I posted a similar question on one of the AC forums but nobody has answered it.

Ac died about a year and a half ago, compressor just clicking. The van has front and rear AC and calls for 43oz of refrigerant.

I just replaced the compressor and the drier as I didn't/don't have enough money to replace everything. I added 8 oz of oil as the old compressor only had a drop in it and the old drier had none. I figured the compressor should have around 7 oz and the drier should have around 1 oz. I arrived at this based on how much oil the system should have in it and how much each component should hold. And I don't believe the system had no oil as it still had a charge before I opened it up.

So I replaced the compressor and drier and pulled a vacuum on it for about an hour, and then let it sit to check for leaks. Everything checked out so I charged into the vacuum. Unfortunately the gauge set I used didn't allow me to charge into it so I charged it blind, with the gauges.

So here I am with the AC working, but not cooling as well as it should. My pressures are off. 50psi low and 380psi high. The high may drift into the 420 range for a few seconds but tends to sit around 380. I was looking for a low of 50-55psi and a high of 300-325psi. The compressor cycles but only sometimes. During my last test it didn't cycle at all, just stayed on. And with the vehicle off I have 135psi low and 110psi high.

When I connected to the high port on the drier I had a surprising amount of oil spray out. Wasn't expecting that.

So what am I likely looking at. Did I clog something by putting 8oz of oil in the new compressor? If this is a possible cause can I vent some of the oil from the drier? It's also entirely possible that I put too much 134a in it as well. Hopefully some of you experts may be able to point me in the right direction on this. I stressed over the oil amount because it was only a semi-educated guess!

I'm close, and the van keeps us from sweating right now in 100+ weather, but I want to make it as right as I can without spending money that I don't have.

Thank you in advance for any and all help that you may be able to provide.

 

Try doing this expansion valve test.
A/C EXPANSION VALVE
WARNING: Refer to the applicable warnings and cautions for this system before performing the following operation. Failure to follow the warnings and cautions could result in possible personal injury or death.

NOTE: The A/C expansion valve should only be tested following testing of the A/C compressor.

NOTE: Liquid CO² is required to test the A/C expansion valve. This material is available from most welding supply facilities. Liquid CO² is also available from companies which service and sell fire extinguishers.

When testing the A/C expansion valve, the work area and the vehicle temperature must be 21° to 27° C (70° to 85° F). To test the expansion valve:

Connect a charging station or manifold gauge set to the refrigerant system service ports. Verify the refrigerant charge level.
Close all doors, windows and vents to the passenger compartment.
Set the A/C-heater controls so that the A/C compressor is operating, the temperature control is in the highest temperature position, the mode-air doors is directing air output to the floor and the blower motor operating is operating at the highest speed.
Start the engine and allow it to idle. After the engine has reached normal operating temperature, allow the passenger compartment to heat up. This will create the need for maximum refrigerant flow into the A/C evaporator.
If the refrigerant charge is sufficient, the discharge (high pressure) gauge should read 965 kPa to 1655 kPa (140 psi to 240 psi). The suction (low pressure) gauge should read 138 kPa to 207 kPa (20 psi to 30 psi). If OK, go to Step 6. If not OK, replace the faulty A/C expansion valve.
WARNING:

Protect the skin and eyes from exposure to liquid CO² or personal injury can result.


If the suction (low pressure) gauge reads within the specified range, freeze the A/C expansion valve for 30 seconds using liquid CO² or another suitable super-cold material. Do not spray R-134a or R-12 refrigerant on the A/C expansion valve for this test. The suction (low pressure) gauge reading should drop by 69 kPa (10 psi). If OK, go to Step 7 If not OK, replace the faulty A/C expansion valve.
Allow the expansion valve control head to thaw. The suction (low pressure) gauge reading should stabilize at 138 kPa to 207 kPa (20 psi to 30 psi). If not OK, replace the faulty A/C expansion valve.
When expansion valve testing is complete, test the overall A/C system performance.

 

Thanks for the reply. I can test the expansion valves.

I was hoping to address my oil concerns. Got maybe a drop out of the old compressor and nothing out of the old drier. Was adding 8oz of oil to the compressor justified? I added the oil before I installed it. I had what seemed to be a lot of oil come out of the drier when I connected the gauge to the high port on it.

Also, am I looking for the correct readings? At 100f ambient temperature I'm looking for 50-55 low and 315-325 high? About right?

 

Here is the chart from the 2004 service manual Dave. You probably have added way too much oil to the system and it can be a pain to remove. Had an '07 a couple of weeks ago where just the rear wouldn't cool, not at all, but the front worked fine. Replaced the rear expansion valve and no cooling. Ended up replacing everything from the front lines all the way back to the rear evaporator and it ended up just having too much oil in the system. Just kept blowing the lines out til it worked.


STANDARD PROCEDURE - REFRIGERANT OIL LEVEL

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - FRONT - WARNING - A/C PLUMBING and (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - FRONT - CAUTION - A/C PLUMBING).
CAUTION: Use only PAG oils that are designed to work with R-134a refrigerant and the A/C compressor in the vehicle. Refer to the underhood A/C System Specification Label.
It is important to have the correct amount of lubricant in the A/C refrigerant system to ensure proper lubrication of the A/C compressor. Too little lubricant will result in damage to the compressor. Too much lubricant will reduce the cooling capacity of the A/C system and consequently result in higher discharge air temperatures.
The lubricant used in the compressor is polyalkalene glycol PAG lubricant. Only the refrigerant lubricant approved for use with this vehicle should be used to service the system. Do not use any other lubricant. The lubricant container should be kept tightly capped until it is ready for use. Refrigerant lubricant will quickly absorb any moisture it comes in contact with.
It will not be necessary to check the oil level in the A/C compressor or to add oil, unless there has been an oil loss. An oil loss may occur due to a rupture or leak from a refrigerant line, connector fitting, component or component seal. If a leak occurs, add 30 milliliters (1 fluid ounce) of the recommended refrigerant oil to the refrigerant system after the repair has been made. Refrigerant oil loss will be evident at the leak point by the presence of a wet, shiny surface around the leak.
REFRIGERANT OIL LEVEL CHECK

When an air conditioning system is first assembled at the factory, all components (except the A/C compressor) are refrigerant oil free. After the refrigerant system has been charged with (R-134a) refrigerant and operated, the oil in the A/C compressor is dispersed through the lines and components. The A/C evaporator, A/C condenser, and receiver/drier will retain a significant amount of oil. Refer to the A/C Component Refrigerant Oil Capacities table. When a component is replaced, the specified amount of refrigerant oil must be added. When the compressor is replaced, the amount of oil that is retained in the rest of the system must be drained from the replacement A/C compressor. The oil capacity of the system, minus the amount of oil still in the remaining components (refer to the oil capacity chart below) can be measured and poured into the suction port of the A/C compressor. When a line or component has ruptured and oil has escaped, the receiver/drier must be replaced along with the ruptured component.
Example: On an A/C system the A/C evaporator retains 60 ml. (2 oz.). The A/C condenser retains 30 ml. (1 oz.) of oil, and system capacity may be 150 ml. (5.00 oz.) of oil.
150 ml. minus 90 ml. equals 60 ml. (2.00 oz.).
A/C COMPONENT REFRIGERANT OIL CAPACITIES

Front A/C / Front & Rear A/C - COMPONENT / ml / fl oz / ml / fl oz. Total System Fill- 180/ 6.1/ 300/ 10.14. Receiver/Drier- 25/ 0.9/ 25/ 0.9. A/C Condenser- 50/ 1.8 /50/ 1.8. Front Evaporator- 50/ 1.8/ 50/ 1.8. Rear Evap. (including underbody lines)- N/A / N/A / 50/ 1.8. A/C Compressor Drain and measure the oil from the old compressor - See text above.

VERIFY REFRIGERANT LUBRICANT LEVEL

1. Recover the refrigerant from the system.
2. Disconnect the refrigerant lines from the A/C compressor. Cap open lines to prevent moisture from entering the system.
3. Remove A/C compressor from the vehicle.
4. From the suction and discharge ports on the A/C compressor, drain the lubricant from the compressor.
5. Add the system capacity minus the capacity of the components that have not been replaced. Refer to the A/C Component Refrigerant Oil Capacities chart. Add lubricant through the suction and discharge ports on the A/C compressor.
6. Install the A/C compressor and connect the refrigerant lines. Then evacuate and charge refrigerant system.
7. Most reclaim/recycling equipment will measure the lubricant being removed. This amount of lubricant should be added back to the system. If a new A/C compressor is being installed, drain the lubricant from the used compressor, measure the amount drained and discard the used lubricant. Drain the lubricant from the new A/C compressor into a clean container. Return the amount of lubricant measured from the used compressor, plus the amount reclaimed from the system back into the new A/C compressor. Refer to the reclaim/recycling equipment manufacturers instructions.

 

So it's time to show my ignorance.

I am now replacing the compressor, drier, condenser and both expansion valves. I'm also going to flush the system. Doing the whole thing. But there's quite a bit I don't know about the procedure.

1: Where are the front and rear expansions valves located?
2: How should I distribute the oil in the system? I' don't think dumping 14oz of oil in the compressor would be the right thing to do?
3: How do I flush the front and rear? I'm guessing that they would be two separate services.

I know the compressor, drier, and condenser won't be too bad, just don't know about the rest, and need to massively increase my knowledge level before Saturday morning.

Thanks

 

Front expansion valve is just behind the drier. Not too tough. The rear expansion valve is tougher, you have to pull the rear hvac housing which is behind the right quarter trim.

Flushing the system is done with a flush solution and a canister you can charge with air. Probably don't have one of those so just try blowing compressed air through the lines. each component should be flushed seperately.

 

I've done this before in my old Taurus SHO. But in that case I replaced everything and only had to flush the evaporator. I filled it flush and the blew it through with my compressor. But in this case there is more hardware to deal with. I'm not sure where the line goes from the front to rear.

I'm a little dense. Does your earlier post describe how I should distribute the oil in the system? I know it explains how much different components hold but don't know if that is how I should distribute it. And I thought the total oil capacity is 14oz.

 

Bump1

 

If you buy a new compressor, it comes with a full system charge of oil. The oil distributes itself. It hitches a ride on the freon and just runs in circles. When you shut the system off, the oil just sits where it is until you start the a/c again and then it runs in circles again. After you charge the system, you turn the compressor over a few times by hand to get the oil out of the compressor cylinders and then fire it up. The oil will take care of itself after that.

 

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