Vacuum Controlled Heater Core Valve

[FuzzFace2]

The problem we have is that we would like the valve to work in both Vent and Max A/C. Unfortunately our control doesn’t give a vacuum signal for both of those situations and not others, as shown by a table from the 1981 shop manual, below.

My plan is to use connection #1 on the HVAC control, which isn't used. As shown below it provides vacuum on both Vent and Max, but not on Norm. The plastic on the control isn't drilled, and there's no hose on that port of the connector, but I think that should be easy to fix However, that is for a 1980/84 control, and I haven’t looked at a 1985/86 control to see if that is possible with them.

http://forum.garysgaragemahal.com/file/n4287/E019DF4B-2DBB-4F62-9D25-5D6288D06D1D.jpeg

I hate to bring this up being so old but it is time to do this to my truck and have a question.

First I could not find this in Documentation did it get left out? Maybe in the "up grade: area?

If I under stand the control using the #1 port we have the water shut off in AC max & vent, is this true?

What would happen if we tee'd into port #3? We then also have the water off in normal would this be a issue?

I am also thinking if the water was off in any of the control settings moving the temp control would do nothing right?

Dave ----

 

[Gary Lewis]

The problem we have is that we would like the valve to work in both Vent and Max A/C. Unfortunately our control doesn’t give a vacuum signal for both of those situations and not others, as shown by a table from the 1981 shop manual, below.

My plan is to use connection #1 on the HVAC control, which isn't used. As shown below it provides vacuum on both Vent and Max, but not on Norm. The plastic on the control isn't drilled, and there's no hose on that port of the connector, but I think that should be easy to fix However, that is for a 1980/84 control, and I haven’t looked at a 1985/86 control to see if that is possible with them.

http://forum.garysgaragemahal.com/file/n4287/E019DF4B-2DBB-4F62-9D25-5D6288D06D1D.jpeg

I hate to bring this up being so old but it is time to do this to my truck and have a question.

First I could not find this in Documentation did it get left out? Maybe in the "up grade: area?

If I under stand the control using the #1 port we have the water shut off in AC max & vent, is this true?

What would happen if we tee'd into port #3? We then also have the water off in normal would this be a issue?

I am also thinking if the water was off in any of the control settings moving the temp control would do nothing right?

Dave ----

No problem bringing it up. If you tap into #3 then you won't have any temp control. And, as you said, the temp lever would do nothing.

And it is in Documentation/HVAC/HVAC Systems and on the Heat Shut-Off tab. Is there a better place?

[FuzzFace2]

No problem bringing it up. If you tap into #3 then you won't have any temp control. And, as you said, the temp lever would do nothing.

And it is in Documentation/HVAC/HVAC Systems and on the Heat Shut-Off tab. Is there a better place?

:nabble_smiley_blush:I must not have looked that good sorry.

That is a good place as any I guess. I just need to open my eyes is all.

I do have a add on for the vacuum valve part number.

You list a 2 port valve and that would be good for 99% of the trucks but I am that 1% it does not.

Because I have a 300 six and running EFI exh. manifolds I need to heat the intake manifold so a 4 port valve that bypasses the heater core but keeps the hot water flowing is what I need.

The valves below will do this.

PN: 74809 Four Seasons

or

NAPA PN: BK6601294

I hope to pick one up ASAP as the vents are blowing hot air and don't need AC that is not working yet.

Thanks again

Dave ----

 

[Gary Lewis]

No problem bringing it up. If you tap into #3 then you won't have any temp control. And, as you said, the temp lever would do nothing.

And it is in Documentation/HVAC/HVAC Systems and on the Heat Shut-Off tab. Is there a better place?

:nabble_smiley_blush:I must not have looked that good sorry.

That is a good place as any I guess. I just need to open my eyes is all.

I do have a add on for the vacuum valve part number.

You list a 2 port valve and that would be good for 99% of the trucks but I am that 1% it does not.

Because I have a 300 six and running EFI exh. manifolds I need to heat the intake manifold so a 4 port valve that bypasses the heater core but keeps the hot water flowing is what I need.

The valves below will do this.

PN: 74809 Four Seasons

or

NAPA PN: BK6601294

I hope to pick one up ASAP as the vents are blowing hot air and don't need AC that is not working yet.

Thanks again

Dave ----

I added that valve to that page. Thanks!

[FuzzFace2]

I added that valve to that page. Thanks!

Your the man

Dave ----

[81f100custom]

Your the man

Dave ----

My truck is a 1981 but has a 1985 complete factory A/C system in it. I had considered doing this but haven't as of yet. My plan was to get a vacuum to close valve and to tee into the black/white vacuum line on the outside recirculate door vacuum motor which is already right there where you would need it to feed the heater valve. It would only shut off the water in the Off and Max A/C mode only. But as Gary mentioned he wants it shut off in the vent mode also so not good for that. Myself I did not want it shut off in the vent mode as I use mine a good bit when it is cold out to blow heat through the panel vents so was not wanting to keep the hot water out for that reason on vent. Here is a link to some of the vacuum to close valves I was considering.

https://www.4s.com/en/ecatalog?part=Vacuum%20Closes%20Non-Bypass%20Heater%20Valve&type=p

[ratdude747]

My truck is a 1981 but has a 1985 complete factory A/C system in it. I had considered doing this but haven't as of yet. My plan was to get a vacuum to close valve and to tee into the black/white vacuum line on the outside recirculate door vacuum motor which is already right there where you would need it to feed the heater valve. It would only shut off the water in the Off and Max A/C mode only. But as Gary mentioned he wants it shut off in the vent mode also so not good for that. Myself I did not want it shut off in the vent mode as I use mine a good bit when it is cold out to blow heat through the panel vents so was not wanting to keep the hot water out for that reason on vent. Here is a link to some of the vacuum to close valves I was considering.

https://www.4s.com/en/ecatalog?part=Vacuum%20Closes%20Non-Bypass%20Heater%20Valve&type=p

On my 1995 Ranger this is how the heater core valve is used... only closes when the system is off or when Max AC is on, just like the recirculate door. Pretty sure they are on the same vacuum circuit.

The heater hoses are the same size too... so such a valve would be a direct fit (when closed, it allows the coolant to circulate, so one always has coolant flow). They do tend to blow up and leak if the rad cap doesn't properly regulate the pressure though (they're plastic).

[FuzzFace2]

My truck is a 1981 but has a 1985 complete factory A/C system in it. I had considered doing this but haven't as of yet. My plan was to get a vacuum to close valve and to tee into the black/white vacuum line on the outside recirculate door vacuum motor which is already right there where you would need it to feed the heater valve. It would only shut off the water in the Off and Max A/C mode only. But as Gary mentioned he wants it shut off in the vent mode also so not good for that. Myself I did not want it shut off in the vent mode as I use mine a good bit when it is cold out to blow heat through the panel vents so was not wanting to keep the hot water out for that reason on vent. Here is a link to some of the vacuum to close valves I was considering.

https://www.4s.com/en/ecatalog?part=Vacuum%20Closes%20Non-Bypass%20Heater%20Valve&type=p

Well ran into a problem like you my controls are from a newer truck and I forgot that till I pulled the dash & part of the HVAC controls apart and could not figure what port had to be hooked up.

When I check here it all turned to

But unlike you I don't want heat out the dash vents when on vent as I don't have AC installed in the truck yet and the real reason I was doing this.

So now I got to figure out what to do to make this work like the early trucks?

Is there a pin out of the ports for the later trucks like the 80-84 trucks?

I know it is posted I can swap in the early controls but it took a while to find this with a lot of help from Jonathan and it works like it should so hate to go changing it.

Dave ----

[FuzzFace2]

My truck is a 1981 but has a 1985 complete factory A/C system in it. I had considered doing this but haven't as of yet. My plan was to get a vacuum to close valve and to tee into the black/white vacuum line on the outside recirculate door vacuum motor which is already right there where you would need it to feed the heater valve. It would only shut off the water in the Off and Max A/C mode only. But as Gary mentioned he wants it shut off in the vent mode also so not good for that. Myself I did not want it shut off in the vent mode as I use mine a good bit when it is cold out to blow heat through the panel vents so was not wanting to keep the hot water out for that reason on vent. Here is a link to some of the vacuum to close valves I was considering.

https://www.4s.com/en/ecatalog?part=Vacuum%20Closes%20Non-Bypass%20Heater%20Valve&type=p

Well ran into a problem like you my controls are from a newer truck and I forgot that till I pulled the dash & part of the HVAC controls apart and could not figure what port had to be hooked up.

When I check here it all turned to http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/poo-23_orig.png

But unlike you I don't want heat out the dash vents when on vent as I don't have AC installed in the truck yet and the real reason I was doing this.

So now I got to figure out what to do to make this work like the early trucks?

Is there a pin out of the ports for the later trucks like the 80-84 trucks?

I know it is posted I can swap in the early controls but it took a while to find this with a lot of help from Jonathan and it works like it should so hate to go changing it.

Dave ----

To bring this later picture to the end here of the 85-86

So it looks like if you have the 85-86 control you can only tee into the white line and supply vacuum to the valve when only in MAX AC

So guess that is what I will do as the AC is not working at this time I can use MAX AC to blow air into the cab. It is better than what I have now as hot air blow in all the time.

Thanks guys

Dave ----

[1986F150Six]

To bring this later picture to the end here of the 85-86

So it looks like if you have the 85-86 control you can only tee into the white line and supply vacuum to the valve when only in MAX AC

So guess that is what I will do as the AC is not working at this time I can use MAX AC to blow air into the cab. It is better than what I have now as hot air blow in all the time.

Thanks guys

Dave ----

I do not know if this will help, but I installed an vacuum controlled cutoff valve in the heater circuit on my son's 1984 F150. A "T" was installed in the vacuum line which feeds the servo controlling the door for allowing fresh air [near the passenger inner fender]. The heater is "on" except when the A/C is placed on "MAX COOL".