A/C System Question

[joker]

It appears that my A/C system has quit working. The compressor clutch doesn't engage at all, even with the low pressure switch jumped. A new compressor clutch is around $100 and a new compressor around $250. Would it be worth it to try and just replace the clutch or better just to replace the compressor?

[Craig K.]

How old is the original compressor and how many miles are on it?
Also is it R12 originally (I think ore-1994), or R134?

If it is R12 and/or more than 100-125k miles I would just replace it all.
If you have a leak somewhere and all the Pag oil has been drained of the system, then the compressor may be shot anyway.

[joker]

How old is the original compressor and how many miles are on it?
Also is it R12 originally (I think ore-1994), or R134?

If it is R12 and/or more than 100-125k miles I would just replace it all.
If you have a leak somewhere and all the Pag oil has been drained of the system, then the compressor may be shot anyway.

It is a 2000 with 79k miles. I am not sure if it has a leak or not. Jumpering the low pressure switch should have caused the clutch to engage but didn't, so I am sure the clutch is bad. There is also a wired knocking sound coming from the compressor clutch area. The pulley still spins, but the clutch never engages. It is possible that it has leaked down, but without taking it to a shop or getting a gauge set I have no way to tell.

I am fairly certain that the factory system uses r12. If I replace the compressor I would like to just go ahead and do a conversion to r134, which I believe also includes replacing all of the o-rings.

From what I can tell the cost of buying parts and needed tools should still be less than getting it replaced at a local shop.

[QWKSNKE]

R134 started in 94. So you have a 134 system.

Honestly its a tossup on which to buy. I normally to the clutch only on a car but I normally know for sure thats all I need. Since you mentioned something about a noise occurring now, I would probably replace it all ass well. Sounds like you could have a bad compressor bearing

[joker]

R134 started in 94. So you have a 134 system.

Honestly its a tossup on which to buy. I normally to the clutch only on a car but I normally know for sure thats all I need. Since you mentioned something about a noise occurring now, I would probably replace it all ass well. Sounds like you could have a bad compressor bearing

Thanks for the info.

I think that I am going to pick up a gauge set and Vacuum pump. That will let me check the pressure to see if the system has leaked down, if it hasn't I will get a shop to do the recovery. Then from my understanding, it should just involve replacing the compressor and dryer, pulling a vacuum, and refiling.

I thought about trying to do a system leak check while I am at it, but am not sure the best way or if it is really needed. I read somewhere that the test dye is bad for systems, but am not sure if that is true.

[joker]

Something I am not quite clear on. Do I need to add oild directly to the new compressor, and then add oil with the charge, or can I just install the new compressor and charge with the mixed r134/oil.

[Craig K.]

I believe oil should come in the new compressor already, but if not I think you need to add it prior to charging the system.

I never really got into working on A/C systems, it’s the one thing I would pay someone for (as long as they offered a warranty).

[joker]

I believe oil should come in the new compressor already, but if not I think you need to add it prior to charging the system.

I never really got into working on A/C systems, it’s the one thing I would pay someone for (as long as they offered a warranty).

From my understanding the compressors ship without any oil. According to the ford service manual and the Haynes manual you have to measure the amount drained from the old compressor in order to determine how much to add to the new compressor. For the dryer/accumulator you have to drill two holes in the bottom and measure the drained fluid to determine the amount for the new unit. If replacing the condenser or evaporator then you must add oil to those as well.

I can see why you would pay someone rather than messing with it yourself. It is a somewhat complicated system to work on from what I am learning. There seems to be quite a bit of difference in opinion on the subject when trying to gather info from forums, websites, and youtube videos. Personally, it is just much more cost effective and self sufficient to just learn it myself. When it is all said and done, I should have around $400 - $500 in it replacing the condenser, compressor, and accumulator as well as a complete system flush and recharge. I also hate having to search for a good, honest, dependable mechanic. Those aren't always easy to find, particularly in rural areas.

Edit: I was wrong about the oil. The compressor that I purchased comes with 3 - 4 oz of oil from the factory, you have to add more only if needed according to the manufacturer recommendations.

In case anyone else ever stumbles upon this, here is what Ford recomends in the service manual:

1. NOTE: Service A/C compressors are shipped without compressor oil. (I am guessing that this applies to Motocraft compressors that are sent to service departments. My after market did ship with oil)
Rotate the A/C compressor shaft six to eight revolutions while collecting oil in a clean measuring
device.
�� If the amount of oil drained from the old A/C compressor is between 85-142 ml (3-5
ounces), pour the same amount plus 30 ml (1 ounce) of clean PAG Refrigerant
Compressor Oil (R-134a Systems) F7AZ-19589-DA (Motorcraft YN-12-C) WSH M1C231-
B or equivalent into the new A/C compressor.
�� If the amount of oil that was removed from the old A/C compressor is greater than 142 ml
(5 ounces), pour the same amount drained of clean PAG Refrigerant Compressor Oil (R-
134a Systems) or equivalent into the new A/C compressor.
�� If the amount of oil that was removed from the old A/C compressor is less than 85 ml (3
ounces), pour 85 ml (3 ounces) of clean PAG Refrigerant Compressor Oil (R-134a
Systems) or equivalent into the new A/C compressor.
2. For the suction accumulator/drier, drill one 13 mm (0.52 in) hole in the suction accumulator/drier
cylinder and drain the oil into a calibrated container.
�� Add a quantity of new oil to match that drained from the old suction accumulator/drier
plus 60 ml (2 ounces) of clean PAG Refrigerant Compressor Oil (R-134a Systems) or
equivalent.
3. For the A/C evaporator core, add 89 ml (3 ounces) of clean PAG Refrigerant Compressor Oil
(R-134a Systems) or equivalent to the suction accumulator/drier inlet tube.
4. For the A/C condenser core, add 30 ml (1 ounce) of clean PAG Refrigerant Compressor Oil (R-
134a Systems) or equivalent to the A/C condenser core or the suction accumulator/drier inlet
tube.
5. Add 60 ml (2 ounces) of clean PAG Refrigerant Compressor Oil (R-134a Systems) or equivalent
to the suction accumulator/drier inlet tube when carrying out each of the following repairs:
�� installation of a new A/C evaporator core orifice
�� installation of a new A/C compressor pressure relief valve (19D644)
�� installation of a new refrigerant line
�� repair of an O-ring seal leak
�� repair of a charge port leak

[QWKSNKE]

Good info to know as I never knew that about OEM compressors

From my understanding the compressors ship without any oil. According to the ford service manual and the Haynes manual you have to measure the amount drained from the old compressor in order to determine how much to add to the new compressor. For the dryer/accumulator you have to drill two holes in the bottom and measure the drained fluid to determine the amount for the new unit. If replacing the condenser or evaporator then you must add oil to those as well.

I can see why you would pay someone rather than messing with it yourself. It is a somewhat complicated system to work on from what I am learning. There seems to be quite a bit of difference in opinion on the subject when trying to gather info from forums, websites, and youtube videos. Personally, it is just much more cost effective and self sufficient to just learn it myself. When it is all said and done, I should have around $400 - $500 in it replacing the condenser, compressor, and accumulator as well as a complete system flush and recharge. I also hate having to search for a good, honest, dependable mechanic. Those aren't always easy to find, particularly in rural areas.

Edit: I was wrong about the oil. The compressor that I purchased comes with 3 - 4 oz of oil from the factory, you have to add more only if needed according to the manufacturer recommendations.

In case anyone else ever stumbles upon this, here is what Ford recomends in the service manual:

1. NOTE: Service A/C compressors are shipped without compressor oil. (I am guessing that this applies to Motocraft compressors that are sent to service departments. My after market did ship with oil)
Rotate the A/C compressor shaft six to eight revolutions while collecting oil in a clean measuring
device.
�� If the amount of oil drained from the old A/C compressor is between 85-142 ml (3-5
ounces), pour the same amount plus 30 ml (1 ounce) of clean PAG Refrigerant
Compressor Oil (R-134a Systems) F7AZ-19589-DA (Motorcraft YN-12-C) WSH M1C231-
B or equivalent into the new A/C compressor.
�� If the amount of oil that was removed from the old A/C compressor is greater than 142 ml
(5 ounces), pour the same amount drained of clean PAG Refrigerant Compressor Oil (R-
134a Systems) or equivalent into the new A/C compressor.
�� If the amount of oil that was removed from the old A/C compressor is less than 85 ml (3
ounces), pour 85 ml (3 ounces) of clean PAG Refrigerant Compressor Oil (R-134a
Systems) or equivalent into the new A/C compressor.
2. For the suction accumulator/drier, drill one 13 mm (0.52 in) hole in the suction accumulator/drier
cylinder and drain the oil into a calibrated container.
�� Add a quantity of new oil to match that drained from the old suction accumulator/drier
plus 60 ml (2 ounces) of clean PAG Refrigerant Compressor Oil (R-134a Systems) or
equivalent.
3. For the A/C evaporator core, add 89 ml (3 ounces) of clean PAG Refrigerant Compressor Oil
(R-134a Systems) or equivalent to the suction accumulator/drier inlet tube.
4. For the A/C condenser core, add 30 ml (1 ounce) of clean PAG Refrigerant Compressor Oil (R-
134a Systems) or equivalent to the A/C condenser core or the suction accumulator/drier inlet
tube.
5. Add 60 ml (2 ounces) of clean PAG Refrigerant Compressor Oil (R-134a Systems) or equivalent
to the suction accumulator/drier inlet tube when carrying out each of the following repairs:
�� installation of a new A/C evaporator core orifice
�� installation of a new A/C compressor pressure relief valve (19D644)
�� installation of a new refrigerant line
�� repair of an O-ring seal leak
�� repair of a charge port leak