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Discussion Starter · #1 ·
Hello,

My husband and I recently inherited an 04 Town and Country, and I’ve been having issues with an AC repair.

My husband’s uncle gave me a “new”—but used from salvage—air compressor, and I installed it about a week ago. No obvious issues with that install. I also replaced the blower motor with a brand new one.

Two days ago I finally put in stop stop leak and three Freon cans as the uncle told me to do. Fluids went in fine. No leaks on the ground.

However, something is still up. When I start the air conditioning, it’s on about 68F and recycle is on. The fan strength isn’t super strong, the air starts cold and gets warmer, and a loud hissing from the dash is heard after the car is shut off. Sometimes some whining while running. Compressor also runs rough when we’re idling. The hissing only lasts a minute or so. AC always starts cold.

I bought a can of compressor oil and I have an extra Freon can, but I haven’t put them in yet.

How could I go about diagnosing this? I’m not familiar with hvac.

Much thanks
 

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It's important to get the correct amount of refrigerant into the system while keeping moisture out of the system. Did you properly vacuum pump the system down before charging? How much total refrigerant did you put in??

IIRC, the proper fill level for your van should be listed on a sticker under the hood. Suggest finding that and seeing what it indicates compared to what you put in. I believe the systems with front and rear A/C require ~2.3 lbs of refrigerant, but you should go by the factory fill sticker under the hood... assuming the system hasn't been modified. System with front only A/C will require less.

Honestly, you need a set of A/C gauges to show you low and high side pressure within the system to assist with assessment.

Though a seemingly simple topic, oil level in an A/C system can be difficult to assess following leaks and repairs.

If the system has never had a leak then the oil level within should have been correct and you would typically drain the oil out of the old compressor, measure it, and put equivalent amount of new oil in the replacement compressor.
 

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The hissing noise you hear is the refrigerant flowing as the system pressures equalize between the high and low sides of the system. It is normal for pressures to equalize when not running. It is not normal to hear it. If it is very audible it likely indicates a low refrigerant charge either due to insufficient amount when recharged or a refrigerant leak. Or it could be air and moisture in the system if you didn't vacuum the system as ScuzziOne mentions.

The best way to diagnose is a set of gauges to read the system pressures. I mean real gauges that read in PSI on both sides of the system not just Red-Yellow-Green on the low side..

I highly recommend that people not use stop leak in their A/C systems. It can only cause problems and rarely seals any leaks. Refrigerant leaks can be very minor which can be difficult to locate. They typically will not leave anything visible on the ground unless severe. The refrigerant will evaporate when not under pressure and might only leave a trace amount of oil behind. Often an electronic leak detector would be required to locate a leak that isn't so large as to be obvious.
 

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Discussion Starter · #4 ·
Hello both,

Thank you for the advice. Honestly, it’s a repair that I had to take over on my own because the uncle works nonstop 6 days a week so I didn’t want it on his plate—but I know I needed more guidance. It is what it is.

All I know is that I was told he had already drained the system, that it needed a new compressor, and that I could buy about any hose and the three cans were enough. He just gave me the stop leak. I genuinely don’t know anything about vacuuming; I assumed if it had been drained, it had been vacuumed?

Currently, 36oz have been added of the Freon and 3oz of the stop leak.

Right now I have a blue hose from Walmart that has one gauge on it. Unfortunately that’s the limit of my budget.
 

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Hello both,

Thank you for the advice. Honestly, it’s a repair that I had to take over on my own because the uncle works nonstop 6 days a week so I didn’t want it on his plate—but I know I needed more guidance. It is what it is.

All I know is that I was told he had already drained the system, that it needed a new compressor, and that I could buy about any hose and the three cans were enough. He just gave me the stop leak. I genuinely don’t know anything about vacuuming; I assumed if it had been drained, it had been vacuumed?

Currently, 36oz have been added of the Freon and 3oz of the stop leak.

Right now I have a blue hose from Walmart that has one gauge on it. Unfortunately that’s the limit of my budget.
I would go to Auto Zone and get some help they generally are very nice and you can get a loaner set of guages and check the pressure.go on U tube and search for your van and ac test there are plenty of videos that will help


Sent from my iPhone using Tapatalk
 

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I genuinely don’t know anything about vacuuming; I assumed if it had been drained, it had been vacuumed?
Any time A/C system has been "opened to the atmosphere" due to leaks and/or repair (such as compressor replacement), a vacuum pump should be used to pull a vacuum on the system after all repairs are completed in an attempt to remove all moisture prior to charging with refrigerant. If, as seemingly noted in your post, you did the compressor replacement, then you would have to be the one to pull the vacuum prior to filling.

Once under vacuum, and prior to charging, the technician will usually close-off and observe the system with a gauge to see that the vacuum holds to gain confidence that the system is sealed and that leaks have been addressed. If vacuum holds steady, then they will proceed with proper fill. If vacuum does not hold, then there is still a leak that needs to be addressed, so no point in filling until leak is found and repaired.

As noted by others, you should be able to find videos on-line that show this process.
 

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Discussion Starter · #7 · (Edited)
I went and watched good ole ChrisFix and now understand why the AC is just totally struggling. If I had known, I wouldn’t have bothered until I had more tools.

Now that I know where and how to get gauges and a vacuum: I assume the whole system has to be drained again. Is it affordable to go to a mechanic and have just the evacuation/recovery done?
 

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... a vacuum pump should be used to pull a vacuum on the system after all repairs are completed...
Once under vacuum, and prior to charging, the technician will usually close-off and observe the system with a gauge to see that the vacuum holds to gain confidence that the system is sealed and that leaks have been addressed. If vacuum holds steady, then they will proceed with proper fill. If vacuum does not hold, then there is still a leak that needs to be addressed, so no point in filling until leak is found and repaired.

As noted by others, you should be able to find videos on-line that show this process.
I never use a vacuum pump. A vacuum pump is not really needed if you know the "how to" and you don't hold an AC license.

Licensed AC technicians must use a vacuum pump and recovery system to comply with the law.

Reason I don't like creating vacuum in the system, if you have a big leak, dirt, water etc. may get into the system.
 

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Now that I know where and how to get gauges and a vacuum: I assume the whole system has to be drained again. Is it affordable to go to a mechanic and have just the evacuation/recovery done?
It's not too bad. I just did a compressor and dryer replacement this summer when my OE compressor seized. I went to Brakes Plus nearby and it was $75 to drain it and then once I got the components replaced, they took it back and vacuumed, then refilled it. The $75 covered the drain, vacuum and refill.
 

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I never use a vacuum pump. A vacuum pump is not really needed if you know the "how to" and you don't hold an AC license.

Licensed AC technicians must use a vacuum pump and recovery system to comply with the law.

Reason I don't like creating vacuum in the system, if you have a big leak, dirt, water etc. may get into the system.
The main reason for evacuating the system for more than a few minutes is to get as much moisture out as possible. Moisture can cause acid in the system. A lot can cause ice to plug the expansion valve. The drier will remove a limited amount, but it seems better to start with as little as possible.

Once you charge the system you don’t have a vacuum anymore, so I don’t understand how dirt and water would get in unless you’re charging it outside in the rain or in a dust storm.
 

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The main reason for evacuating the system for more than a few minutes is to get as much moisture out as possible. Moisture can cause acid in the system. A lot can cause ice to plug the expansion valve. The drier will remove a limited amount, but it seems better to start with as little as possible.

Once you charge the system you don’t have a vacuum anymore, so I don’t understand how dirt and water would get in unless you’re charging it outside in the rain or in a dust storm.
The main reason to keep vacuum in the system for more than a few minutes is to check for leaks. Once you reach the maximum vacuum possible for the pump you are using, you are not removing any moisture anymore.

But yes, vacuum is the best choice, but not the only one.
 

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The main reason to keep vacuum in the system for more than a few minutes is to check for leaks. Once you reach the maximum vacuum possible for the pump you are using, you are not removing any moisture anymore.

But yes, vacuum is the best choice, but not the only one.
Sorry, that’s not true. Liquid water can take awhile to boil and then migrate to the vacuum pump. With very little air in the system to move the vapor it takes awhile to remove it. Half an hour is the generally recognized minimum time.

Some people use the compressor to evacuate the system, but it’s not a very good vacuum pump. If that’s what you’re referring to.
 

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Sorry, that’s not true. Liquid water can take awhile to boil and then migrate to the vacuum pump. With very little air in the system to move the vapor it takes awhile to remove it. Half an hour is the generally recognized minimum time.

Some people use the compressor to evacuate the system, but it’s not a very good vacuum pump. If that’s what you’re referring to.
No, there is another way, better than using a vacuum pump, but AC licensed technicians are not allowed to use this technique.

Once the max vacuum is reached, nothing else is coming out, it doesn't matter how long you keep the vacuum pump running.
 

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No, there is another way, better than using a vacuum pump, but AC licensed technicians are not allowed to use this technique.

Once the max vacuum is reached, nothing else is coming out, it doesn't matter how long you keep the vacuum pump running.
I’m sorry to beat a dead horse, but if you’d ever worked with high vac systems you’d know differently. The vacuum achieved by a mechanical vacuum pump is nowhere near a total vacuum. If you put a glass of water in a mechanically-pumped vacuum you’ll see that it doesn’t flash to vapor, it boils until it’s all gone. Mechanical gauges can’t come close to indicating a total vacuum — it takes an ion gauge to come close. Lots of outgassing takes place.

The AC world knows that you need to pump for quite awhile — it’s easy to find sources that say that.

Why keep your “other way” a secret?
 

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I never use a vacuum pump. A vacuum pump is not really needed if you know the "how to" and you don't hold an AC license.
I am curious to hear about your "how to" method. Whatever it is I am sure that it is leaving significant amounts of moisture and contaminants in the system.

Licensed AC technicians must use a vacuum pump and recovery system to comply with the law.
I have been certified by MACS for thirty years. The EPA law concerns proper recovery and handling of refrigerants. It does not specify best practices for repair.

Reason I don't like creating vacuum in the system, if you have a big leak, dirt, water etc. may get into the system.
Yeah, and you might even draw some insects into the system as well, huh? lol

If you are charging a system that has a large leak either you did not diagnose it properly or you did not put it together properly. A large leak would be evident almost immediately when it is not possible to pull a good vacuum. I prefer to charge systems that don't have a large leak.

If you don't properly evacuate an A/C system I guarantee that you are introducing more contaminants, and especially more moisture, into the system than what might possibly be drawn in via a leak regardless of size.
 

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The main reason to keep vacuum in the system for more than a few minutes is to check for leaks.
No it is not. The main reason to pull a vacuum is to remove contaminants from the system in the form of air and moisture. This is done by bringing the pressure below atmospheric and boiling the water out of the system.

Using the vacuum to check for leaks is a secondary benefit to pulling a vacuum on an A/C system.

Once you reach the maximum vacuum possible for the pump you are using, you are not removing any moisture anymore.
Once again, you are incorrect. Imagine boiling a pot of water on the stove. When the temperature reaches 212F and the water begins to boil, all of the water does not turn to vapor at once. It takes some time for all the water to change state. In the same way, it takes some time to boil most of the water out of an A/C system under vacuum.

But yes, vacuum is the best choice, but not the only one.
I can't wait to hear about your method.
 

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No, there is another way, better than using a vacuum pump, but AC licensed technicians are not allowed to use this technique.
This is the third time you have bragged about your superior technique. Please enlighten the rest of us with your wisdom. I am on the edge of my seat in anticipation.

Once the max vacuum is reached, nothing else is coming out, it doesn't matter how long you keep the vacuum pump running.
You really don't understand basic physics, do you?
 

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I’m sorry to beat a dead horse, but if you’d ever worked with high vac systems you’d know differently. The vacuum achieved by a mechanical vacuum pump is nowhere near a total vacuum. If you put a glass of water in a mechanically-pumped vacuum you’ll see that it doesn’t flash to vapor, it boils until it’s all gone. Mechanical gauges can’t come close to indicating a total vacuum — it takes an ion gauge to come close. Lots of outgassing takes place.

The AC world knows that you need to pump for quite awhile — it’s easy to find sources that say that.

Why keep your “other way” a secret?
Actually, I am ASME External Pressure Vesel Certified, which is something a littlle AC technician can only dream about.

Note: External Pressure is the correct terminology.

Of course the vacuum achieved by that little AC vacuum pump is not even close to total vacuum, the aluminum lines would quickly colapse if that little AC vacuum pump were more powerful.

I have been certified by MACS for thirty years.

If you are charging a system that has a large leak either you did not diagnose it properly or you did not put it together properly. A large leak would be evident almost immediately when it is not possible to pull a good vacuum. I prefer to charge systems that don't have a large leak.

If you don't properly evacuate an A/C system I guarantee that you are introducing more contaminants, and especially more moisture, into the system than what might possibly be drawn in via a leak regardless of size.
That's exactly my point!

I've never said you should charge a system with a big leak.

If you are indeed MACS certified, you can not use this technique. You should know it, but you are not allowed to use it.
No it is not. The main reason to pull a vacuum is to remove contaminants from the system in the form of air and moisture. This is done by bringing the pressure below atmospheric and boiling the water out of the system.

Using the vacuum to check for leaks is a secondary benefit to pulling a vacuum on an A/C system.



Once again, you are incorrect. Imagine boiling a pot of water on the stove. When the temperature reaches 212F and the water begins to boil, all of the water does not turn to vapor at once. It takes some time for all the water to change state. In the same way, it takes some time to boil most of the water out of an A/C system under vacuum.



I can't wait to hear about your method.
You are not reading my post, I've said
The main reason to keep vacuum in the system for more than a few minutes is to check for leaks. You don't need to keep a vacuum too long to evacuate the system.

You can not check for leaks while the pump is running, so checking for leaks is not a secondary benefit.

You don't have a glass of water to boil inside the system, just traces of water wich doesn't takes long to "boil".

Once you reached the vacuum of 29.92 HG, you only need one minute to evaporate any amount of water in the system.

Again, water vapour obtained after you reach the maximum vacuum achieved by your little vacuum pump will not be removed from the system, it will transform back to water once the vacuum is broke.

In case you don't understand this little fact, once your vacuum pump reach it's maximum, gases will stop flowing out of the system, it will be worthless to keep the pump running trying to keep removing humidity.


You really don't understand basic physics, do you?
I do, you probably don't.

Have a nice day! 😁
 

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Of course the vacuum achieved by that little AC vacuum pump is not even close to total vacuum, the aluminum lines would quickly colapse if that little AC vacuum pump were more powerful.
You’re stubborn. And that statement proves that you don’t know what you’re talking about.
 
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