Should I FLUSH OUT my A/C system w/ new compressor install?

[SyberTiger]

Let me preface this by saying that my A/C compressor has not locked-up, blown-up or failed. I have a pin-hole leaking hose assembly where you can see PAG oil around the rubber hose to metal crimped fittings. I've recharged it a few times over the last year only for the refrigerant to slowly leak out. When I've recharged it would appear that the high pressure side is sitting a bit lower than it should so I've decided to replace the compressor while I change out the leaking hose....it is after all the original 2002 compressor which runs almost everyday here in Florida.

Just for chits-n-giggles, I'll be replacing the receiver/dryer, compressor, high pressure hose assembly and the orifice tube. I'm not expecting to see any weirdness or junk in the orifice tube. Therefore, I do not plan on replacing the condenser and I'll be reusing the evaporator and the other hoses. I doubt the condenser can be flushed because of the very tiny passages but the evaporator should be flush-able as well as old hoses.

Should I bother flushing the evaporator if there isn't any evidence of contamination or metal crude? And, if there's no need I'm wondering how much PAG oil remains in the old components to be reused? I plan to follow the specs on PAG and refrigerant quantity but if there's PAG still in the system because I didn't flush how do I adjust the amount to add?

 

[imp]

Let me preface this by saying that my A/C compressor has not locked-up, blown-up or failed. I have a pin-hole leaking hose assembly where you can see PAG oil around the rubber hose to metal crimped fittings. I've recharged it a few times over the last year only for the refrigerant to slowly leak out. When I've recharged it would appear that the high pressure side is sitting a bit lower than it should so I've decided to replace the compressor while I change out the leaking hose....it is after all the original 2002 compressor which runs almost everyday here in Florida.

Just for chits-n-giggles, I'll be replacing the receiver/dryer, compressor, high pressure hose assembly and the orifice tube. I'm not expecting to see any weirdness or junk in the orifice tube. Therefore, I do not plan on replacing the condenser and I'll be reusing the evaporator and the other hoses. I doubt the condenser can be flushed because of the very tiny passages but the evaporator should be flush-able as well as old hoses.

Should I bother flushing the evaporator if there isn't any evidence of contamination or metal crude? And, if there's no need I'm wondering how much PAG oil remains in the old components to be reused? I plan to follow the specs on PAG and refrigerant quantity but if there's PAG still in the system because I didn't flush how do I adjust the amount to add?

Generally, the replacement compressor will have been pre-charged with oil. Check on that, ask the supplier, if the accompanying data don't say. If not pre-charged, I usually add new oil in the quantity specified for the system, ignoring what little may be left in lines, receiver, coils. Unless the compressor fails by belching it's guts into the circuit, flushing is a moot thing. imp

 

[MAS Tequila]

Unless the current charge comes out black there is no reason to flush the system.

When you evacuate or vacuum the system it will draw out any remnants of the previous charge.

Pour the oil out of the new compressor before installing so you can measure what is going in and have the correct amount, guessing is a very bad thing.

If you don't have an AC manifold set-up with gauges and a vacuum, find access to them or pay someone to do that part.

Otherwise you're wasting your time and money.

This past summer I installed a new complete system minus the evaporator in my 2000 Mountaineer using the Harbor Freight Vacuum and manifold gauges.

It went easier than expected.

Be sure to get the installation kit with the O-rings, you'll be sorry if you don't.

The inexpensive plastic disconnect tools work better with the Ford ac quick connects than the more expensive ones.

I bought the more expensive ones first and they wouldn't work with all of the connections.

Fuel Line and A/C Quick Disconnect Tool 6 Pc

Good Luck

 

[SyberTiger]

Generally, the replacement compressor will have been pre-charged with oil. Check on that, ask the supplier, if the accompanying data don't say. If not pre-charged, I usually add new oil in the quantity specified for the system, ignoring what little may be left in lines, receiver, coils. Unless the compressor fails by belching it's guts into the circuit, flushing is a moot thing. imp

Like you said, the new compressor has some oil in it but without flushing the evaporator and it being unlikely that the condenser can be flush along with reusing some hoses I was trying to figure out how much PAG residue would still be in the system. Would anyone dare to estimate the remaining components would still have 1 or 2 ounces of PAG still in there?

 

[SyberTiger]

Unless the current charge comes out black there is no reason to flush the system.

When you evacuate or vacuum the system it will draw out any remnants of the previous charge.

Pour the oil out of the new compressor before installing so you can measure what is going in and have the correct amount, guessing is a very bad thing.

If you don't have an AC manifold set-up with gauges and a vacuum, find access to them or pay someone to do that part.

Otherwise you're wasting your time and money.

This past summer I installed a new complete system minus the evaporator in my 2000 Mountaineer using the Harbor Freight Vacuum and manifold gauges.

It went easier than expected.

Be sure to get the installation kit with the O-rings, you'll be sorry if you don't.

The inexpensive plastic disconnect tools work better with the Ford ac quick connects than the more expensive ones.

I bought the more expensive ones first and they wouldn't work with all of the connections.

Fuel Line and A/C Quick Disconnect Tool 6 Pc

Good Luck

I have my own manifold gauges but "free rented" the vacuum pump from Autozone, something I've done on past A/C projects. I've got the fancier disconnect tools from HF but maybe I'll pick up the plastic ones too per your recommendation. I have the complete O-ring kit.

I'm curious to know why you replaced your compressor as it sounds like it never locked up and therefore didn't have "black death" in the system. Was the high or low pressure side too low? Did you replace any other components other than the compressor itself?

 

[MAS Tequila]

My clutch was bad and the compressor was likely original.

The only thing I didn’t replace was the evaporator.

My system was leaking down fairly quickly, so I replaced the majority of it.

I probably would have replaced the evaporator if it didn’t require all of the disassembly.

My Mountaineer is lifted, so that makes some things more difficult.

My AC is almost on par with the newer systems now.

 

[SyberTiger]

Here's some info from an online article I came across with regard to how much oil remains in the system per component. In other words, if you do not flush out the evaporator, for example, this implies that 2 oz are still in it.

"A system flush is also a good practice if, for some reason, the amount of lubricant in the A/C system is in doubt.
If simply replacing an A/C component, use this as a guideline for oil replacement:

Component Amount Of Lubricant To Add:
Accumulator 2 oz.
Condenser 1 oz.
Evaporator 2 oz.
Filter Drier 1 oz.

In the event that the entire system has been flushed, unless otherwise specified by the OE, best practice is to add half the total oil capacity in the compressor and the other half in the accumulator or receiver dryer. Doing this ensures that the compressor will not start up dry and that lubrication will be distributed evenly throughout the system.

To prevent oil slugging and potential internal damage to the compressor, after the hoses are reattached, manually rotate the compressor shaft 10 times."