1999 Suburban LT – AC Not Cold

[GaOkie]

Ok we have a 1999 Suburban LT (4x4) with 209,000 miles. Last summer the AC seemed to work ok (could have been colder) but toward the end of summer wasn’t blowing near as cold as it should have. Today (80 deg) started engine up added just a little 134a but neither the front nor the back is blowing cold at ALL. I don’t really know anything about the AC system but the AC clutch engages for 5-10 seconds then disengages for about the same amount of time then engages again. Seems to be short cycling to me. We’ve driven about 15 miles and nothing really changed. Any suggestions?
Thanks,

[temperingloser]

If compressor clutch comes on and goes off it must be low on refrigerant and you will need to add more but only add it when the compressor is running there must be a leak somewhere in your sytem

[GaOkie]

Installed the refrigerant with a gage attached and per the gage i'm within the recommended range. Based on that i should still add additional refrigerant? How much more?

Thanks

[j cAT]

Originally Posted by GaOkie

Installed the refrigerant with a gage attached and per the gage i'm within the recommended range. Based on that i should still add additional refrigerant? How much more?

Thanks

when you add refrigerent with these add kit guages you have no idea what is going on with the system and how much is in there.

best method is to buy a guage set. with the low and high pressures you can determine the correct charge.

with a temp of 80 degf all doors open and the fan on max with the engine at about 1500RPM. the low side should be 40-45 psi the high side should be about 300psi.

what is also needed is 2 oz of pag 150 refrigerent oil. this comes in a charge can of around 4-5oz total. this will add what was lost over the years and reduce compressor seal leaking of refrigerent.

PAG 150 OIL !