Automotive Air Conditioning Information Forum (Archives)

HarvO on Fri July 16, 2010 10:50 AM

Year: 1998
Make: chevrolet
Model: suburban
Engine Size: 5.7 litr
Refrigerant Type: R134a
Ambient Temp: 95F
Pressure Low: 35psi
Pressure High: 260psi
Country of Origin: United States

On the dual air system for 98 suburban, does the orfice tube only reduce pressure for the front evaporator? I know the rear evaporator uses an expansion valve. Is the orfice tube located at the condensor fittings or at another fitting?

HVargas on Fri July 16, 2010 11:13 AM

On a rear air system, the orifice tube is located in the front evaporator. In a front air system, it is located in the condenser. The high pressure line will T off to the rear expansion valve and that is what regulates the rear evaporator. That is why when a system goes low, you will usually notice the rear air blowing warm before the front.

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HarvO on Fri July 16, 2010 11:55 PM

Thanks for the help. The rear air is working well 38-40F. The front air is 65F. Could this be a clogged orfice tube? The fan clutch is fine and the condenser fins are clean.