AC Refrigerant Oil

[Joe D]

My A/C system stopped working recently, I took the car to the repair shop and they informed me the system was dry and the most likely problem was the condenser based on its physical condition. In order to save some money I am going to replace the condenser / dryer and valve cores myself. I was also looking into the possibility of buying or renting the vacuum pump and gauges so i can do the recharge myself.
My question is do I need to add refrigerant oil to the system due to the leak and drawing a vacuum on the system?
What is the best way to install the oil in the system?
What other system components should I consider replacing while the system is open?
The vehicle is a 2003 Honda Accord, LX 4-cyl, manual transmission.

Topic

[Richard Kirshy]

See if these are helpful:

[Mike]

You need to replace the oil that the condenser and the receiver drier normally retain.
If you use the PAG 46 oil that contains fluorescent dye, it will make detecting any future leaks much easier.
Unless your replacement condenser is a junkyard part (not a good idea), the condenser should have a new receiver/drier attached.
The one recommended replacement part for when the system is opened that you didn’t mention is the expansion valve.
Unless there’s a huge amount of oil sprayed all over the place where the leak is, I don’t think you would need to replace more than 1 to 1.3 ounces of oil.
Too much is bad, as is too little.
The underhood sticker for the AC should tell you the exact amount of R134a to charge the system.
Bookmark this post for future reference:
https://www.ericthecarguy.com/kunena/8-Service-and-Repair-Questions-Answered-Here/65468-correct-a-c-pag-oil-amount#174662

[Joe D]

Thanks for your advice. I am still a little concerned with the amount of oil to replace. Does drawing a vacuum on the system draw the oil out?

[Joe D]

The other thing I forgot was how to put the oil in?

[Mike]

Adding the oil is simple; using a funnel, pour it into the condenser when you install it–before drawing a vacuum.
Be sure to apply some PAG oil to the new o rings when you reconnect the hoses.

Drawing down a vacuum does not remove any oil.
What it actually does is boil away all the remaining moisture that’s in the ac system.

I would draw down a vacuum for an hour, then let it sit for a half hour to make sure the vacuum holds.
If it doesn’t, you have a leak somewhere.

[Joe D]

Well I wanted to verify no system pressure prior to working on my AC system, so I momentarily depressed the valve cores on both the hi and low side refrigerant lines. To my surprise the system still contained pressure. The shop that I had check it out said the system was empty. I am assuming that the pressure is lower than the pressures capable of being read on the manifold gauges they were using when they did the check. So my question is if there is in fact a significant ac system leak wouldn’t all of the refrigerant pressure have dissipated by now. I am considering recharging the system possibly with refrigerant dye prior to replacing the condenser. Keep in mind the shop I took this to did not use dye to determine that the condenser was leaking, they were only assuming this based on external condition of the condenser. Any advice on how I should proceed will be greatly appreciated.

[Wyr Twister]

Honestly , you need a set of gauges / hoses to do much of anything concerning A/C or HVAC .

Does your compressor have a electromagnetic clutch ? All the automotive compressors I have worked on do .

Is the clutch pulling in when you turn on the A/C ? ( May not is a low pressure sensor / switch is inhibiting the clutch circuit . ) Check to see if you are getting 12 VDC to the clutch coil .

If the clutch is pulling in , hook up the gauges / hoses ( purge the air from them ) .

What are your pressures ? Even if the clutch is not pulling in , what are the pressures ? Report back with data .

Look for traces of oil leaks around the compressor shaft . And at every point where there is a mechanical connection from one component to another . Often if you have a refrigerant leak , a trace of oil will leak out also .

Has the A/C ever been serviced / worked on before ? If not , it would not be surprising for a 2003 model to loose enough refrigerant diminish cooling capacity .

I would try these things before even thinking about replacing components . Otherwise you end up throwing paers at it .

[Joe D]

The compressor does not turn on due to low pressure. I disconnected the pressure switch connector and check the pressure switch contacts were open. I then jumpered the connector terminals and verified the compressor running. I inspected all tubing and components as best I could. The only oil residue I saw was from the high side port on the tubing. As I stated the shop I took it to told me the system was empty. I wanted to verify this by momentarily depressing the low and hi side valve core stems and found some pressure still present. I would assume if I had a significant leak there would be no pressure in the system. To the best of my knowledge the system has never been serviced. I am the original owner. I do plan on getting manifold gauges prior to proceeding with a recharge. Thanks for your response.

[Wyr Twister]

If you still have pressure in the system , that is good news . It means you do not have to worry about air ( that contains moisture ) having entered the system . Moisture inside the system is the enemy of A/C , refrigeration systems .

I try to replace the Schrader Valves at the service ports , as preventive maintenance . By those made for A/C , not for tire valve stems . May be no difference , but I do not take the chance .

I agree , if you add refrigerant , use the products that have florescent dye . DO NOT use one of the stop leak products . Have heard many horror stories about the stuff . Again , I do not take the chance .

You need , at the very minimum , a hose setup with a gauge . Add refrigerant only through the low / suction service port .

A/C is very much about temperatures & pressures . With out a way of reading pressures , you are flying blind .

Now , I have said my peace . If you proceed , slowly add refrigerant as a gas , into the low side service port . Monitor the temperature of the returning refrigerant gas going to the suction side of the compressor . And the discharge air temp at the inside cabin vent .

Too cold is not better . The vent temp & suction temp need to be enough above freezing to avoid freezing up / frosting up the evaporator coil . Freeze up the coil and things go from bad to worse , as the frost / ice blocks off air flow & the coil will get colder . More ice / frost .

You may need to put a box fan in front of , blowing additional air into the radiator / condenser coil . You may need to run the engine faster than idle .

With my limited talents , I do a better job of charging an A/C if the Out Side Air temp is in the 80’s or above . Preferably the 90’s .

If you get to the point where your suction pressure is good ( best I remember , between 30 – 35 PSI with R-134a ) and you are getting about 40 – 50 degree air from the vents , stop there . Too much refrigerant messes up the temperatures & pressures , and does not cool as well as the correct charge . May also cause other problems .

But , remember , the most accurate way to charge the system is by starting with an empty system and weighing in the proper amount of refrigerant .

If that works , then keep track to see if the refrigerant is slowly leaking out . If it does over the next days , weeks , months , go to the parts store & buy the yellow glasses & UV flashlight . Start looking for leaks . Better after dark . If you have color around the service fittings that may have been from disconnecting the hose / hoses , wash it off with rubbing alcohol .

The florescent dye method is the best I have personally used .

As long as you maintain pressure in the system , no need to worry about vacuuming the system down .

Also , if the compressor is pumping after you get sufficient pressure into the system to satisfy the low pressure switch , you probably / maybe do not need a new compressor . Unless it is making bad noises or oil / refrigerant coming out of the system has black contamination ( black death ) .

Good luck
God bless
Wyr

[James P Grosso]

The vacuum does not pull out the oil. It actually boils off any water in the system.

[Wyr Twister]

That was pretty much the case with mineral oil & R-22 or R-12 .

I read that the synthetic oil used with R-134a or R-410a are more hygroscopic ( absorbs and retains moisture ) than mineral oil . There fore , it is said it is much more difficult to draw off the moisture with vacuum .

If the system uses synthetic oil , I try to use the pump for a lot longer than with mineral oil .

When it is all said and done , it is the job of the accumulator / dryer to remove the remaining moisture .

God bless
Wyr

[Andrew Phillips]

There is a faulty assumption going on here. The OP depressed the schraders and found pressure. That does not necessarily mean that there is refrigerant in the system. Since a shop has previously worked on the system, it is quite possible that the system was empty, and that the technician pressurized it slightly with nitrogen to check for leaks, which is a very common practice. A small leak will have a allowed the refrigerant to leak out over time, but there has not been enough time for the nitrogen to leak out yet. The compressor will stop turning on below a certain PSI. This means there will still be pressure in the system, but not enough to energize the compressor. Without gauges, there is no way to know how much (or how little) pressure there is in the system. There is also no way for the OP to verify what gasses are actually in the system. I would strongly recommend having a shop repair this system.

[Author]

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