AC issues (1 Viewer)

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OK, I am stumped. I was fixed a leaky O-ring in the AC on my LC 100. I pulled vacuum on my AC system with a vac pump.

The vac pump failed, and all the dinosaur oil from the vac pump sump got sucked into my AC from the (good) vacuum. I estimate it was a couple ounces.

So I took all the lines apart, cleaned them out, drained the sump of the compressor, filled it with the right amount of PAG 46 oil, new drier, and buttoned it all up. Put in 39 oz. of Freon, but noticed the low side pressures were very high (60psi). Figured the bad oil mixed with the PAG46 and was gooping up the expansion valve. Pulled the evap core, replaced core, expansion valve, drier bag.

So pulled another vacuum, and... STILL low side is too high after I put 39oz. in, I was hitting 60psi low side (150psi high, but I measured on a half a charge. I'll measure on the full charge.)

I'm kind of stuck as to where to go from here. Anyone have any ideas???
 
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Drove in to work, AC blows much colder at speed... Low pressure line has condensation on it, so it is getting cold. Starting to think maybe my condenser fan isn't coming on.
 
OK, I am stumped. I was fixed a leaky O-ring in the AC on my LC 100. I pulled vacuum on my AC system with a vac pump.

The vac pump failed, and all the dinosaur oil from the vac pump sump got sucked into my AC from the (good) vacuum. I estimate it was a couple ounces.

So I took all the lines apart, cleaned them out, drained the sump of the compressor, filled it with the right amount of PAG 46 oil, new drier, and buttoned it all up. Put in 39 oz. of Freon, but noticed the low side pressures were very high (60psi). Figured the bad oil mixed with the PAG46 and was gooping up the expansion valve. Pulled the evap core, replaced core, expansion valve, drier bag.

So pulled another vacuum, and... STILL low side is too high after I put 39oz. in, I was hitting 60psi low side (150psi high, but I measured on a half a charge. I'll measure on the full charge.)

I'm kind of stuck as to where to go from here. Anyone have any ideas???

Bummer.

Chances are excellent you have Vac Pump oil in your condenser. All lines would need to 'flushed' (if that is what you mean by cleaned), desiccant bag replaced, Condenser blown out, Evaporator replaced, TXV cleaned.

If your TXV were clogged up you would have a low, low side pressure (not high)...so that wasn't the problem.

When you added PAG 46 to your compressor...how much did you add (8 oz.)?

Your refrigerant charge is correct...but any pressure readings taken are meaningless unless the full charge is in the system.

So if you have a full 39 ozs. in it now...then yes, take a new reading and let us know the high and low side pressures and the ambient temp at the time.

Make sure your fan clutch is working correctly and IF you have a condenser fan...note if it is coming on or not (it won't until a certain pressure is reached).
 
Bummer.

Chances are excellent you have Vac Pump oil in your condenser. All lines would need to 'flushed' (if that is what you mean by cleaned), desiccant bag replaced, Condenser blown out, Evaporator replaced, TXV cleaned.

If your TXV were clogged up you would have a low, low side pressure (not high)...so that wasn't the problem.

When you added PAG 46 to your compressor...how much did you add (8 oz.)?

Your refrigerant charge is correct...but any pressure readings taken are meaningless unless the full charge is in the system.

So if you have a full 39 ozs. in it now...then yes, take a new reading and let us know the high and low side pressures and the ambient temp at the time.

Make sure your fan clutch is working correctly and IF you have a condenser fan...note if it is coming on or not (it won't until a certain pressure is reached).
I broke all the connections and blew out the lines until nothing came out of the hoses. I made sure that the path for the air would not drive the oil inwards more, only out toward an open hose end. Since a couple of the hoses have muffler sections in them, I did not want to use a solvent for cleaning them.

Since the AC was not run after the vac pump oil got sucked in, the dino oil collected in three low spots - the bend under the low pressure port, the bend where the high line goes through the radiator support, and in the compressor. It did not get into the condenser then, it all collected in the line. So I got all of it but the compressor, which I pulled and drained upside down over a couple days, turning by hand every now and then to get as much oil out as I could- I didn't want to use solvent in there.

Since the compressor holds 8 ounces, and about 30-50% is supposed to stay in it, I took a SWAG guess and put 2.5oz in the compressor, and 40CCs in the evap core. I replaced the TXV when I was replacing the evap core because it was cheap, and I was taking it out anyway. I have changed out the drier bag twice, the last one was only in there for a few days, but it looked like it collected up what I am hoping is much of the oil. There just wasn't that much oil that went in.

So yes, there is certainly some miniscule residue of dino oil in the system somewhere. It would cost a grand worth of hoses and miscellaneous stuff, at least, to be sure it was 100% free of oil. So with a couple times taking things apart and blowing air through the lines, new evap core, couple of drier bags... I don't know. Hoping I got it, I guess...

Fan clutch is new... But at no time today did I hear the condenser fan come on, even after it was up to temp and idling. Going to test the fan and relay when I get home, and see if the high side pressures are good enough for the switch to energize the relay.

Thanks!!!!
 
I broke all the connections and blew out the lines until nothing came out of the hoses. I made sure that the path for the air would not drive the oil inwards more, only out toward an open hose end. Since a couple of the hoses have muffler sections in them, I did not want to use a solvent for cleaning them.

When you do this be sure (where possible) to block the exit (hold your thumb over it) to let pressure build up, then release it. If you aren't seeing a 'mist' coming out the end...then you aren't getting much out. If you simply blow air through the lines (unrestricted) you are leaving a lot behind.

Since the AC was not run after the vac pump oil got sucked in, the dino oil collected in three low spots - the bend under the low pressure port, the bend where the high line goes through the radiator support, and in the compressor. It did not get into the condenser then, it all collected in the line.

Maybe. IF you had both high and low side lines open to pull the vacuum (as you should) when the pump failed.... the oil would be drawn in equally from both directions. Now...it might indeed collect mostly in low spots...but no guarantee it didn't get go farther than you think. Did you use actual Vacuum Pump Oil in the pump (very important)? You used the term 'dino oil' more than once (as in automotive engine oil). Pump oil is Mineral Oil that has gone through a distillation process.

So I got all of it but the compressor, which I pulled and drained upside down over a couple days, turning by hand every now and then to get as much oil out as I could- I didn't want to use solvent in there.

^^^^ Good move.

Since the compressor holds 8 ounces, and about 30-50% is supposed to stay in it, I took a SWAG guess and put 2.5oz in the compressor, and 40CCs in the evap core.

Correct to add 40cc (1.35 fl. ozs) when replacing an evaporator (this will be a portion of the total 8 ozs.) The condenser also receives/holds about the same amount. The drier will hold varying amounts of oil/refrigerant depending on heat load/demand.

You don't want less than 8 ozs. PAG-46 (total) in the system...or it will effect the longevity of the compressor, but we also don't want too much oil (ounce or two over) because it results in diminished cooling. And in NO circumstance do we want contaminants (incompatible oils, moisture, etc) in the system.


I replaced the TXV when I was replacing the evap core because it was cheap, and I was taking it out anyway.

Good insurance. Aside from the compressor...it has the only moving parts in the front A/C system.


I have changed out the drier bag twice, the last one was only in there for a few days, but it looked like it collected up what I am hoping is much of the oil. There just wasn't that much oil that went in.

I'm not concerned at this point with the amount of oil that got sucked in...but how it might react (or not) with the PAG or refrigerant.

So yes, there is certainly some miniscule residue of dino oil in the system somewhere. It would cost a grand worth of hoses and miscellaneous stuff, at least, to be sure it was 100% free of oil. So with a couple times taking things apart and blowing air through the lines, new evap core, couple of drier bags... I don't know. Hoping I got it, I guess...

We will see. Hopefully.

Fan clutch is new... But at no time today did I hear the condenser fan come on, even after it was up to temp and idling. Going to test the fan and relay when I get home, and see if the high side pressures are good enough for the switch to energize the relay.

Good. Fan clutch is very important....good move. Your condenser fan (if relay and trinary switch are working correctly) should come ON when high side pressure reaches about 220psi and go OFF when the pressures decreases to about 180psi. If you don't adequate air flow through the condenser...you will have high pressure (high and low).

Thanks!!!!

Da Nada..........let us know what you find.

^^^^^
Expand for replies.
 
^^^^^
Expand for replies.
I used Lowe's Kobalt-branded air compressor oil. Bottle did not say what it was, actually, and I could not find the MSDS sheet for it or anything. I am going on worst-case assumption. However, all residue I blew out (blocking the other open outlets) did not appear to have any thickening, like I'd expect mixing Dino and PAG oil. Just don't know
 
I used Lowe's Kobalt-branded air compressor oil. Bottle did not say what it was, actually, and I could not find the MSDS sheet for it or anything. I am going on worst-case assumption. However, all residue I blew out (blocking the other open outlets) did not appear to have any thickening, like I'd expect mixing Dino and PAG oil. Just don't know

OK, wrong oil.

Air compressor oil is a lubricant for the moving parts of a compressor. Vacuum Pump Oil is Mineral Oil that is specially distilled to have a low Vapor Pressure. It is designed to readily accept and absorb moisture and is necessary to achieve a good, deep vacuum.

Don't know where that leaves you.
 
Well, wouldn't have been a problem if the stupid pump hadn't failed. :-(

Ambient temp 80 degrees. Low side 55, high side stays at 190, even at idle, when hot. Maybe I just under-estimated how much PAG oil was in the system before I opened it up and blew it all out, and didn't put enough back in? Crap, this is annoying.
 
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Well, wouldn't have been a problem if the stupid pump hadn't failed. :-(

Ambient temp 80 degrees. Low side 55, high side stays at 190, even at idle, when hot. Only thing that I know that could cause that is maybe a bad reed valve in the compressor is leaking pressure back into the low side? Crap, this is annoying.

Yes, unfortunate about the pump.

But you've done about all you can to mitigate the circumstance.

High side pressure is about right. Low side is still high a good 20 psi.

Possible causes are TXV stuck open or reed valve in compressor damaged (they are a stack of plates) or worn pistons in compressor. What kind of vent temps are you getting?
 
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