R12 Air Conditioning questions

[gadget73]

They often mix up the LTD and LTD Crown Victoria. Totally different cars. I wouldn't neccesarily trust they didn't swap out Marquis and Grand Marquis either. Try Towncar parts.

[ford man]

Thanks guys! That makes a lot of sense. Took Gadgets advice and bought one for a '85 Town Car... last one remaining. And there was only one accumulator listed. It looked like the right one in the picture.

[ford man]

OK. So I just installed the new accumulator and orifice tube. I took 86Vicky's advice and used a orifice tube puller from Autozone. It is a free loner tool with a 21 dollar deposit that they return when you bring it back. The orifce tube looked pretty nasty. It looks like the desicant in the accumulator was starting to break up so it's good I replaced those two things.

I bought a quart of 525 r12 mineral oil and new charge caps.

Question: does anybody know what amperage the compressor should draw?

-my friend want's to check that while it's running to see if it's in specification.

[alchemist]

Reason R134a is getting high is that it too is going to be phased out, in about four years. Funny thing, it's a hydrofluorocarbon, whereas R12 is a chlorofluorocarbob. The EPA police think chlorinated hydrocarbons are bad for O3. In the upper atmosphere, they are converted to HCl.

And Gadget is correct - you always measure proper charge by either superheat or subcooling, depending on whether system has a fixed capillary tube or a TXV.

But for the absolute best charge amount, you really should pull ALL the refrigerant out, then weigh in the refrigerant. Requires either a good set of scales, or a micromotion device. Most folks have neither, so they rely on pressures. But they don't figure in wet bulb most of the time, which is essential for superheat.

[gadget73]

when I changed the tube in my car, it was also packed with sand from the dessicant in the drier. What worries me is that the sand had to go through the compressor to get the the orifice tube.

[ford man]

Reason R134a is getting high is that it too is going to be phased out, in about four years. Funny thing, it's a hydrofluorocarbon, whereas R12 is a chlorofluorocarbob. The EPA police think chlorinated hydrocarbons are bad for O3. In the upper atmosphere, they are converted to HCl.

And Gadget is correct - you always measure proper charge by either superheat or subcooling, depending on whether system has a fixed capillary tube or a TXV.

But for the absolute best charge amount, you really should pull ALL the refrigerant out, then weigh in the refrigerant. Requires either a good set of scales, or a micromotion device. Most folks have neither, so they rely on pressures. But they don't figure in wet bulb most of the time, which is essential for superheat.

We recovered the freon. My friend has a scale that he will put the cylinder on to weigh in the refrigerent. He said the scale cost 500 bucks. I'm going to tell him the total charge is 3.25lbs of r12.

[ford man]

I couldn't get any oil out of the old accumulator... is that normal?

Should I put half of the total oil charge back in? 13 ounce total charge, so add 6.5 ounces back in?

I'm going to look in my Chiltons auto ac manual to see if it has the compressor amperage spec...

[alchemist]

I couldn't get any oil out of the old accumulator... is that normal?

Should I put half of the total oil charge back in? 13 ounce total charge, so add 6.5 ounces back in?

I'm going to look in my Chiltons auto ac manual to see if it has the compressor amperage spec...

You'll never get it all out. Are you sure u lost oil? If so just get a new accumulator and orifice tube. Flush the oil from your evap and condenser using duraflush II. Add about 1/3 of total oil Charge to compressor and remainder to new accumulator.

[gadget73]

agreed, flush all of the old oil and crap out, then fill with a known amount. If there was sand in the orifice tube, you can bet there is more elsewhere anyhow. If you get hold of the factory Ford manuals (and I highly suggest owning a set just for GP), it has charts in there for exactly how much oil to add when you replace each component.

[ford man]

Ok. So I didn't flush it. The orifice was clogged a 1/3 of the way with sand not totally plugged. I did blow compressed air through the evaporator when I had the accumulator off and the oil that came out didn't look that bad.

My AC friend back blew nitrogen through the schrader valves with the schraders removed.

We added 4 ounces of 525 mineral oil to the low side of the compressor with the hose removed.

Checked the micron levels and vacuumed it down.

He added 2 lbs 10 ounces to the system measured with a digital scale. We also added dye. He wanted to undercharge it for now so I could start using the ac with less load on the compressor and move the oil around. We'll come back to it later and really dial it in with some other gauges he has. We'll charge it up more then.

It did help speed up the charging to raise the rpm to around a 1000rpm.

We are getting 38 degrees coming out the vents so far. Feels nice!

[alchemist]

Ok. So I didn't flush it. The orifice was clogged a 1/3 of the way with sand not totally plugged. I did blow compressed air through the evaporator when I had the accumulator off and the oil that came out didn't look that bad.

My AC friend back blew nitrogen through the schrader valves with the schraders removed.

We added 4 ounces of 525 mineral oil to the low side of the compressor with the hose removed.

Checked the micron levels and vacuumed it down.

He added 2 lbs 10 ounces to the system measured with a digital scale. We also added dye. He wanted to undercharge it for now so I could start using the ac with less load on the compressor and move the oil around. We'll come back to it later and really dial it in with some other gauges he has. We'll charge it up more then.

It did help speed up the charging to raise the rpm to around a 1000rpm.

We are getting 38 degrees coming out the vents so far. Feels nice!

I hope this works out for you, but if I had sand (gasp!) in my system, the whole thing would have to be flushed. Still, the orifice tube (hope you replaced it) serves as a sort of filter, before shit hits the condensor. Many times, if debris gets in the condensor, it is nearly impossible to remove because of the many bends, some of which are 180 degree. So over time, likely that stuff will make it back to the compressor. Sand is SiO2 and is pretty hard on steel. There are also aftermarket filters which can be placed right before the compressor, but you have to braze them in. No need to have undercharged the system. If you start w/oil in the compressor, it is fine. I always pull vacuum on my systems for about an hour and then close off the port to vacuum to make sure it holds. You're right, raising RPM will make suction side lower and hence, draw in the R12.

[ford man]

I hope this works out for you, but if I had sand (gasp!) in my system, the whole thing would have to be flushed. Still, the orifice tube (hope you replaced it) serves as a sort of filter, before shit hits the condensor. Many times, if debris gets in the condensor, it is nearly impossible to remove because of the many bends, some of which are 180 degree. So over time, likely that stuff will make it back to the compressor. Sand is SiO2 and is pretty hard on steel. There are also aftermarket filters which can be placed right before the compressor, but you have to braze them in. No need to have undercharged the system. If you start w/oil in the compressor, it is fine. I always pull vacuum on my systems for about an hour and then close off the port to vacuum to make sure it holds. You're right, raising RPM will make suction side lower and hence, draw in the R12.

Yes I replaced the orifice tube.

[gadget73]

its probably worse to undercharge it because it will make the clutch cycle more. Charge it the proper amount and rock and roll. If the compressor is going to blow up, its going to blow up fully charged or partially charged. I also wouldn't feel comfortable with any chance of sand or an unknown amount of oil in there either but what do I know. I've done a couple AC systems "by the book" and they haven't worked out as well as some I've seen that were just halfass Walmart conversions without a vacuum or anything. Maybe I should try halfassing one and see if it works better.

[ford man]

Halfassing it? Nah, I don't really think so...

I replaced the orifice tube. The orifice tube is a fine mesh filter. There was SOME sand desicant material, as in I could tell what it was. I replaced the dryer. I back blew the accumulator with air, it wasn't nasty.

The amount of oil we added was his guesstimate. He says when you lose freon you lose oil with it. I replaced the dryer so we added 4 ounces. I wasn't about to flush all the oil and dump the compressor out.

My AC friend wasn't particularly concerned with the orifice but said it was good I replaced those parts. He has 30 years experience.

I have no previous AC experience. I'm doing the best I can.

I guess we'll see how long the compressor lasts.

Also I'm getting 38 degrees on a partial charge. When he super heats it and sub cools it, and adds more charge, it should be even colder he says.

What temperature should I be getting?

[miamibob]

That is pretty cold! I wouldn't obsess over it. You already did the work so go with it and enjoy the cold air! As previously stated, I have seen guys do all kinds of un-natural acts and not get good or lasting results and I have seen "short cuts" last well for years.