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Heater only blows at floor

If you remove the vacuum hose from pod 21, door 22 should block floor opening. This the natural position with everything off.
If you need to prop it open either the vacuum is miss routed, or there is a physical issue in the plenum. The vacuum pod #21 should not have vacuum applied when defrost is selected
 
@Irishmic here is what I have for you .. as I mentioned mine is a 85 k5 with 6.2 diesel ... the vacuum harness is factory original with C60 AC. The Diesels did not have a Vacuum Canister as the Vacuum came straight from the Vacuum pump. With the Gas Engines the vacuum comes from the engine via the vacuum Pod / Ball / Canister whatever.

I am sending you some pictures from my Blazer and schematics from the GM Manuals .. Wes sent some and I am resending one that verifies the line color. I am also sending a schematic that shows a defroster pod that has two lines in case yours has one ... mine only has the one hose to the defroster. I hope this helps you get yours back in order.

You can order a 1/8 vacuum tubing kit as follows if you want ... I ordered one thinking I would change out my harness, but after inspecting mine thoroughly, I opted not to change it out. EDIT # 1 ... The Colors are not an exact factory match but you can set your own scheme and determine which color you want to control what function.... try to stay as close to factory as possible ... i.e. orange to orange ... blue to blue .. black to black .. etc.



01-IMG_7778.JPG02-IMG_7775.JPG03-IMG_7770.JPG04_Back of HVAC Vacuum Controller - Marked - P1.jpg05_Fig 20 C-K AC Vacuum Schematic.jpg06_RPO C60.jpg07_Defrost has two ports.jpg
 
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85-K5Blazer said:
@Irishmic here is what I have for you .. as I mentioned mine is a 85 k5 with 6.2 diesel ... the vacuum harness is factory original with C60 AC. The Diesels did not have a Vacuum Canister as the Vacuum came straight from the Vacuum pump. With the Gas Engines the vacuum comes from the engine via the vacuum Pod / Ball / Canister whatever.

I am sending you some pictures from my Blazer and schematics from the GM Manuals .. Wes sent some and I am resending one that verifies the line color. I am also sending a schematic that shows a defroster pod that has two lines in case yours has one ... mine only has the one hose to the defroster. I hope this helps you get yours back in order.

You can order a 1/8 vacuum tubing kit as follows if you want ... I ordered one thinking I would change out my harness, but after inspecting mine thoroughly, I opted not to change it out. EDIT # 1 ... The Colors are not an exact factory match but you can set your own scheme and determine which color you want to control what function.... try to stay as close to factory as possible ... i.e. orange to orange ... blue to blue .. black to black .. etc.



View attachment 428731View attachment 428732View attachment 428733View attachment 428734View attachment 428735View attachment 428736View attachment 428737
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Wow, this is amazing and I can not thank you enough.

I know this is not just helpful for me but I'm sure many others will be able to use this very detailed and the pictures are such a great reference.

This is great, literally made my week!!!
 
it sure is, but if it did, the system should still defualt to blowing out the defrost vents. This was the way it was designed, for any failure to default to defrost for safety. Don't care if your cold as long as you can see where your going.
 
Wes Harden said:
it sure is, but if it did, the system should still defualt to blowing out the defrost vents. This was the way it was designed, for any failure to default to defrost for safety. Don't care if your cold as long as you can see where your going.
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When I installed a new heater core I made sure all my actuators and vacuum lines where connected properly, but when I connect my vacuum source to the engine the engine starts to run like it has a vacuum leak. The only place it could be coming from is the actuators.
 
Just wanted to mention that the dash vents have a habit of taking on foreign objects. Maybe you never put ink pens and bobby pins on the dash, but it doesn't mean a previous owner didn't. And sometimes that stuff can move around years later.
 
@1-ton ton The vacuum reservoir ball is while and sound with good vacuum lines.
With the spaghetti sized vacuum in the dash, would be a sensitive engine to notice a leak. Still possible.
Process of ellemination. Remove and plug one line at time.
If no change after all the actuators, is probably the rotary switch
 
Wes Harden said:
@1-ton ton The vacuum reservoir ball is while and sound with good vacuum lines.
With the spaghetti sized vacuum in the dash, would be a sensitive engine to notice a leak. Still possible.
Process of ellemination. Remove and plug one line at time.
If no change after all the actuators, is probably the rotary switch
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Those actuators are hard to get at, which is why I went over them in detail while I had the HVAC box out of my square body installing the new heater core. I have the same situation as the guy who's thread I am hijacking. The vents are stuck on floor only. That is OK for now because winter is coming, and I like having the heat come from the floor.
 
1-ton said:
When I installed a new heater core I made sure all my actuators and vacuum lines where connected properly, but when I connect my vacuum source to the engine the engine starts to run like it has a vacuum leak. The only place it could be coming from is the actuators.
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Are you sure your vacuum Ball or Canister does not have a leak in it ? Maybe a hair line crack ??? the Vacuum balls are not that expensive to replace ... not sure about a canister ... Engine Vacuum should go from Manifold to "holding tank" to vacuum rotary control on HVAC switch ...

Just some additional thoughts ...
 
1-ton said:
Those actuators are hard to get at, which is why I went over them in detail while I had the HVAC box out of my square body installing the new heater core. I have the same situation as the guy who's thread I am hijacking. The vents are stuck on floor only. That is OK for now because winter is coming, and I like having the heat come from the floor.
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You're not hijacking, don't worry man. But ya we have the same issue. Unless I prop open the vent itself. It will default to floor. Lucky for me I was able to so I can now u fog it. If not I would not be able to drive it.
 
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