Recharging A/C System

[SignatureSeriesOwner]

Hi all,

In the midst of doing my dash repairs, I’m also recharging my air conditioner. I’ve pulled a vacuum on it overnight, and over the last two hours I’ve not lost any vacuum.
My question is...do I attach the can to the fitting directly on the head of the compressor? The other fitting is on the ‘barrel’ of the discharge line.

I’m looking at the service manual, and it’s telling me I need a special adapter that I’m sure is long since unobtainable to screw into the back of the compressor. Please tell me there is another way.

 

[rkrochen]

Glad you asked. If you attach the can to the wrong place it can literally explode in your hands. You need to attach it to the suction side before the compressor not to the head or high side.

 

[rkrochen]

Glad you asked. If you attach the can to the wrong place it can literally explode in your hands. You need to attach it to the suction side before the compressor not to the head or high side.

Let me clarify this is specific to the small cans of Freon.

 

[SignatureSeriesOwner]

I’m not seeing a ‘suction’ fitting on the low side. Just the two fittings on the compressor, and the line from compressor to condenser.

 

[rkrochen]

It’s usually located close to the compressor. What are using to fill the system with.

 

[SignatureSeriesOwner]

Sorry guys, I’m an absolute idiot. If it was a snake it would have bit me.

Currently have three cans in. Need to adjust the ac belts once the engine cools a bit because those puppies are hating life right now. Rear belt is tight-ish, but the front belt has 1” or so of deflection and is slapping around everything. It looks like the alternator is maxed out, so I might just have to replace all the belts.

 

[Davea Lux]

You may be headed for a disaster here. Are you installing R-12 or R-134a? The RV2 compressor on your vehicle came set up for R-12. It is a fairly involved process to convert to R-134a. If the system was previously converted to R-134a, your main concern will be to be sure that the compressor has adequate oil. Evacuating the system boils off some or all of the oil in the compressor and the attached appliances. Anytime the system has gone "flat", read discharged, or a refrigerant line has been disconnected, the filter dryer should be replaced. The system is then completely evacuated of all oil and residual refrigerant. The system then needs to be recharged with the proper amount of the appropriate refrigerant oil. Failure to recharge the system with oil will result in a compressor burn out in short order after the refrigerant is added.

If this system still had R-12 oil in it and you recharged the system with R-134a, any oil in the system has now turned to a gelatin roughly resembling yellow snot, R-12 oil does not play well with R-134a as the two are not chemically compatible. This snot clogs up the expansion valve, evaporator, condenser and filter dryer and is useless as a lubricant. Compressor will die quickly. The old R-12 oil all needs to be removed as part of the conversion process. Normally this can be done by leaving an evacuator on the system for several hours. The old oil will boil off to eliminate compatibility issues with the updated refrigerant. It is recommended that all of the o-rings be replaced with the green ones that are designed for R-134a. The filter dryer should also be replaced and it is also recommended that the low side hoses be replaced with the high density rubber and updated fittings to prevent the R-134a from leaking out. The R-134a gas molecule is significantly smaller in size than the R-12 molecule and is prone to leaking thru low density hoses and o-rings. The conversion from R-12 to R-134a is usually best left to a professional.

Dave

 

[SignatureSeriesOwner]

Hi,

I’m keeping R-12 in it. System was overhauled in the late 80’s it looks like. Four Seasons compressor, Dayco A/C lines, replacement drier and EXV.

I wanted to verify it’s operation, so I pulled a vacuum overnight, and let it sit for three hours while I went out to check for leaks. Still at -29 after three hours, so I charged it up. Cold as a mutha in here.

I agree, I should have changed the drier. I have about 8 cars that run R-12 still, and will not convert unless there is a catastrophic failure. I’ve serviced many an automotive AC system, but the few times I’ve been in a situation where I’ve checked for oil weight after vacuuming down, it’s all still remained in the compressor. Sure, you’ll lose a bit, but looking at all my equipment, there’s no oily residue on the vent of the vacuum pump, or on any of the lines on my manifold set. I’ll take my chances, everything is performing well, but I’m still about 3/4 of a pound low, going off my gauges.

What’s a full charge on this? There’s no sticker anymore. Basing it off my Continentals from the same decade, I’d wager around 4 pounds?

 

[Davea Lux]

Hi,

I’m keeping R-12 in it. System was overhauled in the late 80’s it looks like. Four Seasons compressor, Dayco A/C lines, replacement drier and EXV.

I wanted to verify it’s operation, so I pulled a vacuum overnight, and let it sit for three hours while I went out to check for leaks. Still at -29 after three hours, so I charged it up. Cold as a mutha in here.

I agree, I should have changed the drier. I have about 8 cars that run R-12 still, and will not convert unless there is a catastrophic failure. I’ve serviced many an automotive AC system, but the few times I’ve been in a situation where I’ve checked for oil weight after vacuuming down, it’s all still remained in the compressor. Sure, you’ll lose a bit, but looking at all my equipment, there’s no oily residue on the vent of the vacuum pump, or on any of the lines on my manifold set. I’ll take my chances, everything is performing well, but I’m still about 3/4 of a pound low, going off my gauges.

What’s a full charge on this? There’s no sticker anymore. Basing it off my Continentals from the same decade, I’d wager around 4 pounds?

Single or dual evaporator?

Dave

 

[SignatureSeriesOwner]

Hi,

Single Evaporator. Wish I had dual units. That’s a really cool setup.

 

[Davea Lux]

Hi,

Single Evaporator. Wish I had dual units. That’s a really cool setup.

R-12 charge is 3#2oz to 3#6oz for single system. Check your sight glass on the dryer, add refrigerant until the sight glass runs free of bubbles. Our old school guys would add another 4oz when a clear sight glass was achieved. Note it is very important the the clutch fan is in good working order, the condenser if free of debris, fan shroud in place and system blower is at max speed when using this method.

Dave

 

[SignatureSeriesOwner]

Fan clutch is on order. It’s shot. Takes no effort to spin it at all.

 

[Davea Lux]

Fan clutch is on order. It’s shot. Takes no effort to spin it at all.

You won't get enough air flow to properly evaluate the state of charge until a new one is installed. Wait till that is done to finish the charging process.

Dave

 

[SignatureSeriesOwner]

I ordered the thermal one, as that’s what tends to be on all of them. There was a non thermal option, that’s not correct, is it?

 

[Davea Lux]

I ordered the thermal one, as that’s what tends to be on all of them. There was a non thermal option, that’s not correct, is it?

The correct unit is the thermal one for most applications with A/C. What year is this car?

Dave

 

[SignatureSeriesOwner]

1971. AC and AM radio are about the only options it’s got.

 

[Davea Lux]

1971. AC and AM radio are about the only options it’s got.

Thermal unit.

Dave