AC low side higher pressure than high side
Thread Starter
Intermediate
Joined: May 2018
Posts: 40
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From: Dallas, Texas
AC low side higher pressure than high side
My AC hasn’t blown cold air in months. I haven’t tried to fix it because I’ve been dealing with other things. Today I hooked up gauges and saw that it was at 85 on the low side and 100 on the high side. I know the ranges should be 35–55 on the low and 150–270 on the high. This was at 84F ambient, car on with the AC running, fans on. The compressor is engaged and spinning when the AC is on.
I wanted to see what y’all think before I add any more Freon, since I don’t want to overfill it and damage anything. I saw some posts on different forums about possible leaks, but I would think if that were the case, there wouldn’t be any Freon left. I also read something about an obstruction in the system, which makes sense, I guess—maybe? If that’s the case, where should I look first? I saw another post mentioning the expansion valve. What do y’all think I should check first?
I wanted to see what y’all think before I add any more Freon, since I don’t want to overfill it and damage anything. I saw some posts on different forums about possible leaks, but I would think if that were the case, there wouldn’t be any Freon left. I also read something about an obstruction in the system, which makes sense, I guess—maybe? If that’s the case, where should I look first? I saw another post mentioning the expansion valve. What do y’all think I should check first?
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From: Cape Coral, Florida
It’s an “orifice tube”…the C6 uses an expansion valve (TXV).
Thread Starter
Intermediate
Joined: May 2018
Posts: 40
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From: Dallas, Texas
Ok, thank you! I'm going to buy a new orifice tube and install it. I saw a video (
) where someone added PAG150 oil but didn’t mention how much. Should I be doing that with this job? I also watched another video about a different vehicle where they said not to add oil because the compressor already comes with it and adding more would cause overfilling. I’m not changing the compressor or the condenser.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
NO, you don’t need to add PAG oil for just an orifice tube change…if it did hold oil then you need to worry about it…now are you having someone recover the refrigerant before changing it ??…you do know you have to pull the system into a vacuum before adding refrigerant ??…DIY’ers like yourself shouldn’t be doing AC work.
Thread Starter
Intermediate
Joined: May 2018
Posts: 40
Likes: 0
From: Dallas, Texas
NO, you don’t need to add PAG oil for just an orifice tube change…if it did hold oil then you need to worry about it…now are you having someone recover the refrigerant before changing it ??…you do know you have to pull the system into a vacuum before adding refrigerant ??…DIY’ers like yourself shouldn’t be doing AC work.
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My AC hasn’t blown cold air in months. I haven’t tried to fix it because I’ve been dealing with other things. Today I hooked up gauges and saw that it was at 85 on the low side and 100 on the high side. I know the ranges should be 35–55 on the low and 150–270 on the high. This was at 84F ambient, car on with the AC running, fans on. The compressor is engaged and spinning when the AC is on.
I wanted to see what y’all think before I add any more Freon, since I don’t want to overfill it and damage anything. I saw some posts on different forums about possible leaks, but I would think if that were the case, there wouldn’t be any Freon left. I also read something about an obstruction in the system, which makes sense, I guess—maybe? If that’s the case, where should I look first? I saw another post mentioning the expansion valve. What do y’all think I should check first?
I wanted to see what y’all think before I add any more Freon, since I don’t want to overfill it and damage anything. I saw some posts on different forums about possible leaks, but I would think if that were the case, there wouldn’t be any Freon left. I also read something about an obstruction in the system, which makes sense, I guess—maybe? If that’s the case, where should I look first? I saw another post mentioning the expansion valve. What do y’all think I should check first?
A plugged orifice tube should cause very high pressure on the high side until it reached the high pressure cut out setting which would shut off the compressor. The system would be cycling on and off based on the high side pressure.
A missing orifice tube, or one that was not sealed on the liquid side of the high pressure line, would not be able to build high pressure and liquid refrigerant flowing into the compressor from the suction side would probably have a high suction pressure. So if someone messed with the system, maybe cut the oring on the orifice tube, forgot the oring, or maybe put it in backwards, I think that could result in low high side and high low side pressures.