Heat thru vents

[Boone83K10]

My heat only blows through the floor or defrost. If I switch to vent it sounds like it is just circling inside the heater box. If I slide it over to cold, it blows hard out the vents. I checked all the actuators and vacuum lines plus the back of the control unit and everything is good.

Is this correct? Why cant I get hot air out of the vents.


EDIT: Heat will blow through vents barely if I put it on Bi Level but mainly coming out of the floor.

 

[Boone83K10]

anybody?

 

[350runner]

Did you check the vac bulb under the hood?.

 

[MadOgre]

Check behind the glove box there is an actuator rod with a little white plastic clip that is adjustable. sounds like maybe it broke.

 

[Boone83K10]

Did you check the vac bulb under the hood?.

vacuum bulb and line is good. vacuum line from engine is good.

Check behind the glove box there is an actuator rod with a little white plastic clip that is adjustable. sounds like maybe it broke.

I took the glove box out and took the vent routing plastic off. the door moves correctly, nothing is broken. it blows hard out the blend door hole when on heat and vent. but when I put the vent routing plastic back on.. nothing comes out the vents. yes they are connected at the back of the vents.... it's so weird!

 

[MadOgre]

vacuum bulb and line is good. vacuum line from engine is good.



I took the glove box out and took the vent routing plastic off. the door moves correctly, nothing is broken. it blows hard out the blend door hole when on heat and vent. but when I put the vent routing plastic back on.. nothing comes out the vents. yes they are connected at the back of the vents.... it's so weird!

You checked the ROD ? That moves the door ?

 

[Boone83K10]

Yes, rods and cables are good

 

[Boone83K10]

I was looking at the troubleshooting diagram on the sticky in this section... it says on heat mode that vacuum is only applied when on floor or defrost, no vacuum is applied when you select vent in heat mode....

is this my explanation?

 

[350runner]

Switch.

 

[Boone83K10]

Switch.

can't be, I checked vacuum at all lines when I switched it at control head. everything had vacuum when it should. Also when I have it on vent, as I slide the temperature knob over to cold from hot, it begins to blow hard out the vents.

 

[MadOgre]

Sounds like a mechanical door issue

 

[Boone83K10]

I was a-feared of that....this past January it was below ZERO 18 times and I about froze because I couldn't get hot air on me. Floor keeps the carpet warm and defrost keeps the glass warm and not me....

 

[chengny]

The cable operated temperature control is entirely independent of the vacuum operated air distribution system. There should be no change in air distribution - when the temperature setting is changed. So when you say:

"If I switch to vent it sounds like it is just circling inside the heater box. If I slide it over to cold, it blows hard out the vents"

That makes me think that there is some kind of interference between the temperature blend door (145) and the distribution valves. There are two directional doors that are linked together by an external rod (153). Only the inner valve (171) is operated directly by a diagram motor (53), the link transfers that motion to the outer valve (163).

If there is any place where the two systems (temp/distribution) could impact each other, it would most likely be in the area of the pivot pins for the blend door and outbd valve.

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I have an HVAC system installed in my truck that is currently fully operational but has no duct work or any of the adapters installed on the main air handler box. The dash board is stripped down to the steel frame. Before writing this post, I went out and observed - as best as I could - the motion of all the “valves” and dampers.

As stated above, moving the temperature slide full range - from hot to cold - had no impact of any of the distribution components. They did not change position and air flow out of the vents didn’t change – this was true no matter what the directional slide was set to.

The action of the parts you want to observe is directly behind the duct assembly - right over the hump (duct assembly item 189). Remove the single screw securing the floor register (outlet – 197) and the 3 screws holding 189 in place. The duct assembly can be pulled off the main body of the air handler and out of the transition piece (191) that heads over to the driver’s area.

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To describe the complete action of the dampers in detail would take more time than I have tonight. But if you go out and cycle through the various air flow options, it will quickly become apparent what is (or is supposed to be) happening.

 

[Boone83K10]

Ok. I did this already on Monday. I took off part 189. I could see the blend door and it moves freely. When vent is selected, and temp is on hot, it blows out the hole left by part 189. So that would mean it should continue to the vents. When I switch to cold, the door moves and shuts off the heater core side and blows out the hole left from part 189. When I put part 189 back on, it does not come out the vents none of them if it is on hot. It sounds like someone blowing thru a straw into a plastic cup. When I go to move to cold, it is hard to get the lever moving and then all the sudden a big rush of air comes out the vents and blows very hard. I put a new blower motor on back in Dec and that's when I noticed it wouldn't come out vents.

 

[chengny]

You shouldn't be able to ever see the "blend door" from the opening in the front. No matter what position valve 163 is in, it is always blocking the view of the blend door.

The blend door is unmistakable. It has a rubber sealing lip that runs along the top, front and bottom edges. If you can see the blend door through the front opening, it would mean that 163 is no longer in the correct position. And that is a bit of an issue.

Remove the external link (that connects the two valves) from the plastic clip at the RH end. It looks like it needs to be threaded in and out, but just lift up on it. It will snap right out of the gap in the plastic. Oh yeah - mark it so it can be snapped back in at he same spot.

With the actuating rod removed, twist the arm that drives the valve shaft. Stroke it from stop to stop. You might have to torque the spring loaded arm on the other end of the rod to get the LH valve out of the way. They are designed to work as a pair and if not timed correctly by the link, they will hit each other :

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Does the valve move smoothly and kind of "clank" at the end of the strokes. Try the same test while applying a slight bit of resistance to the valve.