Complete A/C system replacement? (1 Viewer)

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@culturedredneck You didn't mention in your step by step if youre purging the yellow line before you charge the refrigerant through it. If you didn't, you put air and moisture back into the system. I actually did this once myself and the temp ran about 57 degrees. It's not a ton of air/moisture, but enough to undue all your hard vacuum work.

Your question about the PAG oil causing the mediocre temps is valid it COULD, as too much PAG will prevent efficient temp transfer, but as long as you emptied the compressor, and don't have like 20 oz of PAG running around in the system, that's probably not the issue.
 
@flintknapper You sir are a saint. Thank you for taking the time to type all that out, especially on a Saturday. I had already done a little work previous to reading your post, but for the most part I followed it to the letter.

The good news is that I have AC in my car! Its a weird feeling riding around in the summer with the windows up! The less-than-good-news is that its still not as cold as I think it should be based on my research. Currently in the peak of the heat today (about 87F with 48% humidity) the lowest it registered was about 49F at the center vent. It would cycle between about 49 and 54 consistently. Now, that was still pretty chilly, but based on what I've read its not as cold as it should be, and I want it to function as intended. Please correct me if Im wrong on this, and these temps look correct.

If I am correct, and it could be colder, then I think the problem is the following.

1. I didn't vacuum long enough. Because this was a learning process there were several instances where I pulled a vacuum, messed something up and pulled again. It always pulled to -30, but I think that what I really needed to do was pull to -30 and leave it for like 5 hours to get rid of all of the moisture and air in the system.

2. As @mellowdave has said, I probably could have been better about purging the lines of all air. I attempted this, but may not have been as careful as I could.

@flintknapper I would love to know what you think about this, and especially what the normal vent temp should be. I can always buy some more freon and try again tomorrow. Third time's a charm! (hopefully)

Meanwhile, thanks to everyone who has chimed in. It goes without saying that this community is invaluable.

P.s. @mudgudgeon Do it! The repairs themselves only took about a day and were straight forward. If I had to do it all over again I could probably do it in less time than that, and Im no mechanic.
 
culturedredneck said:
@flintknapper You sir are a saint. Thank you for taking the time to type all that out, especially on a Saturday. I had already done a little work previous to reading your post, but for the most part I followed it to the letter.

The good news is that I have AC in my car! Its a weird feeling riding around in the summer with the windows up! The less-than-good-news is that its still not as cold as I think it should be based on my research. Currently in the peak of the heat today (about 87F with 48% humidity) the lowest it registered was about 49F at the center vent. It would cycle between about 49 and 54 consistently. Now, that was still pretty chilly, but based on what I've read its not as cold as it should be, and I want it to function as intended. Please correct me if Im wrong on this, and these temps look correct.

If I am correct, and it could be colder, then I think the problem is the following.

1. I didn't vacuum long enough. Because this was a learning process there were several instances where I pulled a vacuum, messed something up and pulled again. It always pulled to -30, but I think that what I really needed to do was pull to -30 and leave it for like 5 hours to get rid of all of the moisture and air in the system.

2. As @mellowdave has said, I probably could have been better about purging the lines of all air. I attempted this, but may not have been as careful as I could.

@flintknapper I would love to know what you think about this, and especially what the normal vent temp should be. I can always buy some more freon and try again tomorrow. Third time's a charm! (hopefully)

Meanwhile, thanks to everyone who has chimed in. It goes without saying that this community is invaluable.

P.s. @mudgudgeon Do it! The repairs themselves only took about a day and were straight forward. If I had to do it all over again I could probably do it in less time than that, and Im no mechanic.
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Well.....you're getting there, and I applaud you for sticking with it.

To address a few of your questions, yes...I believe there is still some additional cooling to be had. But we must be careful NOT to assign a specific target number that applies universally. There are just too many variables (weather conditions, vehicle condition, etc). Generally speaking, if you can achieve vent temps 35°-40° F. degrees below ambient you're doing pretty darn good.

Vent temps are going to fluctuate with conditions of course, but the 'spread' will normally be fairly consistent. If you were sitting in traffic, idling on hot blacktop with 95° F. ambient, I'd be tickled to death to see 50°-55° vent temps (fan on high w/recirculate). Now...lets change the environment: Nightfall, 80° F. ambient, highway speed 70 mph. If I didn't see 40°-43° F. vent temps, I would be looking at the engine cooling system. We expect the actual 'vent temperature' to change, but I also want to see that 'spread' (difference between ambient and vent temp) maintained (roughly 35-40°, sometimes a bit more).

But this is isn't always practical, one vehicle to the next, so I throw those numbers out there as a general guideline only. You might have a perfectly charged, leak free system, but if your engines cooling system is not 'tip-top', then your A/C will suffer for it. A perfectly charged and functioning system A/C system only insures that a good heat exchange is 'possible'. IF there isn't sufficient air moving through the condenser, performance will be poor (or at least not as good as it could be). If your fan clutch is weak, it not only isn't pulling all the air it could through the condenser, but also not your radiator. Once the engine/trans/radiator and engine compartment get good and heat soaked, it will make it tough for your A/C system to work at its best.

Solar gain (sunshine coming in through windows) will have an effect. There are lots things working with (or against) your A/C system depending on circumstance. So....chasing down those last few degrees of cooling can be challenging, but usually worth it.

Back to YOUR vehicle: Yes too much oil in the system will have an effect on its ability to transfer heat, but a small amount (an ounce or so over) isn't going to be that concerning. Moisture and air are to be avoided. Likewise flushing agent. Many folks suppose they removed all the flushing agent because they see none while blowing compressed air through the lines/components. And depending upon which agent you used (some evaporate quickly) you may of may not have it all out.

When blowing out the lines it is important to block the escape route of line/component with your finger and let pressure build up. Using a blowgun with a rubber tip apply air at one end while blocking the other, then quickly remove your finger. This will cause a very forceful release of the air pressure and will carry any liquid and debris with it.
Once you no longer see a 'mist' discharging, you should be good to go. But make sure to drain your air compressor frequently as you go, water from the compressed air will build up in it. We don't want that in the lines or components.

Pulling a vacuum: It is easy to think that if your compound gauge is showing 28-30 inHg, that you have satisfied the need to have a vacuum on the system. And for that purpose alone, you have. BUT...the other purpose for pumping the system down (and the MOST IMPORTANT) is to remove moisture. This can take time. I won't even consider pumping down a system for less than an hour, usually two and more if the system has been flushed or I suspect some moisture might still remain (turn your manifold valves off with the pump still running when you are ready to quit). If you use a traditional pump, be sure to use FRESH pump oil each time you pull a vacuum.

Purge your lines: ALWAYS purge your lines each time you connect to a can of refrigerant and before opening any valves. If you don't you are introducing air and moisture right back into the system you just worked so hard to remove it from. Small amounts....yes, but we don't need any. Do it right!

So...with a new or completely evacuated system, we need:

1. A CLEAN system (all lines and components)
2. A leak free system. For obvious reasons.
3. Properly working components (TXV, Condenser, Evaporator, Compressor, Clutch, Pressure switches)
4. Proper charge of oil and refrigerant.

If you do this....you will have a properly operating, long lasting A/C system. Don't take short-cuts, its not worth it.

Putting in an all new system or charging a completely evacuated system is the easiest of all scenarios. We are dealing with known quantities and components.

Diagnosing or charging a faulty/partially charged unit is where things get dicey and you need to know your stuff.

Folks, when doing A/C work, go slow, be thorough, do it ONCE (the right way) and you will be rewarded, I promise.
 
mudgudgeon said:
@flintknapper great work on the succinct write up and instructions!

when purging before charging with refrigerant, would you expect to visibly see a little refrigerant escaping?
Click to expand...


Yes Sir.

You'll see it, feel it, hear it.

Just a tiny bit is sufficient, we just want to get all the air and moisture out of the hoses. Easy to do, just go slowly. Don't want to disconnect a line full of refrigerant under pressure!

Safety glasses should be used.
 
@flintknapper Thanks! It doesn't sound like I'm too far off, but Im going to give it another shot today and see if I cant get those last few degrees by following your instructions to the letter. And if I cant, maybe then ill look at my cooling system or other possibilities.

Is there any way to know when all moisture has left the system? I noticed that there appears to be a little bit of steam coming from the exhaust port on the vacuum pump. Does that have anything to do with moisture being pulled out or burned off?
 
culturedredneck said:
@flintknapper Thanks! It doesn't sound like I'm too far off, but Im going to give it another shot today and see if I cant get those last few degrees by following your instructions to the letter. And if I cant, maybe then ill look at my cooling system or other possibilities.

Is there any way to know when all moisture has left the system?

Nothing definitive (without a micron gauge). Since you've had the system charged at least once now and run it for awhile, we can expect that any residual flushing agent will be expelled with the refrigerant when you evacuate. Same thing with most of any air and moisture present in the system. Since you won't be leaving the system open to atmosphere for long, you should be able to pump the system down for 90 minutes and be O.K.

Remember, to shut your valves off (at the gauge manifold) while the pump is still running right before you shut it off. Use FRESH pump oil each time you pull a vacuum on the system.

We will be left with two unknowns at this stage in the game.

1. How much compressor oil you have left in the system (since you will have evacuated once or twice).
2. Whether or not the desiccant in the drier is still any good. (I normally replace each time the system has been opened, but yours might still be good.

I noticed that there appears to be a little bit of steam coming from the exhaust port on the vacuum pump. Does that have anything to do with moisture being pulled out or burned off?

Yes, and it will diminish as the system clears out....BUT it might not ever stop completely depending upon the temperature and humidity at the time. You might continue to see a small amount of steam looking vapor from that port because it is being released by the pump oil and the temperature difference (like being able to see your exhaust on a cold day). So don't continue to pump the system down based on that. But it is a good sign that the pump is working well.
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Expand to see reply ^^^^^^^^^^
 
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culturedredneck said:
@flintknapper Thanks! It doesn't sound like I'm too far off, but Im going to give it another shot today and see if I cant get those last few degrees by following your instructions to the letter. And if I cant, maybe then ill look at my cooling system or other possibilities.

Is there any way to know when all moisture has left the system? I noticed that there appears to be a little bit of steam coming from the exhaust port on the vacuum pump. Does that have anything to do with moisture being pulled out or burned off?
Click to expand...

Absolutely EVERYTHING @flintknapper said is spot on, obviously. I would 100% take a look at the cooling system. The vehicle doesn't require a lot of additional cooling to run properly in all but extreme environments, so many times you may not even realize that the cooling system isn't working optimally. The fan clutch is a common culprit, it will spin freely when it shouldn't. SInce the truck pretty much stays cool on the merit of the liquid, you don't even notice it isnt pulling additional air through the radiator/condensor combo til your AC gets warm at stop lights, etc.

I was really seeing it in the heat soak that @flintknapper mentioned, when it was really hot ambient, my AC would really take forever to cool down, and would go right back up once I came to a stop, or slowed down. New fan clutch fluid, and some work with the gaskets and insulating materials and mine is 50 degrees idling on a hot day. My next efforts are going to reduce heat gain through the windows and the roof, as well as through the transmission tunnel, and rear quarter panels.
 
Update on the AC:

I completed another evac and refill, this time following ALL of the directions laid out by @flintknapper. First thing I noticed when I took better care to bleed the lines before refill was that when I charged the high side this time, the system sucked in the can SUPER fast. I'd say less than a minute or so. Before it was much more of a struggle to get the first can in. All in all, the rest of the 30 OZ went in smooth and steady. I weighed it in this time instead of guessing.

Now, the process was improved, but the results... not so much. It actually appears to be running just slightly warmer than before. The coolest Ive been able to get it 49F (on a cool 75F evening) with the average cycling between 50-54F. On the previous fill, I saw it dip down to 47.

I understand that adding more freon to achieve to cooler temp is flawed logic, but is there a way to check the system to see if the right amount is in there? The FSM gives some ways using the sight glass, but my sight glass is pretty gummed up and not easy to see through.

Its funny, because if i just dropped it off at a mechanic to have the ac fixed, Id probably be satisfied with how cold it is. But because i'm doing it myself Im obsessing about it being as cold as it can possibly be!
 
culturedredneck said:
Update on the AC:

I completed another evac and refill, this time following ALL of the directions laid out by @flintknapper. First thing I noticed when I took better care to bleed the lines before refill was that when I charged the high side this time, the system sucked in the can SUPER fast. I'd say less than a minute or so. Before it was much more of a struggle to get the first can in. All in all, the rest of the 30 OZ went in smooth and steady. I weighed it in this time instead of guessing.

Now, the process was improved, but the results... not so much. It actually appears to be running just slightly warmer than before. The coolest Ive been able to get it 49F (on a cool 75F evening) with the average cycling between 50-54F. On the previous fill, I saw it dip down to 47.

I understand that adding more freon to achieve to cooler temp is flawed logic, but is there a way to check the system to see if the right amount is in there? The FSM gives some ways using the sight glass, but my sight glass is pretty gummed up and not easy to see through.

Its funny, because if i just dropped it off at a mechanic to have the ac fixed, Id probably be satisfied with how cold it is. But because i'm doing it myself Im obsessing about it being as cold as it can possibly be!
Click to expand...

Were you able to get it any cooler when driving? I know on mine it won't reach the very coldest temps unless the vehicle is moving. Also have you checked the heater valve to confirm no warm water is flowing which will prevent you from reaching the coldest temps.
 
Zach- It doesn't really get much cooler when driving. Maybe a degree or two, but I've tested it at highway speed and it stays in the 49-52 range. And yes, just replaced my heater valve with a new OEM one and have adjusted the cable to its max length. Even removed the cable so the HCV can achieve its maximum throw, thereby cutting off all warm water.
 
Im also noticing some engine hesitation on acceleration after this last evac/ refill. Wonder if I evac'd too much oil and the compressor is putting a strain on the engine? Didn't notice it before this last go round....
 
What are your gauge readings (high side and low side)?

Now that we have something to work with ( a known method of installation), we can try to 'fine tune' (diagnose) the system via the gauges.

Need to know:

Ambient temp at time of reading
Readings for High and Low side (at idle)
Engine temperature (if you have a way of providing that)



What are you using to measure the vent temps?

In the meantime....just for a quick diagnostic test: Start your vehicle, let it get up to operating temperature, let it idle, with windows rolled up, A/C set to MAX and recirculate, let the system run until you see the vent temp stabilize, take that reading, then take a water hose and 'mist' water into the grill opening for about 3-4 minutes and look at the vent temp, record that and let me know what you find.
 
@flintknapper Just returned from performing these checks.

At idle, when the car has reached its operating temp, the AC is blowing about 52-53F and stays there. Car is in the shade and its 81 degrees outside. I misted the grill with a hose for 3 min and that brought it down to 47F, lowest I've seen so far. Interestingly, it also brought the high side pressure down.

At operating temp and idle the low side gauge reads 40 and the high side reads 280. Inside vent temp 53.
After misting, the low side reads 30 and the high side reads 190. Inside vent temp 47.

Im using a digital cooking thermometer stuck in the vest to test vent temp. A 10$ one from walmart. Currently I don't have a way of reading an exact engine running temp, although this is wanting to make me invest in something... temp gauge usually stay about half way.
 
culturedredneck said:
@flintknapper Just returned from performing these checks.

At idle, when the car has reached its operating temp, the AC is blowing about 52-53F and stays there. Car is in the shade and its 81 degrees outside. I misted the grill with a hose for 3 min and that brought it down to 47F, lowest I've seen so far. Interestingly, it also brought the high side pressure down.

At operating temp and idle the low side gauge reads 40 and the high side reads 280. Inside vent temp 53.
After misting, the low side reads 30 and the high side reads 190. Inside vent temp 47.

Im using a digital cooking thermometer stuck in the vest to test vent temp. A 10$ one from walmart. Currently I don't have a way of reading an exact engine running temp, although this is wanting to make me invest in something... temp gauge usually stay about half way.
Click to expand...

OK, looks as if your low side is slightly high and your high side is definitely high. Two most likely reasons are 'System slightly overcharged with refrigerant' or 'insufficient air flow across the Condenser'. By misting the front of the vehicle you brought the pressure down (almost exactly) where we would like to be at idle at that ambient....without artificially cooling the system.

So...just for now...lets not fiddle with the system charge (though we might end up releasing a small amount of refrigerant before we're through).

Let's turn our attention to your engine temperature and the condition of your fan clutch. You may already be aware that the factory temperature gauge has a huge dead spot in it. Your engine temp could be well over 210° F. and you wouldn't know it. IF you know what fan clutch you have and how old it is....that would be helpful information. Can you hear your fan pulling air (slight roar) at engine start up (engine cold)? We really need some way to measure your engine coolant temps as well. I have a suspicion there may be room for improvement there before we go back to looking at the A/C system.

Also, make sure all your A/C-Heater positions (blend doors) are functioning correctly. Run them through each position and feel the outlets for air flow (without substantial leakage to the others).
 
@flintknapper Well, I bought a scangauge 2 today so I can tackle this problem and the check engine light that popped on. I'll use it to get an engine temp. Should this be at idle or driving?

No idea about how old the fan clutch is, but I'm not opposed to replacing it. I like preventative maintenance.
 
culturedredneck said:
@flintknapper Well, I bought a scangauge 2 today so I can tackle this problem and the check engine light that popped on. I'll use it to get an engine temp. Should this be at idle or driving?

No idea about how old the fan clutch is, but I'm not opposed to replacing it. I like preventative maintenance.
Click to expand...

ScanGauge II is EXCELLENT. You will want to look at temperatures both at idle and while driving. Do this in a variety of conditions and watch for temperature spikes and patterns (even temperature, hotter on highway, hotter at idle in traffic, A/C drives up temperature 10 degrees or more).

Good choice...to monitor your vehicle, now we can get some definitive answers. I love my Scangauge.
 
Im with @flintknapper here, your change in readings indicates that better performance is to come from your cooling system. Im in the exact same boat. Likely your fan clutch doesn't need replacing, but you can definitely upgrade the oil in it to get it to draw more air. They come with 3000 CST, Joey at Wits End sells them with 15,000 CST.
 
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