Can't get heat out of "floor" position


Former LOD President
My navigator has been acting a little goofy lately. There are a couple of problems that may be interrelated.

First, the heat won't blow out of the "floor" position. It will blow out of defrost, vents, or defrost and floor, but as soon as you switch it to floor, it goes out of the defrost only.

Second, it takes a second longer to crank in the morning. Instead of firing right up, it cranks for 3 seconds or so before starting. My 1st guess on this was FPR but it might be related to the HVAC issue through the vacuum system.

I checked for vacuum leaks (didn't find any, that doesn't mean there aren't any) and replaced the actuator in the HVAC system that sends air to the floor and it didn't fix the issue.

Any other ideas?


El Presidente
Staff member
From the '99 manual...

When PANEL/FLOOR is selected:

The panel/defrost door is at full vacuum, closing off airflow to the windshield defroster hose nozzle.

The floor/panel door is in the partial vacuum position, allowing airflow to both the heater outlet floor duct and the instrument panel A/C registers.

When FLOOR is selected:

The floor/panel door is in the full vacuum position, directing all airflow to the heater outlet floor duct.

The panel/defrost door is in the no vacuum position, blocking air circulation to the instrument panel A/C registers.


Former LOD President
Do you have that manual electronically? I'd love a copy, if so. If not, can you pull a little more troubleshooting info out of there for me?

Alldata sucks. Totally ignorant organization. They redid the site a year or so ago and made it nearly impossible to access any information that's of any value. I couldn't find ANY troubleshooting info on the HVAC system.

Is there a description of operation or a vacuum diagram in your manual? That would really help me out.

I did some further diagnosis yesterday. I have a vacuum pump with a gauge. It appears that there is a vacuum leak inside the vehicle somewhere. I used my vacuum pump to try to operate the HVAC doors with the vehicle off. It functions - somewhat. The vacuum bleeds down rapidly in all settings, although some are worse than others. I didn't spend too much time on it, because I also had to do a thermostat and oil filter adapater gasket on the mark 8. Ugh.


Former LOD President
Well JP, the diagram and pages you sent me were of great help. I managed to diagnose it as the EATC main control unit. When I unplug that unit and bridge the vacuum ports appropriately, I get floor. I took the unit apart and found that it has 4 solenoids. There are 5 lines, one for vacuum input, then the other 4 are controlled by the solenoids. The floor vent uses 2 lines - one for half way (floor / defrost, panel / defrost) and the other one (actually both at once) for all the way. The "all the way" one is only used for the floor position. That's the solenoid that's bad.

The junkyard has one, i'll pick it up on Monday. Should be fixed in time for the drive to Florida on Friday.