AC problem

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Runaround

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I have a 2007 Ram. The AC isn't cooling as it should be. It gets cool but not cold. I noticed the high pressure line is icing up from the firewall to about half way forward while the truck is running with the AC on. I have pressure readings of 70-76 on the low side and 80-95 on the high side. What might my problem be?
 

crash68

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I have pressure readings of 70-76 on the low side and 80-95 on the high side. What might my problem be?
There is something wrong with the low side readings, 70-76 psi would put you upwards of 100°, unless those readings are in °F but then that would be low pressure on the High side and high pressure on the low side (possible compressor issue)
The icing is usually an indication of being low on refrigeration. Time to leak check and fix, then evacuate and weigh in the charge.
 
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Runaround

Runaround

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I don't understand what you mean 70-76 psi would put me upwards of 100 degrees, unless those readings are in degrees Fahrenheit.
These readings were taken at about 79degrees outside temperature (F).
 

crash68

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I don't understand what you mean 70-76 psi would put me upwards of 100 degrees, unless those readings are in degrees Fahrenheit.
All refrigerant have a temperature pressure correlation,(I just realized my P/T chart app is screwing up too) At a given pressure the refrigerant will be a certain temperature (or vice-versa). You didn't specify if the 70-76/80-95 was psi or the temperature converted from pressure, so I tried "filling in the blanks". I've done refrigeration for many years, I use temperature converted from pressure all the time.
Given the outside temperature was 79°F, the high side is definitely low but with the low side pressures being on the high side, you'll need to have the correct refrigerant charge in there to determine if there a problem with the compressor.
 
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Are you saying my charge might be a little bit low? What about the high pressure line icing over part way? What are your thoughts on this? As I said it is cooling some.
 

crash68

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Are you saying my charge might be a little bit low? What about the high pressure line icing over part way? What are your thoughts on this? As I said it is cooling some.
If this icing happes after a fitting/nut in the line going into the firewall, the office tube is in there and when the charge is low that line will usually ice up.
The low side pressures of 70-76 doesn't fit with just being low on refrigerant. It's possibly a bad reading as the low side is usually lower than 55 and will be even less if the charge is low.
 
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If this icing happes after a fitting/nut in the line going into the firewall, the office tube is in there and when the charge is low that line will usually ice up.
The low side pressures of 70-76 doesn't fit with just being low on refrigerant. It's possibly a bad reading as the low side is usually lower than 55 and will be even less if the charge is low.
I took another reading today, still about 80 degree outside temperature the high showed 125 psi and the low kept rising until I got a reading of around 95 after about 20 minutes when I shut it off. The line that freezes has some sort of clamp or connection right at the firewall and it ices about half way to the front where it is just cool and sweaty from there on forward
 

crash68

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The line that freezes has some sort of clamp or connection right at the firewall and it ices about half way to the front where it is just cool and sweaty from there on forward
The sweating should stop somewhere before the condenser.
I would leak check the system before recharging.
 
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I went ahead and put 12 oz. Of refrigerant to it and that got the pressure on the low up to 34 and the high to 160. It feels much better inside now and the icing has turned to just sweat now. If it leaks I will leak check then, since it might have taken 12 years to leak out this time, since I don't know the history of any AC work and I will have only lost out on less than $6.00. I did borrow a different set of gauges today from O'REILLY Auto parts.
Thanks for all of of the input.
 
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