1992 Ford Explorer XLT Compressor issues

[overripeturnip]

Hey guys, I've been trying to get my AC working today. The previous owner claimed to have converted it to R134a and, when I bought it from him, said the AC had worked for a while when he last recharged it but suspected one of the lines was weeping. I bought some new 4seasons lines, an accumulator and a orifice tube expecting to find the system already empty. To my surprise, I hooked up my AC gauges and discovered the LP valve read 80psi. It seems the previous owner only fitted a R134a adaptor to the low side, and so I was unable to do any 'dynamic' readings straight away. I fired the old girl up and the compressor clutch failed to engage. After a lot of poking about jumping the low pressure connector and the clutch connector itself to no avail, I checked the clutch air gap. It was measuring around 0.060". I removed a shim and managed to bring this within spec (down to around 0.025"), which started the clutch engaging and I thought this was gonna be the world's easiest fix. A quick trip to O'Reilly's produced a HP valve adaptor and I was finally able to hook up my gauges for some proper diagnosis.



I'm pretty sure the compressor is done for. The LP side seems far too high and isn't cycling. I had everything on max (Max A/C + full blower), but both gauges sat at roughly the same pressure the whole time. I tried to show in the video the sounds coming from the compressor itself. It's making quite a racket. Even as I'm typing this, I realise I've pretty much convinced myself to replace it, but I would appreciate a second opinion from somebody a little more experienced. I just don't want to throw more money at this if the compressor's not the problem.

 

[Maniak]

The video is too dark for me to see the front of the compressor... So I'm going to assume it is really engaging. Since you are getting no suction or pressure when the compressor turns on I'd say you have a bad compressor. If the compressor let go you probably have quite a bit of crap caught in the screen on the orifice tube so when you change the compressor and evaporator I'd change the orifice tube too.

~Mark

 

[overripeturnip]

Hey Mark, thanks for your thoughts. I wasn't planning on changing the evaporator or the condenser since I figure the big old inline filter positioned right after the compressor probably caught the majority of the shrapnel. I was going to replace that line (along with the filter) and flush everything out thoroughly. I also have a new orifice tube waiting to go in while I'm at it. My only other question is regarding the proper amount of refrigerant to charge the system with. It was originally designed for R12, so how much R134a should it require? I was looking at NAPA's recommendations for a '94 which is 36oz of R134a and 7oz of PAG46. I'm guessing this would be a good starting point since it must be essentially the same system as my '92.

 

[Maniak]

Hey Mark, thanks for your thoughts. I wasn't planning on changing the evaporator or the condenser since I figure the big old inline filter positioned right after the compressor probably caught the majority of the shrapnel. I was going to replace that line (along with the filter) and flush everything out thoroughly. I also have a new orifice tube waiting to go in while I'm at it. My only other question is regarding the proper amount of refrigerant to charge the system with. It was originally designed for R12, so how much R134a should it require? I was looking at NAPA's recommendations for a '94 which is 36oz of R134a and 7oz of PAG46. I'm guessing this would be a good starting point since it must be essentially the same system as my '92.

I think that will be too much.... The 1991-1993 capacity is 32 ounces of r-12 and typically you run a little less when converting.

Over the years I've had a few things replaced, like the evaporator when I accidentally hit it with a grinder and I've noticed around 28 ounces seems to be where I get the best cooling. I'm also running a variable orifice tube to help the idle cooling.

I'm hoping to rebuilt the a/c this year but I'll need to replace everything since the system is full of black death. It's bad enough that I have to replace the orifice tube yearly. I can get the entire system including evaporator and condenser for right around $500.. And that comes with a lifetime warranty... Soo.. check for black death (black goo) in the lines when you take them apart.

~Mark

 

[overripeturnip]

Thanks, Mark. I've been searching everywhere for a recommended charge after converting to R134a. Does the 7oz of PAG46 oil sound reasonable? What does the black goo signify? I did look at those variable orifices but didn't understand what the benefit was supposed to be so opted for a fixed Motorcraft one instead.

 

[Maniak]

Thanks, Mark. I've been searching everywhere for a recommended charge after converting to R134a. Does the 7oz of PAG46 oil sound reasonable? What does the black goo signify? I did look at those variable orifices but didn't understand what the benefit was supposed to be so opted for a fixed Motorcraft one instead.

7 ounces sounds right.. It's what I see for the oil capacity on the 91-93 and for the 94 system.

The black goo (aka black death) is crap from the compressor seals mixed with the refrigerant/oil. It's pretty much impossible to flush out.. Here's a page that explains it... http://www.aircondition.com/tech/questions/15/What-is-Black-Death?

Here's a shot of my orifice tube full of black death.

Black Death on a Variable Orifice Tube by maniak_az, on Flickr

As for the VOR... It's basically trying to get you the best flow/pressure differential at idle and on the freeway. This page explains how it works better than I can. http://www.freeasestudyguides.com/fixed-and-variable-orifice-tube.html

~Mark