Rear Heater

After changing out the IMG last month now I am on to knocking out some of the more minor issues with my new to me 98 Venture.

I am not getting warm air flow from the rear heater. I have the factory manuals but although their is 3 volumes they don't do a good job of addressing the rear system.

I have all the controls (front and rear) turned to full heat yet I only get cool air flow from the overhead rear vents 0 same vents as A/C. The fan (blower) is working fine. Here is were I need some help:

1. Do these vans use the same overhead air vents for the heat and A/C? ( I know on my old Chrysler the heated air came out at the floor level but I don't see any vents at this level except for one at the very back on the drivers side and I assume that vent is for the return air)

2. If the air flow should be coming from somewhere besides the overhead vents then I will suspect the actuator isn't getting vaccum and will open up the side panel to test/check it out.

3. Should the rear heater pipes under the van be getting warm even when the rear heater isn't working? If they are cold to touch maybe I have an air pocket that still hasn't worked out after changing the IMG ?

The top roof vents throw out heat and A/C to the rear. (provided the rear controls are set correctly)

Yes, the cold air return is next to the floor on the drivers side rear panel.

I would have to guess that those rear heater hoses would be at least warm/hot along with the main heater hoses. I've never checked my 2000 Silo.

[QUOTE=roadrunner2]The top roof vents throw out heat and A/C to the rear. (provided the rear controls are set correctly)

Behind that large vent in the left rear trim panel is the rear HVAC blower and heater core , not a cold air return.

I would have to guess that those rear heater hoses would be at least warm/hot along with the main heater hoses. I've never checked my 2000 Silo.[/QUOTE

The Haynes repair manual #38036 shows the system quite clearly. (pages 3-8, 3-9, 3-10)

ARRGH! this edit procedure doesn't work for me.

Disregard the second sentence in my first post.

[QUOTE=roadrunner2]The top roof vents throw out heat and A/C to the rear. (provided the rear controls are set correctly)

Behind that large vent in the left rear trim panel is the rear HVAC blower and heater core , not a cold air return.

I would have to guess that those rear heater hoses would be at least warm/hot along with the main heater hoses. I've never checked my 2000 Silo.[/QUOTE

The Haynes repair manual #38036 shows the system quite clearly. (pages 3-8, 3-9, 3-10)

There should be a heater control valve that allows coolant to flow to the rear heater core when the control knob for the rear is turned on. This valve will also shut off coolant flow to the heater core when the A/C is running so they aren't competing with each other. You probably have a bad vacuum line to the control valve or the vacuum switch isn't working.