Chevy Impala SS Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Hi there,

I drive a 95 Buick Roadmaster Wagon (quite rare in the Netherlands). Most of the time the Roadmaster drives great, but lately I'm having some problems with the interior heater.

The cabin is getting quite hot recently (despite the fact it's winter...). The heater seems to be stuck on a setting that blows hot air into the cabin. I assume the blend door (or heater valave) is stuck or the actuator (or rod?) is malfunctioning. Maybe it's a vacuum problem.

A/C in itself should be okay. Whenever I put the HVAC on 60 F, the interior air cools down just a bit (luke warm in stead of hot), but there is mainly hot air coming out of the vent openings.

I figured the heater valve keeps letting in hot air and doesn't allow outside air (or A/C air) to be mixed with it.

The problem is that I don't know where the valve is located. I guessed it would be somewhere behind teh glove box, but I have had no success in locating it until now.

Could someone point me in the right direction? Hope to get things fixed before the summer sets in.:)

I took some pictures, hoping that will help.

Thanks!
 

Attachments

·
Registered
Joined
·
10,905 Posts
The vacuum motors and linkage are located on the front of the air handler box. It could also be the selection valve, or a pinched vacuum line. Worst case scenario is the control unit is not functioning correctly. The vacuum motors and linkage are the same on all electronic climate control systems. The control head is unique to the 94-96 RM.

There is a flap valve that covers the heater core when lower temps are called for. I would look at that vacuum circuit first.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #3
Hi Fred,

I've found the vacuum lines (second picture), but don't know which one controls the blend door.

Where would the selection valve be located?

I guess the flap valve is the one in my first picture. I can press that one manually but it looks like that makes the system switch to recirculate cabin air.

Do you know how far the wite plastic driveshaft actuator in photo 3 is supposed to turn? I can see a plastic wheel turn just a bit when I switch from 65 to 60 F: it turns from the 12 o'clock position to the 11 o'clock position. Doesn't go beyond twelve though, not even when I turn up the temperature.

I do think it's a vacuum or "getting stuck" problem, because I got the system working again (although only for a short period of time - a couple of days ago when I was haphazardly pulling and pinching lines and cables. I knew I got things working again because the aircon was nice and cold on 60F. I'm not sure but I think I saw this white driveshaft turn further than it does right now. Can't reproduce it though.
 

·
Registered
Joined
·
2,058 Posts

·
Registered
Joined
·
10,905 Posts
Here are the pics from my FSM. The vacuum line routing should be the same.
 

Attachments

·
Registered
Joined
·
11 Posts
Discussion Starter #6
Which one controls the hot-cold air mixture? Fig. 4 no. 9 air inlet valve (+ orange hose) or the temperature air valve actuator?

I assume the temperature air valve actuator is electrically operated and that your 3rd picture is the same actuator as the one in my 3rd picture (the back screw is going to be a pain to get out...)
 

·
Registered
Joined
·
10,905 Posts
According to the legend in the first pic, the gray hose goes to the heater shutoff valve (B).
 

·
Registered
Joined
·
11 Posts
Discussion Starter #8
I thought the heater shut off was the one for turning everything off (by pressing off on the control panel).

I'll have a look at it again later on, when it's no longer freezing outside :)
 

·
Registered
Joined
·
11 Posts
Discussion Starter #9
Found the problem: the actuator controlling the mixture of hot and cold air didn't shut off the flow of hot air. Removed the actuator, opened it and removed the plastic gears. Put them back in after giving the big one a twist to change the range. Worked like a charm, at least for the time being.
 
1 - 9 of 9 Posts
Top