You put air in the system?

 

Yes as many do when empty to check for leaks. Pretty hard to test with 0 pressure in system and putting freon in when you don't know the extent of leak is 1) bad for the environment and 2) a waste of money. It will be vacuumed dry anyway.

My question is about the compressor oil.

 

Most techs use nitrogen, not air.
No need for oil.

 

Being a DIY guy buying a tank is expensive since I have no other use for nitrogen. I never have water in my air compressor tank due to the setup I have between the air compressor pump and tank. I also have 2 air dryers on output since I do some car painting.

Thanks for answering the oil question!

 

I'd just install a can of freon with the dye already in it and get the black light out.

 

So the standard oil charge is 3oz. Now, you can guess if there is oil left in the system.

Hint, the AC oil is designed to mix with the freon... no freon, no lube...

I would add the lube before running again.

 

Make sure to check the schrader valves and be sure they seal when the gauges are removed.

 

I have new valve cores but forgot to check that with manifold connectors removed, thanks! It's a slow leak so prime suspects.

Per Google AI:
Generally you should not add oil to an air conditioner that has had a leak unless you are replacing a component or have a large leak that has blown out oil. Adding too much oil can cause compressor damage or reduce cooling efficiency.

 

please stop quoting google AI... it's wrong at least 50% of the time...

this time it's accurate, but you have mis-understood the situation...

the system is EMPTY, no freon, no oil...

the AI says don't add more oil - but leaves out the part "assuming that most of the oil is still in the system"...

Also, the AI has OLD information, modern oil is miscible with the freon (i.e. it mixes), so if you lose freon, you lose oil.

Suggestion: if you know what you are talking about, contribute, if you don't please don't quote an inexperienced idiot software program.

 

Suggestion: if you know what you are talking about, contribute, if you don't please don't quote an inexperienced idiot software program.

Please, no personal attacks or put downs on the forum. You may cite correct information, and the source of that info.

 

Freon evaporates quickly. Oil does not. If the oil leaked out, there would be oily residue present were the leak is. If no oily residue anywhere, the oil did not leak out.

 

I was insulting the Google AI.... read carefully please... "inexperienced idiot software program"

also, if you have a leak, the oil that is mixed with the freon goes with it.... I don't know how many times it takes to stress this... please google it without AI

also since Freon is a solvent in many ways, you would not necessarily have an oily residue, in fact you never hear of this, i.e. a system with a slow leak and spotting the leak with a residue...

this is clearly why there are dyes and other ways to spot a leak...

so, your statements fly in the face of the facts...

 

also since Freon is a solvent in many ways, you would not necessarily have an oily residue, in fact you never hear of this, i.e. a system with a slow leak and spotting the leak with a residue...

My ‘92 Camry had a slow leak, needing to be topped off every couple years. When the compressor seized up, I replaced it, the drier, and the condenser (the heat exchanger in front of the radiator). When I got the condenser out, there was a thick 3” diameter oily dirty spot on the front side. It had been leaking for a long time from a rock hitting it. Apparently enough oil leaked out the lubricant got low and resulted in the compressor seizing up.

So in my experience, a slow leak will definitely result in lubricant leaking out. From what I’ve read, the lubricant gets aerosolized by the compressor when it’s running, and distributes the lubricant throughout the system, hence the lube leaks along with the Freon. In an idle AC system, a leak will not cause loss of lubricant because it’s not aerosolized.

@john-smith , before you refill with refrigerant, you should replace the receiver/drier since it is at zero pressure. Moisture can make its way into a fully discharged system, and will cause problems if not removed by a functioning drier. They can absorb only a limited amount of moisture. Then the system should be vacuumed down to zero pressure to remove all the air before charging it. Let it sit at full vacuum for at least an hour to verify there are no bad leaks. Then charge it with Freon. I bought a vacuum pump at Harbor Freight that works good. This one. If you do replace the drier, according to this thread you should add 1.3 ounces of PAG46 oil.

Here‘s a helpful troubleshooting page from Denso. Not much is applicable to your situation, but it might be helpful someday.

 

uhh... you take issue with my statement: "you would not necessarily have an oily residue "

but you say: "So in my experience, a slow leak will definitely result in lubricant leaking out. "

when the accurate statement is my 92' leaked for years and it had an oily spot...

yeah, my statement is much more accurate, and yours is based on years of leaking and refilling...

so, if you have a leak: "you would not necessarily have an oily residue "

and another above post: "In an idle AC system, a leak will not cause loss of lubricant because it’s not aerosolized. "

uhh... in an idle AC system, the pressure equalizes everwhere, it does not stay a aerosol in one place and a liquid in another, it's the same everywhere... it equalizes

 

uhh... you take issue with my statement: "you would not necessarily have an oily residue "

No, I‘m taking issue with this statement where you contradicted yourself immediately after the above statement.

…in fact you never hear of this, i.e. a system with a slow leak and spotting the leak with a residue..

uhh... in an idle AC system, the pressure equalizes everwhere, it does not stay a aerosol in one place and a liquid in another, it's the same everywhere... it equalizes

Yes, of course the pressure equalizes everywhere in an idle system. I never said otherwise. My point was that in an idle system, the lubricant would not remain aerosolized. It would gather in the low points of the compressor, condenser, evaporator, and drier. A trivial amount would collect in the hoses and metal lines where it could leak out at the joints. Therefore it won’t leak out a significant amount in an idle system with leaks. Just the gaseous freon would.

 

Low pressure is at proper pressure but high pressure side is same pressure as low with engine running. It blows fairly cold air at idle. If you drive it vent temps start to increase.

This sounds to me like a bad compressor.

edit: I forgot to mention pressures should be checked with the engine running at a high idle. This will decrease the low side and increase the high side pressure.

edit #2: I reread your post and see in your last paragraph that you revved it up to 2500 with no change in pressures.

Seems like either the condenser is clogged or compressor is bad just not sure how to tell which one.. I suspect the compressor.

A clogged condenser would cause the high side pressure to be really high. Any restriction (other than the expansion valve) on the high side would do that.

I see there is an expansion valve listed but never heard of those so no idea what it does.

The expansion valve is a controlled restriction that causes the incoming high pressure liquid freon to turn into a lower pressure gas. This makes the gaseous freon really cold, so when it passes through the evaporator in the dash, it cools the air passing through it. Toyota’s expansion valves have a diaphragm element on top that adjusts the liquid freon flow to keep the temperature slightly above freezing. If it gets below freezing, the water that condenses on the evaporator would freeze and clog the airflow passing through it. In the pic below, the disk shaped piece on top is the diaphragm which pushes/pulls on the rod to adjust the flow of Freon. An expansion valve can cause poor cooling by not allowing enough freon to pass, but that would also cause the high side pressure to be very high, which isn’t the case with yours.

Lastly, here’s a brief YouTube video explaining it in more detail without getting too technical.

 

This sounds to me like a bad compressor.

edit: I forgot to mention pressures should be checked with the engine running at a high idle. This will decrease the low side and increase the high side pressure.

edit #2: I reread your post and see in your last paragraph that you revved it up to 2500 with no change in pressures.
A clogged condenser would cause the high side pressure to be really high. Any restriction (other than the expansion valve) on the high side would do that.
The expansion valve is a controlled restriction that causes the incoming high pressure liquid freon to turn into a lower pressure gas. This makes the gaseous freon really cold, so when it passes through the evaporator in the dash, it cools the air passing through it. Toyota’s expansion valves have a diaphragm element on top that adjusts the liquid freon flow to keep the temperature slightly above freezing. If it gets below freezing, the water that condenses on the evaporator would freeze and clog the airflow passing through it. In the pic below, the disk shaped piece on top is the diaphragm which pushes/pulls on the rod to adjust the flow of Freon. An expansion valve can cause poor cooling by not allowing enough freon to pass, but that would also cause the high side pressure to be very high, which isn’t the case with yours.
View attachment 219194
Lastly, here’s a brief YouTube video explaining it in more detail without getting too technical.

Thanks for the explanation of the expansion valve. It must be under the dash with the evaporator because I didn't see under the hood.

For the price i think I am going to replace the compressor and condenser given the price of replacement filter/cartridge and call it a day. I have a service manual coming to review before I go any further.

I have a backflush setup and was going to backflush the evaporator and lines when I replace the compressor but they say not to backflush expansion valves. Service manual should give me more insight where it is. Never heard any bad noises so may not be metal shards in the system, so many compressor styles in use, some with solenoids. I'll check the compressor and lines closely when I pull them.

Thanks to everyone who responded, you've all been a big help !

 

One last point… In a system that’s running properly, it should deliver a 40°F temperature change. So if it’s 100°F outside, it should be putting out 60°F air at the vents with it running at max cooling, highest fan speed, engine RPM above 1500. I use a digital cooking thermometer like this:

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