heater help

[70stroker]

Guys i have a 86 chevy 4x4 shortbed. Its starting to get colder down here and I think about now is a good time to start figuring this all out. the heater gets warm but the blower doesnt seem to be putting out much.

You can hear the blower motor step up its speed with each and every selection you go up on the speed, But you cant really feel much of a difference in flow from the low up to high.

Now this truck did sit for about a year before i got it. So it could be something in the ducting, such as a nest or insulation, but im not 100% sure. If you guys think this also can anyone tell me the best way to go about taking the ducting out and installing it to make sure it all works again. Pictures would be helpful alos.

Thanks

[HOGDADDY]

Do you feel it blowing any from the lower heater vent just above the tranny hump in floor?

The heater doors are all vacuum operated are you sure you have vaccum from the round ball on driver's side under hood?

I recently rebuilt my heater box with new core and cleaned it up. It now heats too good. I didn't take any pics sorry.

Actually I rebuilt the whole ac/heat system put a newer cab on frame cause tree fell on old cab.

[70stroker]

were exactly is the ball? Or better yet where under the dash can i check for vacuum (in other words where does the line coming from this ball attach to under the dash) Should i have engine vacuum at this line?

thanks

[old Rusty C10]

do you have air conditioning? if its a non ac from factory there is a heater door that is moved via cable that could be not closing all the way

[HOGDADDY]

Originally Posted by 70stroker

were exactly is the ball? Or better yet where under the dash can i check for vacuum (in other words where does the line coming from this ball attach to under the dash) Should i have engine vacuum at this line?

thanks

The Ball is a black plastic softball size thing under hood by driver's side firewall. Yes engine vacuum or do you not have ac like rusty said then it wouls be cable operated.

[70stroker]

no i dont have ac, but the box and the control unit do have ac options, so it came from the factory with ac but the previous owner removed the compressor and condenser.

[babyJay]

I thought the ball was for cruise control.....

[85gmcguy]

I don't have cruise but I do have the "ball". Maybe a vacuum reservoir?

[old Rusty C10]

with the compressor and condensor removed it should operate off of vacuum. I would remove the glove box and with the fan on low motor running id go listen for any vacuum leaks .I would also check up by the selector switch too because its possible for it to dry rot or leak there too. I dont have any pics of an air conditioned box but you can prolly move the air door over so its fully open. IM not sure if there is any other threads on this subject

[70stroker]

Alright guys heres what i found.

I do have the ball I can only see or feel one nipple on it and thats on the top. My question is if vacuum is supplied to this "ball" how does it help the vents with no outlet source?

I do not have vacuum at that ball, I tracked the vacuum line over the brake booster and right before the firewall curves back it connects to a switch, on the other side of this switch it has a electrical connector. what would this be for?

Third i did find a vacuum line going into the firewall by the ac heater box and it does have a vacuum source. Is this what runs the vents?

Last thing i did was put my head down by the brake pedal and watch the vent door move while i changed the selector location. With it on vent it blows out of the vent and very little to none at the bottom by the trans tunnel. With the selector on "heat" it blows very hard at the bottom by the trans tunnel. With it in defrost it still blows hard at the trans tunnel, also you dont see the door move while going from heat or vent to defrost. Whats this mean? I assume that door should move when going to defrost, and thats probably my issue but i dont know what the next step would be.

Thanks in advance

[HOGDADDY]

Type in your info on your truck on this site. They have a good diagram showing heater box parts and all assosciated with it.

http://www.gmpartsgiant.com/

The heater box has 2 vacuum valves one opens for defrost I think maybe one hose came off or diaphragm is bad.

[70stroker]

Alright guys i went and messed around with it a little more, what i found is a bunch of muddobbers nest in the ducting along with some insulation. Needless to say removing that improved the flow alot.

I also found out that the door that is suppose to move and block air flow to the floor and direct it up to the defrost is not moving, I can manually pull that door so it shuts off air flow to the floor and it pushes alot of air to the defrost.

Ill be honest and say defrost is my main concern, so if i have to i will wire that door so air always goes to the defrost, but if i can fix it to work like factory with your guys help then i will do that.

So what i found is i am not getting vacuum to the diaphram right above the gas pedal that controls the floor and defrost door. I tracked it down to the back of the selector panel along with about 5 other lines at the back of the control. My question is if the control panel will direct flow from the floor to the vents as it should with the move of the selector could i still possibly have a bad control selector panel?

or could that switch at the back of the panel be bad? Can it be replaced?

Where should i go next?

Thanks

[HOGDADDY]

All the selector does is move a wheel to the correct port for vacuum kinda reminds me of a revolver gun and the temperature selector is cable controlled to open up the heat door I believe.

This company has the diaphragms available also.

http://www.oehq.com/index.cfm?index=yes

[motornut]

you may hear the rubber edge of the flap inside moving when it hits the end of it's movement(cable drivin)
how is the truck running any chance a vac leak?
if you want to check the floor/def flap you can ez with temp air line and blow or suck to move the flap,inside that flap it has three holes to allow a choice of some air always to go up or down, or all air up or all air down.

[kenm78]

Not trying to steal this thread. But so that I am understanding everything. The above pictured valve controls the threaded rod that has the white clip in the above picture right?

Next if that threaded rod moves all the way left and center for vent and floor but not all the way right for defrost, it tells me the valve is bad correct?

[qu1cks1lver56]

that hose came off of mine, found it laying in the floor the other day.

[kenm78]

Mine is still connected and I do have vacuum to mine.

[motornut]

Originally Posted by kenm78

Not trying to steal this thread. But so that I am understanding everything. The above pictured valve controls the threaded rod that has the white clip in the above picture right?

Next if that threaded rod moves all the way left and center for vent and floor but not all the way right for defrost, it tells me the valve is bad correct?

the white clip(broken in pic) chooses ac front vents or floor/def then
the valve in pic chooses floor or def

these two pieces would be amost 3 feet apart

[motornut]

Originally Posted by kenm78

Mine is still connected and I do have vacuum to mine.

maybe try moving the valve by blow or suck a temp line on it to see if the bellows in the valve is working or maybe the clip inside on the flap came loose

[kenm78]

Ok, I pulled the front box off to reveal the door in the lower picture above. The small white piece that is bolted to the door is broken on mine. I will get that fixed and go from there. I was unaware there is anouther vacuum actuator behind the heater box.

[HOGDADDY]

Classic parts sells that white piece btw I bought one and it worked fine.

[kenm78]

Originally Posted by HOGDADDY

Classic parts sells that white piece btw I bought one and it worked fine.

Did the diverter clip come with the pin hole already drilled in it for the vacuum can bracket?

[kenm78]

For $2.49 I bought 2 becouse shipping was 8 bucks!! Hopefully this will be the fix!

[HOGDADDY]

Originally Posted by kenm78

Did the diverter clip come with the pin hole already drilled in it for the vacuum can bracket?

Yes its drilled but from the pics Classic has of item it looks like it don't.
just a bad pic I guess.

[kenm78]

Got it fixed! The small white piece on the door flap above was broke and the cause of poor defrost. Thanks for the help.