Diagram of heater hoses for a 1999 bontiac bonneville

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.

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HI,HERE'S A LINK TO YOUR HEATER HOSES. Hose Heater 1999 Chevrolet Venture FWD 6 Cylinders 3 4L SFI AutoZone com

On this website you find fuse box diagram and description for Pontiac Boneville (1999)

Pontiac Boneville 1997 1999 fuse box diagram Auto Genius

There are 2 rubber hoses that get hot when the engine is running. They come from the engine and connect to the heater core at the firewall The hose is about 3/4 inch in diameter and is hot to the touch after the engine is up to operating temperature.

HEATER CORE REMOVAL AND INSTALLATION 1997–01 Models BONNEVILLE AND LESABRE

1. Disconnect the negative battery cable.
2. Drain the cooling system into a clean container for reuse.
3. Remove or disconnect the following:
   • Heater hoses from the heater core
   • Right sound insulator
   • All necessary electrical connectors and remove the instrument panel compartment
   • Temperature valve actuator
   • Electrical connector and remove the HVAC programmer
   • Heater core cover-to-heater assembly screws and the cover
   • Heater core-to-heater assembly screws and the heater core Fig. 1: View of the heater hoses and clamp positions — 1997–01 Bonneville and LeSabre
     Fig. 2: View of the heater core cover — 1997–01 Bonneville and LeSabre
     
   To install:
   
4. Install or connect the following:
   • Heater core and the heater core-to-heater assembly screws, then, tighten the screws to 12 inch lbs. (1.4 Nm)
   • Heater core cover and the cover-to-heater assembly screws, then, tighten the screws to 12 inch lbs. (1.4 Nm)
   • HVAC programmer and connect the electrical connector
   • Temperature valve actuator
   • Instrument panel compartment and connect any necessary electrical connectors
   • Right sound insulator
   • Heater hoses to the heater core
5. Refill the cooling system.
6. Connect the negative battery cable.
7. Operate the engine to normal operating temperatures; then, check the climate control operation and check for leaks.

1999 Pontiac Bonneville V-6 3.8L



From Gates.com / Part Locator

I hope help you with this. Good luck.

This is the one for the supercharger.

Grab yourself a cable type hose clamp tool.. a long pair of hose removal pliers. drain the radiator and remove the hose clamps and hosed from the passenger side firewall ( hidden behind the A/c acumulator ).
from the passenger side remove the end cap from the heater box under the dash. take it out and put it back together in the reverse order.