brickwal92tt

I have an A/C question for my inlaws 96 Lumina.

The a/c wasn't cooling as cold as it should for a week or two before it quit.

While driving to church one Sunday, the a/c died, but once we arrived and turned off the car, I smelled burning rubber. Looks like the compressor overheated and was burning the belt.

That has never happened again, thankfully! The air blows hot now, the compressor runs/engages still but makes a grinding noise when it does. I haven't checked for movement yet on the pulley.

Now my questions: What happened?

Will replacing the clutch/pulley fix it? It engages, so I'm sure the stator functions.

I'm assuming the grinding noise is caused by the worn bearing/pulley?

I also assume it will need a recharge if that fixed it?

I'd like to avoid opening up the system, thus not taking the compressor off. Their mechanic quoted them $1,200!!! The car just isn't worth it even though it has only 100k miles.

If I can easily fix it myself, then it makes sense to do so.



I'd like to confirm the compressor wasn't damaged before I try replacing parts for it...

Thank you!

oilcanhenry

Well, you found the right man for the job. I specialized in automotive air-conditioning long ago, before I became a commercial Driver. Unfortunately, I do have some very bad news, but the GM V5 A/C compressor seized up/busted on you and is gone. You lost pressure/refrigerant and the lubricating oil to the compressor and it all has to have both flowing smoothly through the system to operate correctly, at proper lubricant and pressure levels. After all your 1996 Lumina is very old now, and nothing lasts forever, not even Chevrolet's

Either your low-pressure switch might have gone bad, as it would have shut down the magnetic clutch that drives the compressor, when the pressures got too low, but it didn't,( not very likely) or your compressor was going bad and locked up,
even when the pressures are in the normal range, thus the low-pressure switch didn't know to shut the magnetic-clutch down, which means your serpentine belt was running over the pulley grooves, making that rubber smell you mentioned. It will need replacement too.

It gets worse, I am afraid. Since I know your A/C compressor is wasted, its likely that lots of particles of metal and possibly other materials are now in your A/C system, and you will have to tear it down and replace lots of parts including the A/C compressor and the receiver/drier/accumulator ( the big aluminum can looking device likely on your fender, with inlet and outlet fittings) as well as the orifice tube, which is likely full of all kinds of junk now.

The system will need to be flushed out good, including the evaporator (the small radiator-looking device inside your climate control box that puts out the cold air in your cabin), Thankfully you probably wont need to replace your condenser (the radiator-looking device in front of your radiator) as back then in the 90's, the cooling tubes were larger then they are now on more modern cars that use much thinner tubes,otherwise you'd need to replace that as well, as the new cheap condensers don't flush-out well at all.

After flushing, all the new parts will need to be installed, of course. The AC Delco/Delphi Harrison V5 air conditioning compressor the Lumina uses will run over $200 dollars or more, depending on rebuilt or new, and you'll need 8 ounces of PAG 150 oil for the compressor, but a little extra ounce or two, won't hurt at all, after a flush. The receiver/drier/accumulator will be around $50 bucks and the orifice tube is cheap; under 10 bucks. Then you'll need to evacuate all of the atmo from the system for at least a half-hour (1 hour is even better) with an A/C vacuum pump, about $130-150 bucks at Harbor Freight.

You'll likely have seals/o-rings that are old, so you simply soak the new ones with PAG oil and tighten down the fittings, before you vacuum the system down to -30 PSI and it holds there. Once all of that is done, you'll likely need a gauge set (I think Harbor Freight has some for $30-40 bucks) for the high and low readings of the R-134A refrigerant to be added properly to the A/C system.

You will need about 32 ounces of R-134A refrigerant, assuming that you have front air-conditioning only on your 1996 Chevy Lumina. The low side inlet valve is on the larger AC line and the high side connector is on the smaller line. Hook it up making sure all the valves are closed, then open the first can of R-134A. I always allow some of the R134A to blow atmo out to purge the lines of air on high and low side, before you connect them, as you don't want any air in your AC system, and it will blow as cold as possible when you are done, with no air in the system.

With everything tightened down good, and the magnetic clutch or low-pressure switch bypassed, so the magnetic clutch will engage and be able to pump refrigerant, you can open the can all the way back up and turn on the motor with the AC setting all the way to the coldest setting, then open up the low-side valve on the set slowly, so that nothing internal is damaged when the R-134A and the PAG-150 start circulating through the A/C system.

I like to add some R-134A to the low-side first to get the oil flowing and R-134A in the system, and then turn on the motor to recharge the system to capacity. Depending on factors like ambient temperatures, humidity and such the pressures will vary some. but 35-45 PSI on the low-side and 170 to 225 on the high side is normal. It can be more or less then that somewhat, but I use a thermometer in the vent to get it to 38-42 degrees Fahrenheit at the outer outlet vents on the dash with the interior control fan on high and the A/C dial on full-cold, not max or recirculate (which the "max" A/C control setting turns on, automatically).

Don't forget to disconnect the bypassing you did for the compressor to start turning, which it will on it's own when the low-pressure switch senses enough pressure and always wear gloves and eye-protection. R-134A is not toxic to humans; neither was R-12 Freon, but it can freeze your digits, if you don't have gloves and it happens to spring a leak or a can ever ruptures.

Good luck to you!

brickwal92tt

Oilcanhenry, WOW, I couldn't have asked for a better answer! That's exactly what I was looking for and more. Thank you so much! What you've listed sounds within my neighbor and my skill range. He has the a/c pump/gauges and has helped me replace a condenser on my Expedition. Thankfully the required parts sound within range of what my inlaws would spend. I'm sure my neighbor and I will be referring to your reply as our shop manual many times during the repair. I'll keep you posted on how it goes, hopefully within the next few weeks....

P.S. You don't happen to live near the Tampa area?..... ; )

oilcanhenry

Glad I could help you out, brickwal92tt. That's really great that your neighbor has lots of the equipment you'll need, so you don't have to buy any more devices to get your air-conditioning system up and running, or I should say your in-laws Lumina's A/C system. I live on the west coast of the US, so nowhere near Florida, but I would like you to keep me posted about how it goes with your repairs. Any other questions I can and will answer. Automotive air-conditioning and old carburetors are my speciality.