'98 Chevy Venture Air compressor quit working

I couldn't find a heater hose diagram specific to the 1999 Chevrolet Venture with rear heat and air, but I can give you the general location of the heater hoses and how to identify which ones go to the rear heat. The heater hoses on a 1999 Chevy Venture are located on the passenger side of the engine compartment. There are two heater hoses, one that is hot and one that is cold. The hot heater hose will be connected to the heater core, which is located under the dashboard. The cold heater hose will be connected to the engine. To identify which heater hose goes to the rear heat, you can look for the hose that is connected to the heater core outlet that is labeled "Rear Heat." The other heater hose will be connected to the heater core outlet that is labeled "Heating Core Inlet." Once you have identified the heater hoses that go to the rear heat, you can reconnect them to the heater core. Be sure to use new clamps when you reconnect the hoses. Here are the steps on how to replace the heater hoses on a 1999 Chevy Venture with rear heat and air: Disconnect the negative battery cable. Drain the coolant from the radiator. Remove the heater hoses from the engine and heater core. Install the new heater hoses. Fill the cooling system with coolant. Reconnect the battery cable. Start the engine and check for leaks.

On the high pressure side of the system on the line that goes into the evap just at the engine compartment firewall. Sometimes it is wrapped with an insulation and is hard to find.

Is the ac compressor clutch and pulley turning ?

The air compressor on mine was under the hood on the driver's side, in front of the master cylinder

The load leveler sensor operates the compressor. It most likely is malfunctioning. It is located on the rear drivers side lower control arm.

The pcm is located inside the airbox in the drivers side front corner of the engine compartment. You need to remove the air filter, and it is an aluminum box with fins at the bottom of the box.

The hose goes on the compressor by the left rear shock

I'm afraid I must recommend some professional help with this one. Or maybe a mechanic friend.
There's so many things..... For example the 134a (freon) may have leaked causing the Low Pressure Cut Out Switch, (in the hose under the hood) to keep the compressor off so as to not burn it up.
Could be a fuse or relay. Could be the switch controll on the dash... See what I mean?
Sorry but in my opinion you'll have to bite the bullet and pay the piper. Cheaper in the long run, though. You can replace many things before you luck onto the problem part.

On your 2003 yukon denali, the air ride compressor is located on the driver side rear frame rail on the outboard side, near the fuel filler neck and behind the left rear wheel. Hope this helps!

The A.I.R pump is located on the driver's side of the vehicle, just in front of the front tire. If you remove the tire & look at the inner fender well, you'll see that it's designed with a "trap door". Remove the screws that hold the door closed, then fold the door back to reveal the pump. What usually happens is the pump sucks in the sponge filter on the intake side & it lodges in the impeller blade...this causes the fuse to blow & eventually a code will set & the Service Engine Light will come on. The fuse is located under the hood in the black fuse box on the passenger side...the box should be clearly visible & easily accessable. Look for a 30A fuse, probably in location # 39.