I have 1998 chev suburban with rear air do they use two orifice tubes
Most orifice tubes are placed in the high pressure line to the evaporator at the fire wall connection. You will have to empty the freon from the system to replace the orifice tube which is not very expensive (the tube, that is).
On some suburbans its at the connection behind passenger turn signal.
Located in front of the radiator on the passenger side in the condensor line.
BR
There is no expansion valve. There is an orifice tue. It is located in the inlet tube of the evaporator core.
it is located in the bottom line under the accumulator
Many GM vehicles put the AC orifice tube right after the condenser coil. It would typically be near the bottom, almost connected to the condenser. My '99 Suburban AC orifice is located in the line that runs across the passenger side inner-fender. There is a union very close to the innermost edge of the battery tray. Break that union (after relieving pressure) and you will find it there.
Orifice tube on f150 with 4.2
It does not have an orifice tube.
It uses an expansion valve, not an orifice tube.
The orifice tube is located between the engine and the fire wall. The windshield wiper cowling has to be removed to gain access to the orifice tube.
The 98 Blazer doesn't have a Thermal Expansion Valve... it has a fixed orifice tube.