Air conditioning experts in here please

[SVT CAMR]

After 13 years I re-installed the AC piping and compressor back into my car.

I blew all the lines out.

I have installed all new "O" Rings and 8 oz. of Pag 46 oil w/ UV into the entire system.

I believe my system can take up to 34 oz. of freon.

I bought the harbor freight evac pump #96677 that hooks up to your air compressor will pull 24 pounds of vacuum confirmed on the gauge-manifolds I also bought from there #60806.

It held all night at that pressure reading. This means the system has no leaks! I must have done something right when installing all the "O" Rings.

I have also read it is a good thing after evacuating the system for 45 minutes to close the valves turn off the vacuum pump and let it sit over night and you will eliminate all the moisture in the system.

OK I'm ready to fill it!

First I have a question. I poured 8oz. of Pag 46 oil with dye into the compressor and the low side line before final hook up. I then evacuated the system. Was this ok to do? Did I hurt the oil when evacuating the system? I assume I'm good to go and will not need freon with the oil additive in it. Please confirm this for me.

Ok so what freon to use? Should I just go with the cheapest price as long as it says 134a on the can? Or should I be looking at fancy synthetic advertising with sealer additive?

Should I just dump 34 oz. of 134a freon into the system through the manifold set?

OR should I buy 2 12oz cans and let the last (3rd) can have a preinstalled gauge on it to tweak the filling process so I do not over fill or under fill?

I understand I need to close the high side (Red) valve at the manifold and only fill through the low side (Blue) valve when adding 134a freon to the system.

My last question. Will it be ok to fill it in the ####ty cold damp weather were are having in the Chicagoland area right now?

Anybody who could answer these questions and give me more insight It will be much appreciated.

Thanks Dan

 

[laddanator]

I will tell you what I do. I just done this as I installed a KB and had the A/C unhooked to replace the condenser, dryer and lines. I pulled vacuum in the system over nite. I'm sure that's over kill but I always do that to make sure all moister is out. I always pull vacuum, then add oil. I use the Advance brand for years with no issues. 12 bucks a can I believe. Always fill through the low side and I would do it on a 77 plus degree sunny day (Don't mean a shitty rainy 77 day as the pressure in the air would be different) I found this to work best for filling. I usually don't go by the oz amount but pressure reading. I usually see 42 psi on the low side which means you're usually good to go. I do have a HVAC license and been doing A/C work forever but I'm not perfect and my method maybe different than other folks on here.

 

[STAMPEDE3]

You were fine putting the oil in first and hurt nothing.
Put in 2 cans and top off with the 3rd according to pressure.

With the cold temps pressure may be a little lower even when full but not much.
I also go with a minimum of 20° DT between outside air and what is blowing out of the vents with the system on Max high and windows down or doors open sitting still at idle but it is hotter here. You can't expect 20° DT if it is 40° outside. lol

 

[laddanator]

You were fine putting the oil in first and hurt nothing.
Put in 2 cans and top off with the 3rd according to pressure.

With the cold temps pressure may be a little lower even when full but not much.
I also go with a minimum of 20° DT between outside air and what is blowing out of the vents with the system on Max high and windows down or doors open sitting still at idle but it is hotter here. You can't expect 20° DT if it is 40° outside. lol

I wasn't sure to answer on the oil thing as I've never put it in before I pull vacuum so nice to know. Also, our compressors won't kick on if the temps are super low and below the vacuum pressure. I have jump my compressor at the low pressure switch. I do as stampede3 said, I use 2 cans and then go by pressure on the third can (not by oz).

I'm getting a cold 39 degrees out of my vents. Love seeing my breath!

 

[SVT CAMR]

Thank you so much. I'm glad the evac did not effect my oil.
dumping the 2 smaller cans and going with the 3rd can with built in gauge would be the logical way. Dose that mean I now should disconnect the manifolds at this point? Seeing I will ultimately be using the one on the 3rd can?

Is there a way to not use the gauge on the can and use the pressure reading on the manifolds. I think Lad already answered this question but I do not fully understand what would be the best reading to take off the manifolds. I really want to fill it tomorrow.

Also does anybody want to comment on the type of 134a i should use? I was at walmart and they had 3 12 oz cans (no gauge) for $6 and change each! I should jump on it. What say you?

 

[xblitzkriegx]

I will tell you what I do. I just done this as I installed a KB and had the A/C unhooked to replace the condenser, dryer and lines. I pulled vacuum in the system over nite. I'm sure that's over kill but I always do that to make sure all moister is out. I always pull vacuum, then add oil. I use the Advance brand for years with no issues. 12 bucks a can I believe. Always fill through the low side and I would do it on a 77 plus degree sunny day (Don't mean a shitty rainy 77 day as the pressure in the air would be different) I found this to work best for filling. I usually don't go by the oz amount but pressure reading. I usually see 42 psi on the low side which means you're usually good to go. I do have a HVAC license and been doing A/C work forever but I'm not perfect and my method maybe different than other folks on here.

charging by weight is the most correct way, bar none. anything else is a guess. charging by subcool will get you close but its not as accurate as weighing in the refer. there really is no excuse to guess as you can find the correct amount of refer in the FSM.

 

[SVT CAMR]

charging by weight is the most correct way, bar none. anything else is a guess. charging by subcool will get you close but its not as accurate as weighing in the refer. there really is no excuse to guess as you can find the correct amount of refer in the FSM.

very timely post. Thank you.
I was at Victor FORD today it was kind of after hours. Saw a mech. working on a mustang. I walked up and he was tearing the head off a "C" head mod motor road race car! I was oh shit. Anyway I asked him about the AC charging. He told me what ever it says to put thats what we do. If it says 2.2 pounds we put in 2.2 pounds. I was like really? What about temperature and all that. he said what ever the sticker says. This is for an empty evacuated system.

I really just know enough to be dangerous. This why I started the thread. I want to learn the right way. I wish my Dad was still alive I miss him so much. He was an AC expert. Everytime I pick up his tools I think of him.

 

[1BD9D7]

That's the one thing I have had my dad help with on both the cobras I have had, the AC! It's funny how there are certain things that dad knows all about that I don't have a clue with. I hope you enjoy that ac when it gets hot

 

[DSG2003Mach1]

with the oil you added - with everything dry did you verify the amount of oil for the compressor, lines and dryer/accumulator?

personally I wouldnt bother with a 3rd can that has a gauge when you have a manifold set...just get 3 regular cans and use your manifold set (make sure you have a can tap that hooks to your manifold hose!)

 

[SVT CAMR]

with the oil you added - with everything dry did you verify the amount of oil for the compressor, lines and dryer/accumulator?

personally I wouldnt bother with a 3rd can that has a gauge when you have a manifold set...just get 3 regular cans and use your manifold set (make sure you have a can tap that hooks to your manifold hose!)

Yes I did verify they said 8.5 oz of PAG 46. so i put 8 oz and called it good!

Now that is what I want to hear. Use the manifold and gauges. But my problem is I have no idea what are normal pressure for high and low side reading when I have enough freon and should stop filling. This is the question I need an answer to. The things is I know it is going to take a maximum of 2.2 pounds of freon but from what I understand it could also take less depending on atmosphere conditions. This is the mystery for me right now.

 

[iamtheshaner]

DSG makes a good point - the oil capacity spec is for the entire system. Your accumulator and heat exchangers will collect a huge majority of the lube oil. The general rule of thumb when it comes to servicing individual components is to replace only the amount of oil drained from the system (and the serviced components) plus an ounce or so with the understanding that you aren't realistically going to get ALL the oil out of them. If you simply replaced some o rings, lost a little oil in the process and refilled the system with the capacity spec - you are most certainly overfilled with oil.

Furthermore, if you added all of your oil to the compressor you need to turn it by hand a few times before you run the engine to confirm it won't hydrolock.

Too much lube oil is a bad thing. It negatively affects the performance and it could result in catastrophic failure because liquid cannot be compressed. Adding refer to the high or the low side is rarely an issue because it's all a vapor at normal static pressures.

DO NOT, under ANY circumstances use ANYTHING other than pure, unadulterated (no conditioners, sealers, improvers) R134a. The leak sealers in almost any brand of refer are horribly hazardous to ALL A/C servicing equipment. I have a $100 kit I use to test for these sealers and I send any job with this crap in their system down the road. It's garbage and it will contaminate every piece of equipment that ever touches your vehicle.

In regards to how to get the proper charge.....

Using cans from a part store is a guess. 1) you won't get all the refer out of all the cans unless you heat them, which is dangerous and 2) almost all the cans they sell have the garbage you don't want in them. If you have a gauge set, you can just keep charging it until your static pressures are equal to ambient temperatures. A fully charged R134a system will have static pressures of about 75psi in a 75 degree environment. Slightly undercharging will give you colder vent temps especially on a o-tube system but the compressor cycle times will be pretty short and this will eventually cause the clutch and/or coil to fail sooner.

Charging and filling oil is ideally done at the accumulator because the suction hose at the bottom of it has a metered orifice which will regulate the amount of oil allowed to enter the compressor. Because the refer is the vehicle for the oil, it (in a perfect scenario) will all collect at the accumulator like a reservoir and the orifice takes care of volume distribution. Adding oil anywhere else requires the refer to cycle it back to the accumulator and can be hard on the compressor and o tube if it's over capacity or collected in the high side trying to make it's way to the accumulator through the o tube along with a bunch of refer....

 

[SVT CAMR]

DSG makes a good point - the oil capacity spec is for the entire system. Your accumulator and heat exchangers will collect a huge majority of the lube oil. The general rule of thumb when it comes to servicing individual components is to replace only the amount of oil drained from the system (and the serviced components) plus an ounce or so with the understanding that you aren't realistically going to get ALL the oil out of them. If you simply replaced some o rings, lost a little oil in the process and refilled the system with the capacity spec - you are most certainly overfilled with oil.

Furthermore, if you added all of your oil to the compressor you need to turn it by hand a few times before you run the engine to confirm it won't hydrolock.

Too much lube oil is a bad thing. It negatively affects the performance and it could result in catastrophic failure because liquid cannot be compressed. Adding refer to the high or the low side is rarely an issue because it's all a vapor at normal static pressures.

DO NOT, under ANY circumstances use ANYTHING other than pure, unadulterated (no conditioners, sealers, improvers) R134a. The leak sealers in almost any brand of refer are horribly hazardous to ALL A/C servicing equipment. I have a $100 kit I use to test for these sealers and I send any job with this crap in their system down the road. It's garbage and it will contaminate every piece of equipment that ever touches your vehicle.

In regards to how to get the proper charge.....

Using cans from a part store is a guess. 1) you won't get all the refer out of all the cans unless you heat them, which is dangerous and 2) almost all the cans they sell have the garbage you don't want in them. If you have a gauge set, you can just keep charging it until your static pressures are equal to ambient temperatures. A fully charged R134a system will have static pressures of about 75psi in a 75 degree environment. Slightly undercharging will give you colder vent temps especially on a o-tube system but the compressor cycle times will be pretty short and this will eventually cause the clutch and/or coil to fail sooner.

Charging and filling oil is ideally done at the accumulator because the suction hose at the bottom of it has a metered orifice which will regulate the amount of oil allowed to enter the compressor. Because the refer is the vehicle for the oil, it (in a perfect scenario) will all collect at the accumulator like a reservoir and the orifice takes care of volume distribution. Adding oil anywhere else requires the refer to cycle it back to the accumulator and can be hard on the compressor and o tube if it's over capacity or collected in the high side trying to make it's way to the accumulator through the o tube along with a bunch of refer....

Great Info! Thank you
I had all the hoses and condenser compressor dryer completely removed from the car. So I know it was empty. I wound up calling the freon company and confirmed it was 99.9% pure 134a freon.

I basically did this blind and just researched the internet. I have watched my dad do this so many times at his shop. Even if I did do this successfully it will not mean anything. I felt comfortable with the process but the gauge readings is what got me. Another thing that made it harder was the cool outside temperature making all my reading low.

 

[SVT CAMR]

First thank for everyone who contributed to this thread.

I wound up re-evacuating with my bigger electric pump and was able to pull 28 pounds of pressure. (I found the fittings I needed to make it work) The other small pump would only pull 24.

I filled it today. It took all 2.2 lbs of 134a.

The pressure came in at low side 22 and high side 125 The outside temp was 52 degrees.

My thermometer came in at lowest was 36 degrees and highest was 45. Normal was 39-40. It started out at 68 degrees. The compressor was cycling on and off throughout the entire process.

Driving around with the thermostat in the vent I saw 36 degrees briefly and then it would creep to 40 then 44 then I guess the compressor would kick back on and bam 39-40 degrees again. Is it normal for the compressor to turn on an off so much?

I found multiple charts on the internet saying at 60 degree temps the pressure should be at 25-35 low side and 125-150 high side. My outside temp was 52 degrees. Comparing numbers I say I'm pretty close

How did I do?

 

[DSG2003Mach1]

if the compressor is constantly cycling, especially when set on the max setting you are likely still under charged (if you hook up your manifold set again and watch - youll see low side pressure drop, the compressor will kick off, youll see the low side pressure come up again and then the compressor restarts. If it keeps doing this at the same pressures over and over you are under charged).

as mentioned, if you had 2.2 lbs in 3 little cans you likely did not get a full 2.2lbs of charge in the system (hell you can rub your hands together to get them warm and hold the can tight and you'll see that you're getting more freon out of the can still)

another thing to add about refrigerants with leak stop and such, supposedly when a compressor fails and that garbage is in there it makes a NASTY black residue thats extremely difficult, if not impossible, to completely remove)

 

[laddanator]

56 degrees will cause the compressor to cycle. The pressure in the air must've been low. It's all in the air pressure and low pressure switch. If the outside air pressure is low, this will effect the pressure. I put freon in last year on a cold day, compressor was cycling on and off, week later, it hit 73 degrees and no more cycling.

 

[DSG2003Mach1]

^^^ could be this I suppose, cold and low pressure is a little out of my realm of experience being down here in FL lol

 

[SVT CAMR]

56 degrees will cause the compressor to cycle. The pressure in the air must've been low. It's all in the air pressure and low pressure switch. If the outside air pressure is low, this will effect the pressure. I put freon in last year on a cold day, compressor was cycling on and off, week later, it hit 73 degrees and no more cycling.

Thanks for the insight. I will report back when it hits 80 here. I will also do a visual then throw the gauges on to check pressure and also see if the compressor cycles on and off when it is in the mid 80's here.

 

[SVT CAMR]

Yesterday less than 24 hours after the victory dance. lol

I come out start the car and I hear a squeal. Long story short by the end of the day the squeal got louder trying to figure out where it was coming from. I turned on the AC compressor and it got real weird sounding. So i'm thinking it is the AC compressor pulley bearing.

This compressor has about 10K miles on it and say stored for over a decade.

Question can I just change out the pulley and bearing. The AC still blows cold.

 

[laddanator]

Yesterday less than 24 hours after the victory dance. lol

I come out start the car and I hear a squeal. Long story short by the end of the day the squeal got louder trying to figure out where it was coming from. I turned on the AC compressor and it got real weird sounding. So i'm thinking it is the AC compressor pulley bearing.

This compressor has about 10K miles on it and say stored for over a decade.

Question can I just change out the pulley and bearing. The AC still blows cold.

They make a rebuild kit with new clutches, bearings and such.

 

[SVT CAMR]

They make a rebuild kit with new clutches, bearings and such.

Lad, if it was a bad compressor how would I know? What would or would not be happening?

I don't want to out smart myself here with a $100 clutch kit change.

Earlier in the day yesterday it started out as a squeal only when giving it some gas. Then it got louder. so I walked away and later in the day it was sounding worse. So what the heck I put the AC on and it sounded like rocks in there when the clutch engages. (maybe loose ball bearings?) Do you think it is just the bearing? I would rather not change the whole thing. BTW I think rock auto sells that bearing. Also I found a compressor on craigslist right out of a 98 cobra and it has 20K on it but was removed from the car 7 years ago and stored in a finished basement. The one I have was stored in the attic for 13 years.

What would you do buy the craigslist one $80 and swap parts or just buy new kit $115.

This is bullshit! I was in the middle of my celebration and then I could not even drive the car. :fm: