A/C compressor oil capacity

Hey guys, 

Replacing compressor on my son's 04 Pontiac Vibe. New compressor says it has 5.0 onces of PAG 150 oil in it. Google is telling me different things regarding capacity. If I need to add oil, do I need to make sure it's PAG 150, and can I add it after it has been installed? 

You can add freon with lube in it, but you never really know how much you're adding.  Adding straight lube would require a purge and re-fill.

In theory, a pre-lubed compressor is good to go.  If the googles says 7 ounces total, you're probably just fine since the rest of the system has residual oil in it.  What type of compressor is it?  IIRC, it's a Sanden 508, right?

Also the kit I got from rock auto came with this part, but I can't figure out where it goes. Any ideas? 

In reply to Mazdax605 :

That looks like an expansion valve. 
Probably either located at where the ac lines go into the firewall, or on the evaporator core inside the car. 

Saron81 said:

In reply to Mazdax605 :

That looks like an expansion valve. 
Probably either located at where the ac lines go into the firewall, or on the evaporator core inside the car. 

It's not located where the lines go through the firewall like they were on my 04 Suburban. I don't know if I want to tear apart the dash to replace this part. 

Expansion valve on a Vibe should be accessible by taking out the glove box and evaporator if it follows normal Toyota logic but I haven't done a vibe in years.

If it ain't broke, don't fix it.  Try it without replacing the valve.  Worst case is you have to recover the freon, replace the valve, and recharge, but my guess is that it's fine.  When you recharge, post up your high and low numbers as well as ambient temp and it should show us how the expansion valve and condenser are working.

Per GM's official specification from GM Service Information: 

The footnote for the spec is that if more than 2.5oz is drained from the old compressor, then use that amount 

I would run it as-is.  I would be concerned if it called for 8 oz, but a little extra shouldn't hurt.  You might reduce your cooling by half a degree, but I wouldn't stress about it.

We usually used factory spec for oil in the compressor not knowing how much oil was scattered around the rest of the system, so we always had a little too much oil and never knew how much extra since we couldn't know what was hiding in the evaporator or condenser.

In reply to Mazdax605 :

I think the idea is that you'll never be able to flush that expansion valve out, so if you have catastrophic compressor failure that sends metal particles thru the system, it'll need replaced. 
Why are you replacing the compressor?

Saron81 said:

In reply to Mazdax605 :

I think the idea is that you'll never be able to flush that expansion valve out, so if you have catastrophic compressor failure that sends metal particles thru the system, it'll need replaced. 
Why are you replacing the compressor?

I bought the car from a friend a year or so ago. There were a few problems with it, most notably he said that the A/C compressor needed to be replaced according to his mechanic. I decided I'd buy a whole kit thinking that it probably needed more than just the compressor. 

Curtis73 (Forum Supporter) said:

I would run it as-is.  I would be concerned if it called for 8 oz, but a little extra shouldn't hurt.  You might reduce your cooling by half a degree, but I wouldn't stress about it.

We usually used factory spec for oil in the compressor not knowing how much oil was scattered around the rest of the system, so we always had a little too much oil and never knew how much extra since we couldn't know what was hiding in the evaporator or condenser.

The internet says the system capacity is 8 ounces, but I don't know if that's accurate. Should I have coated the o-rings in oil before installing them? 

In reply to Mazdax605 :

A little bit of on the o rings is good. 

sergio said:

In reply to Mazdax605 :

A little bit of on the o rings is good. 

Should I take apart the fittings I've put together without any oil, and oil them? 

Mazdax605 said:

Saron81 said:

In reply to Mazdax605 :

I think the idea is that you'll never be able to flush that expansion valve out, so if you have catastrophic compressor failure that sends metal particles thru the system, it'll need replaced. 
Why are you replacing the compressor?

I bought the car from a friend a year or so ago. There were a few problems with it, most notably he said that the A/C compressor needed to be replaced according to his mechanic. I decided I'd buy a whole kit thinking that it probably needed more than just the compressor. 

Always do a whole kit.  Accumulators are cheap and the old one is likely full of junk and the dessicant is likely spent.  Expansion valve is always a good idea but in your case it requires dash disassembly so try it first without.

There is the risk of the system being full of metal shavings, but not as common as people are usually afraid of.  An AC compressor wears out much like piston rings wear out... slowly.  The chances of big yucky metal shavings are slim.  When I flush an A/C system, I don't flush the evaporator or condenser.  It's nearly impossible to get much of any junk out of it and you risk dislodging sludge but leaving it there.  I basically flush lines and that's it.  If I suspect a really cruddy system, I'll replace the evaporator and condenser before I would flush it.

I say, do the compressor and accumulator and give it a shot.  If you have no air or poor air, then look into further diagnosis.

I don't see a need for oiling the rings if its already assembled.  It's mostly to make assembly easier without ripping the O-rings, but it's not like it's essential for sealing.

Curtis73 (Forum Supporter) said:

Mazdax605 said:

Saron81 said:

In reply to Mazdax605 :

I think the idea is that you'll never be able to flush that expansion valve out, so if you have catastrophic compressor failure that sends metal particles thru the system, it'll need replaced. 
Why are you replacing the compressor?

I bought the car from a friend a year or so ago. There were a few problems with it, most notably he said that the A/C compressor needed to be replaced according to his mechanic. I decided I'd buy a whole kit thinking that it probably needed more than just the compressor. 

Always do a whole kit.  Accumulators are cheap and the old one is likely full of junk and the dessicant is likely spent.  Expansion valve is always a good idea but in your case it requires dash disassembly so try it first without.

There is the risk of the system being full of metal shavings, but not as common as people are usually afraid of.  An AC compressor wears out much like piston rings wear out... slowly.  The chances of big yucky metal shavings are slim.  When I flush an A/C system, I don't flush the evaporator or condenser.  It's nearly impossible to get much of any junk out of it and you risk dislodging sludge but leaving it there.  I basically flush lines and that's it.  If I suspect a really cruddy system, I'll replace the evaporator and condenser before I would flush it.

I say, do the compressor and accumulator and give it a shot.  If you have no air or poor air, then look into further diagnosis.

Thanks Curtis. 

So you think I'm good with the 5 ounces in the new compressor, new condensor, drier thing that was attached to it, a vacuum down, and charge? Only thing I haven't connected is the lines to the compressor at this point. 

I personally think you'll be fine.  If you are worried about it, I think you can still get freon with lube in it.  Use that can first so you know if the can says "with 2oz of PAG" you know you're adding 2 oz.  Then fill the rest with straight R134.  Or, maybe put another ounce or two in before you connect the lines.

The oil in your system more or less goes along with the flow and keeps things lubed because there is a mist of oil with the freon.  Some will puddle in the compressor, but I think you'll be fine.

If I were doing it, I would do the compressor, accumulator can, vacuum, and recharge.  If I have flush fluid, I'll do the lines while they're apart.  R134 is cheap enough that I charge first.  If its cold and the high/low pressures are good I call it done.  If they aren't, I use the pressures and temps to figure out what might be additionally wrong.

I'm probably making the real A/C folks here cringe, but that's how I do it.

Do you need tips on charging?  I'm not the master and I have to look it up every time, but I do know some procedures that have helped me.

Curtis73 (Forum Supporter) said:

I personally think you'll be fine.  If you are worried about it, I think you can still get freon with lube in it.  Use that can first so you know if the can says "with 2oz of PAG" you know you're adding 2 oz.  Then fill the rest with straight R134.  Or, maybe put another ounce or two in before you connect the lines.

The oil in your system more or less goes along with the flow and keeps things lubed because there is a mist of oil with the freon.  Some will puddle in the compressor, but I think you'll be fine.

If I were doing it, I would do the compressor, accumulator can, vacuum, and recharge.  If I have flush fluid, I'll do the lines while they're apart.  R134 is cheap enough that I charge first.  If its cold and the high/low pressures are good I call it done.  If they aren't, I use the pressures and temps to figure out what might be additionally wrong.

I'm probably making the real A/C folks here cringe, but that's how I do it.

Do you need tips on charging?  I'm not the master and I have to look it up every time, but I do know some procedures that have helped me.

Yes, I need as much help as possible. 

Well, I'll tell you what I know.  As far as the actual amount of charge you'll use your gauges and the factory spec for how many lbs you put in.  If you flush with anything, make sure it's the right A/C flush stuff for two reasons; 1) it won't damage the rubbers in the hoses, and 2) it has an evaporation point that means it will all evaporate under vacuum.

When vacuuming, I like to hook up both the high and low sides.  For the initial vacuuming, I open the low side for the bulk of vacuuming.  Opening the high side (depending on the configuration) can sometimes suck lube out.  Vacuum it for a good long time.  If I flushed, I will sometimes close the high side valve and loosen the high side hose at the manifold until I hear a slow leak.  The vacuum will evaporate all the solvent but since it can't vacuum everything, allowing a little air to flow through it will purge it out.  Then reseal the hose and vacuum again.  You can't over-vacuum.

Mark the vacuum reading on both gauges, close both valves on the manifold, and turn off the vacuum pump.  Walk away and leave it for an hour or so.  There is an acceptable spec for how much the vacuum can drop over a certain time.  I shoot for zero leaks and usually get there.  If you come back and notice that the gauges have moved an unacceptable amount, check all your hose fittings and try again.

Once you have it vacuumed and sealed, Start the engine and turn the A/C system to the highest demand; recirculating (max), full cold, and high fan. Find some way of holding the throttle open to 1500-2000 rpm so that you're simulating actual driving conditions. Don't expect the compressor to kick on because the pressure switches aren't registering any pressure.  As you charge, it will start kicking on. Hook up the freon and start charging through the low side. Charging through the high side can introduce liquid freon directly into the compressor and that's not bueno. 

Folks have different ways of charging.  I turn the can upside-down because it's a little quicker.  This pushes liquid in as opposed to with the can upright pushing evaporated gas.  I control the speed of the charge with the manifold anyway.  Once you get close, you could turn it back to right side up.

The ending pressures and weight of freon are up to several factors including ambient temps and your location.  A Canadian car might take a wee bit more freon than a Florida car because of the average high temps for each region.  Youtube and others here should get you the finer points.  That should get you dialed in.  The big numbers you're looking for are published somewhere.  Your important things are the low and high numbers when the compressor is on. When it kicks on, the low side should drop and the high side should rise.  Low side should settle in around 20-30 psi.  The high side should settle in near 250 psi.  The general rule is - twice ambient temperature plus 50.  So if it's 90 outside, you're looking for 230 psi.  The high side limit switch usually cuts things off around 300 psi which leaves room for revving up past your test RPMs.  If you gun it and get to 3500 RPM and lose A/C, you know you've likely overcharged or you have some kind of blockage.

This website has a good tutorial on how to read the gauges to figure out what's wrong if something doesn't end up quite right.

Keep track of your pressures and how much freon you put in.  That way if you come back here with questions, you'll be armed with all the answers to our potential questions.

Like I said, I'm no expert, I've just done it a dozen times or so using advice from here and the googles.  If anything I wrote here isn't spot on, someone please chime in and slap me.

System all connected. Fixed a bunch of little annoying things like the plastic under trays were all held up with ty-wraps. The car was clearly in a fender bender which I knew, but it was hastily put back together. Now it's time to figure out how to vacuum the system down, and then attempt to charge it.