AC compressor port on back left? Leaking from snap ring - what is it?

I found a leak on my compressor. This port off the back side of the compressor itself is slowly hissing. The compressor works and keeps the interior cool but that port leaks down to the point where the clutch won't lock anymore. Can I reseal what is there? It looks like a snap ring holding the entire assembly in - what is that and please tell me it can be resealed!

That's the high pressure switch, it's meant to kick your system into recirculate mode when the compressor head pressure gets too high. The switch body itself may be leaking, or the O-ring that seals it could possibly be bad.

Obviously, you need to evacuate the system to replace it (it's a wide-open port into the compressor's inner workings) and yes, that's a snap ring retaining it. Pay close attention to the color of the plastic on the connector end before you remove it, so you get the correct replacement. There are new colors with a small sheet in the box that tell you what old color switches they are meant to replace. Refer back to your pic on the color as the switches usually crumble to pieces with the force needed to pull the old one out.

Richard

If you are inclined, its pretty easy to reseal the whole unit once You have it evac’d. No special tools other than the clutch puller. there was a YouTube by “centurybob” which I found helpful.

Thanks folks. Well I guess I am going to bite the bullet and get a reman pump and a new dryer. Where is the orifice tube on these trucks - I should change that too. Thanks again.

1992? It'll be up front in the lower tube to the condenser, where you see the 'swollen' part of the tube just past the fitting (this change happened during 1991 model year; earlier trucks had them at the evap connection.) Be careful cracking the coupling nuts loose. I prefer to use a pair of quality adjustable wrenches here, tightened as much as possible, and clocked just apart enough that I can squeeze them together to crack the nut loose. It's easy to round the flats off or twist the line.

Richard

Is your compressor making noise? I would suggest resealing what you have if it is functioning properly. It has been nearly 20 years since I was doing A/C professionally, but reman compressors had much higher failure rates than new or OE did back then. I can’t imagine that has changed much since then. Not to mention there is a lot more work to properly replacing a compressor and associated components vs resealing that leak.

someotherguy said:

That's the high pressure switch, it's meant to kick your system into recirculate mode when the compressor head pressure gets too high. The switch body itself may be leaking, or the O-ring that seals it could possibly be bad.

Obviously, you need to evacuate the system to replace it (it's a wide-open port into the compressor's inner workings) and yes, that's a snap ring retaining it. Pay close attention to the color of the plastic on the connector end before you remove it, so you get the correct replacement. There are new colors with a small sheet in the box that tell you what old color switches they are meant to replace. Refer back to your pic on the color as the switches usually crumble to pieces with the force needed to pull the old one out.

Richard

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I just realized that you said that is a switch. It did not have any wires attached to it. In my picture I see a loose looking connector with 2 wires going to it - does that look like the right connectors? I know it is leaking from around the switch as I checked but could also be leaking through the body or connectors. I think it should be completely replaced. Do you think I could replace that switch on the truck (not in a position to really redo the whole compressor now so I would be willing to replace just that switch for now)?

Did someone say it's a 1992? If so it was an R12 system (I see it says R12 on the label on the compressor) and someone... converted it? Or did they? @454C2500, this is stuff you need to tell us.

If it was an R12 converted to R134a, and the condenser wasn't replaced with a more "efficient" condenser (along some other parts too, orifice tube, R/D), the high-side pressures can get, well, atypically high because the condenser can't shed the heat well enough.

Might this be a cause for the leak on that switch?

Anybody else got thoughts on this?

someotherguy said:

Be careful cracking the coupling nuts loose. I prefer to use a pair of quality adjustable wrenches here, tightened as much as possible, and clocked just apart enough that I can squeeze them together to crack the nut loose. It's easy to round the flats off or twist the line.

Click to expand...

Good advice here. You need to use a backup wrench, as he described.

TOO, you may need to use a flare nut wrench(es) / flare nut crowfoot(s) to prevent rounding the corners. These are aluminum fittings, easily deformed, and can in some cases be impossible to separate.

1998_K1500_Sub said:

If it was an R12 converted to R134a, and the condenser wasn't replaced with a more "efficient" condenser (along some other parts too, orifice tube, R/D), the high-side pressures can get, well, atypically high because the condenser can't shed the heat well enough.

Might this be a cause for the leak on that switch?

Anybody else got thoughts on this?

Click to expand...

I had that issue on my 88. I replaced the orifice tube with one from a 99+ (ADO-15-5378 at Summit Racing), a Spectra Premium parallel flow condenser, an accumulator/drier, and a Murry high pressure switch (35961 from O'Reilly's) which goes on under 200 PSI and off @ 430. This HP switch blew out of the compressor (sounded like a shotgun) when I started the engine on a hot day after driving for a while because, the older R12 systems used a 1 wire switch (NLA) and were wired to close the recirculating air door to help reduce pressures with warmer air (IMO a stupid design). It did not shut off the compressor. So, one ruined compressor later, I wired the HP switch in series with the LP cycling switch and have been running it for a couple years now with nice cold air and no issues

I wound up reusing the clutch off that compressor because the new NAPA compressor I got smoked its clutch within a week due to its air gap being too wide (~0.080"), it s/b 0.020" - 0.030" IIRC. YMMV