I have a 1998 GMC Suburban 1500 it is equipped with front and rear AC/Heat, A New compressor, Orifice, and condenser has been installed, system has been vacuumed and proper amount refrigerant installed. If the outside temps are below90 it cools to 57deg. But when the outside temp gets into the 90's (In Kentucky) it only cools to about 66 deg. Any suggestions or ideas on why it will not cool down to the 40's??
Thanks

 

Yes...There OK

 

Moving to the Suburban section of the Forum where you will get more views.

 

DYI job or by a paid professional?

 

First of all, cooling to 57F sucks big time. Here in Arizona desert, our 1988 and 1994 Suburbans and our 2005 and 2011 Yukons all had dual air, and all did way better than that, even with 115F outside temperatures.

First of all, I hope you didn't add any sealer or refrigerant containing sealer, that could ruin things permanently.

Questions:
How much R134a did you add, like dual AC systems require different amount than front-only systems.
Was the refrigerant added from cans?
Were the hoses vented of air?
Was the system fully evacuated, and vacuum verified after 15 minutes?
Did you add any refrigeration oil when you did the repair?
What are your low pressures and high pressures at about 2000 rpm?
Did you test or replace your fan clutch? Significantly higher vent temperatures can cause poorer temperatures at low speeds or idling.
Is the complete fan shroud in place?
Did you add any UV dye? Check for leaks with UV light and goggles?

 

Dirty filters can hinder air flow more than temperatures.