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Discussion Starter #1
I have an 06 4.7 XK and want to know if the low side connection for the AC system is the one closest to the firewall as opposed to the on out by the radiator?
 

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Affirmative.
 

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Discussion Starter #4
Passenger side is blowing warmer air than the driver side. Tried to add coolant, but it pushes back out so I assume it is full and I must have a blend door issue.
 

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Passenger side is blowing warmer air than the driver side. Tried to add coolant, but it pushes back out so I assume it is full and I must have a blend door issue.
By "coolant" you mean Refrigerant/R-134a, correct?

If you're adding anti-freeze to the cooling system that has no effect on the AC system.

If you're adding refrigerant the correct way to the AC system you can easily way over charge the system and it won't be pushing refrigerant back out, so I suspect you may be doing it wrong.

If you try to add refrigerant to the High Side fitting, the pressure is higher than the can at that point, so it will back flow out of the system.

If you try to add refrigerant to either fitting while the AC system is static, i.e. not running, the pressure is greater than in the can, if the system is full, and it will back flow out of the system.

With the AC system running on its highest setting at its highest load, the low side pressure will be much less than is in the can and thus refrigerant will flow from the can into the system.

Keep in mind, even the low side pressure while its running is higher than atmospheric pressure, so any leaks in the servicing gauges/hoses and while you connect/disconnect fittings you will have some refrigerant leaking out.

It takes a good 10 minutes to empty a can into the AC system, it goes slowly.

The one side blowing warm air problem is usually one of two things, a leak in the AC system (most likely the evaporator itself) -OR- malfunctions of the air blend doors.

If you're low on refrigerant you have a leak, the charge doesn't get consumed in anyway, it doesn't go bad or break down, if you're low on refrigerant you have a leak.

If you leak refrigerant, you can also be loosing oil with the leak, that is why its important to find the leak soon and figure out if oil is getting carried with it. If you're adding refrigerant and you don't if you've lost oil or not, then add some of the "correct" oil with the refrigerant.

The low side usual has larger diameter tubes/hoses than the high side, the low side will be cool when the AC is running, the high side tubes/hoses are smaller and will be hot when the AC is running. The high side runs from the Compressor to the Condenser (in front of the radiator) to the drier/accumulator (bolted to the condenser on the Commander) then to the firewall (the expansion valve is on the firewall and both high/low side run through it, smaller is high side, larger is low side). The low side runs from the firewall to the compressor. The fittings will be on the lines, and I think on many the high side fitting is actually on the drier/accumulator (aluminum cylinder). The high/low side fittings should be different sizes to prevent hooking them up backwards.

I had a leaking evaporator, and kept adding refrigerant without oil, I ended up seizing my compressor. The evaporator will require the removal of the entire dash to replace.
 

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Discussion Starter #6
By "coolant" you mean Refrigerant/R-134a, correct? Yes

With the AC system running on its highest setting at its highest load, the low side pressure will be much less than is in the can and thus refrigerant will flow from the can into the system.
I was adding it too the low side, had the AC on to lowest setting and in recirculate mode, I did not hear compressor running, I will recheck this. It is blowing cold air on driver side, so the compressor has to be working or so I assume?

The Refrigerant I am using says it also contains oil.

The low side usual has larger diameter tubes/hoses than the high side, the low side will be cool when the AC is running, the high side tubes/hoses are smaller and will be hot when the AC is running. The high side runs from the Compressor to the Condenser (in front of the radiator) to the drier/accumulator (bolted to the condenser on the Commander) then to the firewall (the expansion valve is on the firewall and both high/low side run through it, smaller is high side, larger is low side). The low side runs from the firewall to the compressor. The fittings will be on the lines, and I think on many the high side fitting is actually on the drier/accumulator (aluminum cylinder). The high/low side fittings should be different sizes to prevent hooking them up backwards.

Yes there is a fitting Hi side on a canister near the radiator.

Thanks for the input Mongo.
 

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I hope it didn't seem like I was talking down to you, I wasn't sure if you just made a quick post and used the wrong term or if just didn't understand how it works.

2 more things I can think of.

The refrigerant and oil mix in the system to circulate it through the compressor. When the system is static, a small amount of oil will remain mixed in the refrigerant and a lot settles to the low points of the system. While its running, the circulating refrigerant will mix and circulate the oil through out the whole system evenly. So it really depends on when and where the leak is, how much oil loose. You can loose very little or a lot, depending on the circumstances.

When you buy cans of refrigerant for replacement, it will have oil in it, but different amounts. Regular cans of replacement refrigerant will have a tiny bit of oil in them, just like the refrigerant in the static system, designed to replace the oil that leaks out with the refrigerant under the best circumstances. Other cans will actual state it has a certain amount of oil in them, like 2oz of PAG46 or 2oz of PAG100, etc. Those cans are designed to inject oil into the system to replace the loss of oil from leaks.

The evaporator is low in the system and will leak oil and you can't see the oil leak because on the Commander, the drain is over top of the transmission. You symptoms do sound like a leaking evaporator, but it can be the air mix doors as well. You need to narrow it down.

When the AC system is static, pressures even out on both hi/low side.
When the AC system is running, the hi side pressure goes hi of course to like 180PSI to as much as 300PSI depending on the ambient temp. The low side, or suction side, is around 25-30PSI, the low side is the same pressure as in the evaporator, that is where the refrigerant is evaporating and making it cool.

This is why you add refrigerant to the low side, the pressure is low enough, that it will flow from the can (at a higher pressure) into the system.

You also have to have the AC at absolute MAX to charge the system. That is fan on its highest settings, recirc, with the windows open. That way the compressor is constantly running and keep low side pressure at the lowest possible, even then it will take a long time for all the refrigerant to move from can to into the system. As the pressure bleeds off the can, the refrigerant in the can has to evaporate to bring the pressure back in the can up high enough to force it into the system. You can feel the liquid in the can evaporating, NOT only getting lighter but getting cold from the evaporation.

When you run the system on low, it will turn and off, let the pressures go up and down, to only cool a little at a time. That will slow down the transfer of refrigerant from the can to a trickle only some of the time. You need to run the AC system on MAX possible to get the refrigerant move from the can.

Keep in mind, the low side, also called the suction side, is a relative pressure, its pressure is higher than atmospheric pressure. So tiny leaks, or connecting or disconnecting fittings is going to have pressure/refrigerant surge out, that doesn't mean its full.
 

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The can of r134a ie refrigerant will only fit on one side the low side. The schrader valves are not the same on low and high sides. If refrigerant is coming out and your ac is overfull you ac will not work well. Also the cans area quick somewhat fix not a substitution for proper ac work. It should be vacuumed of all refrigerant. Then oil and 134a added back in also checked for leeks. Contrary to popular belief AC systems do loose refrig without leaks not a lot but overtime it happens. I work on a fleet of over 100 large trucks that run everyday we see it all the time they last for 4 or 5 years before enough loss has occurred to require recharge.

If I were you i would use the can it may help for awhile. When I had time or money I would take it to a local shop with a 609 certified tech and the proper equipment to test and charge your system.
 

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Discussion Starter #9
I have a cheap gauge that came with one of my refill cans years ago, are they any good? I do not want to overcharge the system. Keeping the windows open is a thought, should it be in recirculate mode? Mongo,I value your information and appreciate your response not only to me, but many others on this forum. Thanks
 

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....If refrigerant is coming out and your ac is overfull you ac will not work well....
This is awful vague, and if you're stating what creek said, he was vague as well.

Refrigerant coming out of the system, may not mean its overfilled, as well, you can easily overfill an AC system without back flowing refrigerant out of the low pressure fitting.

When you connect and disconnect fittings, it is normal to get a little shot of refrigerant to vent, that is NOT overfilled. The high side, under a lot of pressure, it may seem like more than a little.

If you have cheap equipment, it may leak, even the low side (suction) pressure of the AC system is higher than atmospheric pressure, so some refrigerant forcing its way out of leaks, is NOT an overfilled system.

The real way to tell how much refrigerant in the system? A pro with expensive equipment can suck the refrigerant out and weigh it, then pump back in by weight the exact amount your AC system specifies. The other way, an amateur can do, is to use a set of Hi/Low gauges, and look at the Hi/Low pressure relationship against the specs for the AC system and the ambient temps. As well as the AC performance from the vents.

If the system is overfilled, hi side pressure will be much higher than it should be for the outside air temp, the AC performance should still be good, until the pressure gets to high on the hi side. If the system is way overfilled, than the hi and low side pressures will be too high and the AC performance will be bad. Way overfilled, the high pressure will likely cause the system to shut down, it could even cause a safety valve to vent the extra pressure.

If the system is underfilled, hi side pressures will be much lower than it should be fro the outside air temp, the AC performance may suffer, if the system is way underfilled, the low side pressure will start to go up as the hi side comes down and AC performance will greatly suffer. The system gets to low on refrigerant it won't even turn on.

...Also the cans area quick somewhat fix not a substitution for proper ac work. It should be vacuumed of all refrigerant. Then oil and 134a added back in also checked for leeks. Contrary to popular belief AC systems do loose refrig without leaks not a lot but overtime it happens. I work on a fleet of over 100 large trucks that run everyday we see it all the time they last for 4 or 5 years before enough loss has occurred to require recharge.

If I were you i would use the can it may help for awhile. When I had time or money I would take it to a local shop with a 609 certified tech and the proper equipment to test and charge your system.
He's right, the only way to even have a clue to what is going on with your AC system is too put a proper set of Hi/Low gauges on them and operate it on MAX comparing the hi/low pressures based off the ambient for the day.

You can find the gauges cheap on ebay or borrow a set, for someone that might use every couple of years, a cheap set will do.

Or take it to a pro for diagnosing. If there is a malfunction there can be all sorts of different subtle reactions the gauges will show, that require some experience to figure out.

Adding refrigerant with dye in it can help to figure out where the leak is. My leak was in the evaporator, and thus I never found the dye, but clearly had a leak.
 

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Discussion Starter #11
Put in 4/5's of refrigerant yesterday and it is now blowing cold on both sides. Will see how long it lasts. If nothing else I think it rules out the blend doors.
 

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What does 4/5's mean? 4/5's of the total capacity of the system?

Did you use refrigerant with dye in it?

Hate to say it, it sounds like a leaking evaporator. Hope I'm wrong. If it leaks down in a couple of days, and you can't find any dye, that is sounding more like the evaporator.

As you run the AC, sniff for the smell of refrigerant oil, that was my final clue that it was the evaporator, I could smell AC oil smell coming out of the vents with the AC on.

The drain for the evaporator is over the transmission, so look over the trans carefully, see if you see dye dripping down one or both of the sides.
 

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Discussion Starter #13
4/5 of a can of refrigerant. I will check vents for smell. Just checked can it did not have dye.
 

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Make sure to get a can with Dye next time you have to service, you need to find the leak. You look over the whole AC and look for the signs of leaks, some oil will leak out with the refrigerant and will leave an oily grimey residue. The dye will make it much easier to spot the leak, as well as be confident it is the AC leak and NOT an oil drop from something else that fell on the AC line or fitting.

You obviously can NOT check the evaporator burried deep under the dash. Unfortunately the Commander is a little different then others. The heater core/evaporator box has to have a drain for any water that condensates or gets into it, to drain out. Most cars this drains out the firewall, where you can see it, a little rubber fitting. This Commander instead, has drain directly out the bottom center of the box, going through a hole in the floor right over top of the transmission. There is just no way to see that drain with the trans in the way. The best you can do is hope to see a little dye running down the side of the trans (that would definitely be a leaking evaporator).
 
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