? low pressure ac pirt on 00 gmc yukon?

[Topher265]

I was going to say, the low press of 55 wasn't low enough. It should average around 35 on the low side (the green area of your gauge), lowest of 30-33 when getting pulled down while the compressor is running, then it raises back up as the temps equalize between high and low side, plus absorbing heat from the passenger cabin.

 

[Soundguy]

my gauge didn't have numbers.. just a jinky white ( low ) green ( good? ) and red ( too high ) .. the 55 psi # i saw was in a lil booklet that compaired outside temps to psi. and yeah.. I noticed when compressor ran,t he needle sucked down just a hair.

I'm at the low end of green now. should i add another few seconds of charge to get it more middle of the green area?

thanks ( i'm no ac guy.. )

 

[Topher265]

my gauge didn't have numbers.. just a jinky white ( low ) green ( good? ) and red ( too high ) .. the 55 psi # i saw was in a lil booklet that compaired outside temps to psi. and yeah.. I noticed when compressor ran,t he needle sucked down just a hair.

I'm at the low end of green now. should i add another few seconds of charge to get it more middle of the green area?

thanks ( i'm no ac guy.. )

I see what you're saying. The truth is this is only 1/2 the story though, as you only have that one gauge. What the high-side is doing is also important. But in your case at least it was simply low refrigerant charge.

For 55psi to be normal (with 134a) you're talking about ambient temps of 95-105F.

Your truck has what is called a CCOT system - Cycling Clutch Orifice Tube. Ambient temp & humidity do influence what to expect out of any AC system. The lower the average low side, the better...but only to a point. You don't want the evaporator (radiator inside the passenger compartment that is absorbing heat) to freeze because the low side is too low. Ideal is usually around 35-45psi which is ambient of 70-90F and "normal" humidity (most situations). Also, it's important to look at the gauge with all the windows up, max cold temp selected and recirculation on while running around 1900-2000rpms. Let it run for a few mins to see what the pressures really look like.

I'd add a bit more refrigerant to be in the middle green to upper-middle green area.

 

[Soundguy]

yes exactly.. the booklet said outside temps at 95.. etc. for the 55 psi reading.

When i originally looked the yukon over ( here in florida ).. the outside temps were that high.. but i wanted to ask questions first.. so after a few hours sun went down and i posted and got help here, the pressures went down.

and yup. booklet said windows up, max ac, and to have let it run 10m or so

( which i did ).

wallymart has them small booster cans i'll grab another on the way home.

was glad to see it was not totally out. truck is running good.. just getting old. I want to get another year out of it before replacing if i can.

And i agree.. i don't have the 2 gauge set.. only the one. Not ideal.. but.. I had picked it up a while back to just test with.. had never even removed the lil tab from the can so it could be screwed in ..e tc.

thanks for the help

I know hwat an orifice tube is.. just not a clue about the ccot setup.

thanks

I see what you're saying. The truth is this is only 1/2 the story though, as you only have that one gauge. What the high-side is doing is also important. But in your case at least it was simply low refrigerant charge.

For 55psi to be normal (with 134a) you're talking about ambient temps of 95-105F.

Your truck has what is called a CCOT system - Cycling Clutch Orifice Tube. Ambient temp & humidity do influence what to expect out of any AC system. The lower the average low side, the better...but only to a point. You don't want the evaporator (radiator inside the passenger compartment that is absorbing heat) to freeze because the low side is too low. Ideal is usually around 35-45psi which is ambient of 70-90F and "normal" humidity (most situations). Also, it's important to look at the gauge with all the windows up, max cold temp selected and recirculation on while running around 1900-2000rpms. Let it run for a few mins to see what the pressures really look like.

I'd add a bit more refrigerant to be in the middle green to upper-middle green area.

 

[Soundguy]

yes exactly.. the booklet said outside temps at 95.. etc. for the 55 psi reading.

When i originally looked the yukon over ( here in florida ).. the outside temps were that high.. but i wanted to ask questions first.. so after a few hours sun went down and i posted and got help here, the pressures went down.

and yup. booklet said windows up, max ac, and to have let it run 10m or so

( which i did ).

wallymart has them small booster cans i'll grab another on the way home.

was glad to see it was not totally out. truck is running good.. just getting old. I want to get another year out of it before replacing if i can.

And i agree.. i don't have the 2 gauge set.. only the one. Not ideal.. but.. I had picked it up a while back to just test with.. had never even removed the lil tab from the can so it could be screwed in ..e tc.

thanks for the help

I know hwat an orifice tube is.. just not a clue about the ccot setup.

thanks

I see what you're saying. The truth is this is only 1/2 the story though, as you only have that one gauge. What the high-side is doing is also important. But in your case at least it was simply low refrigerant charge.

For 55psi to be normal (with 134a) you're talking about ambient temps of 95-105F.

Your truck has what is called a CCOT system - Cycling Clutch Orifice Tube. Ambient temp & humidity do influence what to expect out of any AC system. The lower the average low side, the better...but only to a point. You don't want the evaporator (radiator inside the passenger compartment that is absorbing heat) to freeze because the low side is too low. Ideal is usually around 35-45psi which is ambient of 70-90F and "normal" humidity (most situations). Also, it's important to look at the gauge with all the windows up, max cold temp selected and recirculation on while running around 1900-2000rpms. Let it run for a few mins to see what the pressures really look like.

I'd add a bit more refrigerant to be in the middle green to upper-middle green area.

 

[Topher265]

yes exactly.. the booklet said outside temps at 95.. etc. for the 55 psi reading.

When i originally looked the yukon over ( here in florida ).. the outside temps were that high.. but i wanted to ask questions first.. so after a few hours sun went down and i posted and got help here, the pressures went down.

and yup. booklet said windows up, max ac, and to have let it run 10m or so

( which i did ).

wallymart has them small booster cans i'll grab another on the way home.

was glad to see it was not totally out. truck is running good.. just getting old. I want to get another year out of it before replacing if i can.

And i agree.. i don't have the 2 gauge set.. only the one. Not ideal.. but.. I had picked it up a while back to just test with.. had never even removed the lil tab from the can so it could be screwed in ..e tc.

thanks for the help

I know hwat an orifice tube is.. just not a clue about the ccot setup.

thanks

Perfect. Then yeah, for your plan I would just add some more refrigerant until it's cooling the way you want. It should last a year unless you have a more significant leak.