R-134 and its substitutes are far easier on the environment than R-12 was. That said, be advised that releasing refrigerant into the atmosphere is a federal offense. I can recover it for you, but you would need to buy your own tank to recover into. They run about $75 to $100 - and I have no idea what one would do with it once it we had put your refrigerant into it. (Get the drift here?)

 

[vacaville dave]

Thanks Glacier. I will get some gauges and report back.

 

[Brock94]

Glacier, it sounds like a prior DIYer just attached an R-134a fitting and dumped "who knows what" into the system. Isn't there a pretty good risk that the old mineral oil is all that is in there as well?

Maybe there has even been some R-12 in the mix to carry that oil around so the compressor didn't die-- but it seems to me it would be a good idea to flush the system out, dump the oil out of the compressor and replace everything with some new stuff. If he just fills this with 134a, he might have a compressor failure soon.

 

[vacaville dave]

I was thinking the same thing. I noticed that the hose from the compressor to the condensor is a Goodyear Galaxy. I checked, and I think this is a barrier hose that would have been put in during a switch to r134a. I have gauges and a vacuum pump now. What should I do first?

 

[vacaville dave]

I finally got my gauges, vacuum pump, and I'm ready to go. I just opened up the line into the evaporater to replace the orifice tube, and I can't find it! Should'nt it be visible, or at least shouldn't it be within reach of needle nose pliers? When I opened up the line, oil came out. I can put a small screwdriver into the line both ways without hitting anything. Where is the orifice?

 

[vacaville dave]

Sorry for all the posts, but I'm confused. I opened up the system to check the orifice tube (thinking black death), but to my surprise there was no orifice tube in place! I put one in, vacuumed pumped, and then started to charge. After I got about 14 ounces in, the compressor started to cycle right. The vent temps were down in the 50's (ambient 75 or so), and when the compressor was engaged the low side was 25 and the high side was about 225.

I stopped putting in refrigerant to let things level out. I was idling at 1500 rpm, sitting in the driver's seat watching vent temps, when I heard a "poof" from under the dash on the passenger side. The compressor stopped cycling (i.e. stayed on continuously), vent temps went immediately up, and the low side pressure went to 70 and the high side at 200. What happened? Why was there no orifice tube in the line? What do I do now?

 

[Brock94]

Those pressures sound like there's an obstruction-- probably at the orifice-- open her up again and take a look. You may want to just remove the evaporator and get a good look into it with a flashlight. Unlike many other vehicles, removing the evap is a pretty easy job with your truck.

That seems strange that there was no orifice in there-- I'm wondering if it somehow broke and got sucked into the evap.

 

[Glacier991]

Now we know the truth. I have never heard of this happening (O-tube being sucked into the evap), but here you are. The best news in all this is you can flush the system out right, replace the accumulator ... know the oil charge to put in and recharge it to spec. Piece of cake... just a tad pricey.

 

[vacaville dave]

I looked into the evap tube after I pulled the evap off. The orifice tube is there, all the way at the back. I'm waiting for new parts to arrive, then I get to put it back together. I'm hoping the issue was with the evaporater. Oh well, live and learn...

 

[Glacier991]

Keep us posted. Be sure and flush the system fully. I even recommend replacing the line with the "muffler" on it (return line from evap to compressor), as you cannot adequately flush the muffler. Good time to replace the accumulator as well.