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“Normal” pressures, low subcool

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19K views 165 replies 15 participants last post by  Olivero  
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#1 ·
A lot of times when I am checking TXV equipped units I’ll have normal pressures with a very low subcool. For example. 75 indoor. 20 delta t. 85 outdoor. Pressures around 320/130 psi. Subcooling 2. What would cause this? Now I know low subcool could be indicative of a low charge but with these pressures and good delta t I don’t think this is the case. I guess the superheat would come into play here as well to determine why the subcool is so low?
 
G
#75 ·
Im just doing PMs. From 9 to 5, 2 hours per house. I don’t take every reading in the world, because i wasn’t trained to do so. I make sure they re pressures are proper and everything is clean and drain lines clear etc. the only way I would start to take wet bulb or static pressure was if the customer complained about humidity or airflow problems
 
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#114 ·
TechmanTerry said:
What is that formula for figuring out Target Super Heat ? WB x 3 - 80 - ODAT / 2.
Click to expand...
Olivero said:
Suction pressure will change slightly depending on exterior conditions or wherever your condenser is but the simple fact is that the system is designed to work within a wide range of ambient temperatures. It's not like your A/C won't work in the winter just because it's cold. There's components and features added to make up for such things.

IF your suction pressure is way too low, I don't care what temp it is outside, there's a problem that needs to be fixed.
Click to expand...
There’s a reason why most user manuals tell you not to operate your AC when it’s below 55 outside. I’ve had to do plenty of checks were it was only 40 outside. I’ve seen suction as low as 30 psi and was fine that summer without putting refrigerant in
 
#116 ·
Ghyde6005 said:
There’s a reason why most user manuals tell you not to operate your AC when it’s below 55 outside. I’ve had to do plenty of checks were it was only 40 outside. I’ve seen suction as low as 30 psi and was fine that summer without putting refrigerant in
Click to expand...
Yes there is a reason...……………………..

Why is that?

We run A/C & Refrigeration systems in all temperature and conditions!
 
A
#91 ·
TT,

He don’t know what a properly operating unit is. He has preconceived notions that all his customers are either too cheap or it is not worth it to fix the issues so he don’t check for any issues.

If he knew what a properly operating unit was, he would know how off his mis conceptions are.

He only does PMs as he could not fix a unit if he wanted to. His bosses have preconceived notions that he is a lazy hack...

Wow.
 
T
#102 ·
OP, you say an awful lot of "seen it many times" & " got 100's just like that" & "they can't ALL be wrong". How about some book knowledge mixed up in there somewhere.? Got milk? Got info?Then w/ some solid references we might start to listen to you and you might even help educate us. But Dude, not the "I SAW IT. I SWEAR!" way. Not with "this crowd"! We need proof, not jaw flapping.
 
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#147 ·
But nah I already do more then most. My coworkers won’t even pull blowers. I won’t do this for much longer. I do want to take more readings but when you got customers cussing you out for a small hole for a thermometer m their duct work toy become hesitant to drill holes. And unless they want to revamp their whole ac system I don’t see the need to take all those readings unless I need to do some investigating
 
O
#151 ·
There's a difference between

1. Recognizing that a system is not perfect and finding out why, and knowing how to solve it.
2. The idea that the customer doesn't care, so you see it's not perfect but don't find out why because the customer won't care either way.

I think that's what most people here have an issue with, you are coming off as the 2nd type.

You originally said you didn't want to dive into these things and spend all this time because the customer didn't care, yet adding 1/2 lb of refrigerant to figure out if the TXV is working properly is not incorrect, it's troubleshooting. But if you are adding 1/2 lb of refrigerant, most of the numbers requested should be gathered to get a real idea of what's changing when that refrigerant is added.

I would expect at least, outside temp, inside temp, high side pressure, SC, low side pressure, SH and the condition of both coils, blower and a good idea of airflow, EVEN if it's just feeling the vent to see if there's air coming out, at least SOME verification of airflow.
 
S
#154 ·
On site per usual, this is one funny Thread, the guru PSE is laughing hard at how much he scorned most of you bahahahhahahaah

OP add the juice til big pipe icey cold, like techman terry does.

Don’t let them force you to worship them, they had more callbacks in the past month than I had since January.
 
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