Trouble Shooting Air Conditioner (a/c)

[BigSilver]

2003 Chevy Suburban, 2500, 6L, with rear A/C.

Situation: No cool air.

 

Checked on low side, refrigerant level to be at aproaximatly 50psi with ambient temperature at 39C.

 

Per Tech Tool (TT), A/C clutch engages from dash switch, and manually through TT.

 

Tube connected to A/C accumelator was cool to touch but not cold enough to sweat. A/C output air was ambient.

 

Through the TT, A/C pressure sensor indicated 1.80volts and 162psi, when A/C unit was engaged.

 

Does this senario look like a compromised A/C pump?

[dewfpo]

2003 Chevy Suburban, 2500, 6L, with rear A/C.

Situation: No cool air.

 

Checked on low side, refrigerant level to be at aproaximatly 50psi with ambient temperature at 39C.

 

Per Tech Tool (TT), A/C clutch engages from dash switch, and manually through TT.

 

Tube connected to A/C accumelator was cool to touch but not cold enough to sweat. A/C output air was ambient.

 

Through the TT, A/C pressure sensor indicated 1.80volts and 162psi, when A/C unit was engaged.

 

Does this senario look like a compromised A/C pump?

 

When you measured the 50 psi on the low side, was the engine running? A/C compressor on or cycling at the time?

 

When running/cycling, the low side pressure should run between 25-45 psi if charged properly and everything in working order.

 

DEWFPO

[BigSilver]

2003 Chevy Suburban, 2500, 6L, with rear A/C.

Situation: No cool air.

 

Checked on low side, refrigerant level to be at aproaximatly 50psi with ambient temperature at 39C.

 

Per Tech Tool (TT), A/C clutch engages from dash switch, and manually through TT.

 

Tube connected to A/C accumelator was cool to touch but not cold enough to sweat. A/C output air was ambient.

 

Through the TT, A/C pressure sensor indicated 1.80volts and 162psi, when A/C unit was engaged.

 

Does this senario look like a compromised A/C pump?

 

When you measured the 50 psi on the low side, was the engine running? A/C compressor on or cycling at the time?

 

When running/cycling, the low side pressure should run between 25-45 psi if charged properly and everything in working order.

 

DEWFPO

 

 

Re-checked the A/C, with system running, and sure enough the refrigerant was too low. Thanks for the feedback DEWFPO.

 

At the same time I found the oil (PAG) was too low. Do I need to vacuum the system to top up the oil?

[Doug_Scott]

Re-checked the A/C, with system running, and sure enough the refrigerant was too low. Thanks for the feedback DEWFPO.

 

At the same time I found the oil (PAG) was too low. Do I need to vacuum the system to top up the oil?

 

 

Technically vacuuming will not remove the oil, it is suspended in the refrigerant mostly, and some comes out with the draining of the system. Vacuuming removes any moisture by making it boil at room temp due to the vacuum. I gave up the mechanics trade before the switch to R134, my training/experience is in R12. How did you check oil level, and if it is down, you need to drain the system, and depending on the machine you are using (you are recovering the refrigerant aren't you?), you either add the oil, then vacuum, or vacuum first then add oil. If you are doing it backyard style, add oil first, then vacuum, then fill with refrigerant. Keep in mind to vacuum correctly, it should be sitting at close to -30 for at least half an hour.