possible A/C prob
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Joined: May 2001
Posts: 2,121
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From: Indian Land SC
[QUOTE]Originally posted by Slows2k
We really are grasping for an answer at what could be the problem. A faulty expansion valve, blocked air flow to the condensor, faulty fan controls, the list goes on.
We really are grasping for an answer at what could be the problem. A faulty expansion valve, blocked air flow to the condensor, faulty fan controls, the list goes on.
Joined: Oct 2000
Posts: 986
Likes: 10
From: 12m SW of Glen Rose, Tx
[QUOTE]Originally posted by Slows2k
BTW, I've never had a honda evaporator ice in any model car in the past 5 years, And have seen plenty of low systems. It's still a possiblity, bu the AC system is complicated enough to daignose and repair when you are working on the car, doing the same online makes the process even more difficult.
BTW, I've never had a honda evaporator ice in any model car in the past 5 years, And have seen plenty of low systems. It's still a possiblity, bu the AC system is complicated enough to daignose and repair when you are working on the car, doing the same online makes the process even more difficult.
Joined: Oct 2000
Posts: 986
Likes: 10
From: 12m SW of Glen Rose, Tx
[QUOTE]Originally posted by modifry
I think (know) you're off base here and I'm going to have to disagree with much of your post.
First, I've had too many cars over the years that had freezing evaporators, and they all got "fixed" (if only temporarily) by adding freon.
I think (know) you're off base here and I'm going to have to disagree with much of your post.
First, I've had too many cars over the years that had freezing evaporators, and they all got "fixed" (if only temporarily) by adding freon.
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Joined: May 2001
Posts: 2,121
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From: Indian Land SC
^
It's been over 30 years for me, and I never had the benefit of a college education, but I seem to remember something about "gas laws" and "gas constants" from high school. Avagadro comes to mind, as does Boyle, but I couldn't say why.
One of those laws states that in a closed system the gas pressure of any liquid is directly proportional to temperature ONLY. The amount of liquid in the system is irrelevant, as long as liquid is present. If more gas is added, the pressure rises microscopically, causing more gas to condense, which lowers the pressure, and the system equalizes at the same pressure as before.
As long as there is one drop of liquid in the system the pressure will remain constant (assuming constant temperature). That's why I say nearly all the refrigerant will have to escape to activate the low pressure switch. A system that is normally charged with 2 lbs of refrigerant (typical for cars?) will still have liquid present with only a few ounces of refrigerant in the system.
If you look at your refrigerant gauges you will see a temperature scale around the dial, with a different temperature for each refrigerant. The pressure in the system will exactly match the temperature of the system, which if it's had time to stabilize at ambient, means the gauge will indicate ambient temperature as long as there is any liquid in the system.
Yes, pressure will rise as you fill a system, but there will be a time when pressure stops rising even though you add more refrigerant. This is why refrigeration systems are charged by the weight of refrigerant (even though it's much harder to measure) and not the pressure.
That's also why it's difficult to fill a system without running it. Once the liquid in the system reaches ambient temperature (same temp as the bottle) you can't put any more refrigerant in, because the pressures are the same. So you either have to dump a bunch of liquid in quick before it has a chance to heat up, or you have to run the system and add additional gas into the low side.
Think about this - if you can tell the state of charge by measuring pressure (like the pressure switch needs to do), you could simply connect your gauges to a static system, take a reading, and announce "it's 8 ounces low". But you can't.
.
It's been over 30 years for me, and I never had the benefit of a college education, but I seem to remember something about "gas laws" and "gas constants" from high school. Avagadro comes to mind, as does Boyle, but I couldn't say why.
One of those laws states that in a closed system the gas pressure of any liquid is directly proportional to temperature ONLY. The amount of liquid in the system is irrelevant, as long as liquid is present. If more gas is added, the pressure rises microscopically, causing more gas to condense, which lowers the pressure, and the system equalizes at the same pressure as before.
As long as there is one drop of liquid in the system the pressure will remain constant (assuming constant temperature). That's why I say nearly all the refrigerant will have to escape to activate the low pressure switch. A system that is normally charged with 2 lbs of refrigerant (typical for cars?) will still have liquid present with only a few ounces of refrigerant in the system.
If you look at your refrigerant gauges you will see a temperature scale around the dial, with a different temperature for each refrigerant. The pressure in the system will exactly match the temperature of the system, which if it's had time to stabilize at ambient, means the gauge will indicate ambient temperature as long as there is any liquid in the system.
Yes, pressure will rise as you fill a system, but there will be a time when pressure stops rising even though you add more refrigerant. This is why refrigeration systems are charged by the weight of refrigerant (even though it's much harder to measure) and not the pressure.
That's also why it's difficult to fill a system without running it. Once the liquid in the system reaches ambient temperature (same temp as the bottle) you can't put any more refrigerant in, because the pressures are the same. So you either have to dump a bunch of liquid in quick before it has a chance to heat up, or you have to run the system and add additional gas into the low side.
Think about this - if you can tell the state of charge by measuring pressure (like the pressure switch needs to do), you could simply connect your gauges to a static system, take a reading, and announce "it's 8 ounces low". But you can't.
.
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