Help needed with HVAC vacuum harness

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Help needed with HVAC vacuum harness

Pete Whitstone
Hi all, my 1981 had a completely dead HVAC system when I got it, so I've been trying to determine what's there and what's not. It's an AC truck but a lot of the HVAC stuff (condenser, lines, etc.) was missing. The blower motor wires were not hooked up either. Most of the other important stuff seems to be there though.

I got the blower motor hooked up and working, although there is not much if any difference between the 2 medium speeds, I suspect I just need a new resistor.

The HVAC vacuum lines appear to be mostly in place, but there is no vacuum reservoir or check valve. So it's easy enough to add those. However, the two vacuum lines that come into the engine bay through the grommet on the top of the blower box, are cut/broken right at the grommet. One (white stripe) is for the fresh/recirc door (vacuum motor is still there). The other (black no stripe) is the supply line. I'm looking in the "Body Chassis Electrical" manual on page 36-61-19, figure 12. It shows a 2 line portion of the vacuum harness, presumably with the black and the black/white stripe lines, going up into the area where it would come out in the engine compartment. This part is labelled "Vacuum Harness 19C827" and seems to be the part I need to replace the two broken/cut hoses.

However, searching for that part number shows me all kinds of different parts, usually with 3 hoses, fairly short, and not the right colors. So:

1. Can someone point me to the part number I need, and a supplier who has it in stock
2. Anyone got one off a parts truck they are willing to sell me?
3. Failing #1 and #2, anyone have any tricks or tips for repairing or splicing the existing lines? Or a non-stock replacement that will work?

Thanks!
Pete
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

ckuske
Administrator
I had fun with this recently.  With Gary's help, we took pictures of the different hose bits  for the HVAC vacuum system:

http://www.garysgaragemahal.com/hvac-systems.html

click on Integral A/C->Pictures->Vacuum Lines

Hopefully this helps?
Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread
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Re: Help needed with HVAC vacuum harness

ckuske
Administrator
I needed 827-A, and got a brand new one from Green Sales
Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread
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Re: Help needed with HVAC vacuum harness

FuzzFace2
3. Failing #1 and #2, anyone have any tricks or tips for repairing or splicing the existing lines? Or a non-stock replacement that will work?

Thanks!
Pete
Being I am cheap I pulled the broken plastic line from the grommet and pushed rubber through.

When I added the heater core shut off valve and testing I found my system doors stopped working
I had vacuum on the engine bay side but not on the inside at the plug joining the 2 vacuum harnesses.
I was able to track it down that the plastic supply line broke inside the grommet
That is when I came up with pushing the rubber hose through the grommet.

When on this HVAC vacuum deal.
If trying to track down a vacuum leak and cant find it do you have the tin vacuum can on the fender well for the HVAC system?
Pull it off the fender and pry off the bracket and check it over good. Maybe put a hose on it and put it under water and blow in the hose, any bubbles?
Mine had pin holes on the bottom where the bracket was and the ends. I used fiberglass rosin and coated the can and painted it black put the bracket back on and it is good as new now.

I also the factory check valve did not test good so I picked up 2 from local part store and neither one "checks" when you blow through them also so I kepted the factory one in place and when on the throttle and vent doors move...... oh well.
Dave ----
Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
OK I think I am starting to piece some things together here. More figuratively than literally, but what I've learned so far:

1. The part number shown (19C827) for that little 2-hose connection is not specific to that little segment of the vacuum harness, it's a more general part number that appears to refer to all of the vacuum harness.

2. No one seems to have the entire vacuum harness for sale. When you search for that part number, you might find certain segments of the harness, and usually at very high prices.

3. The correct part number for the vacuum module at LMC truck for my truck (an 81 with AC) appears to be 43-0757, which has all the ports in a staggered line, like this:



4. My truck may have had its control panel swapped for some other year, because the vacuum control on it looks like this:



These two parts are completely incompatible. I found a used HVAC control panel on eBay that fits 80-82, so we'll have to see what that looks like when it shows up hopefully later this week. More to come.

 
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

FuzzFace2
Pete Whitstone wrote
OK I think I am starting to piece some things together here. More figuratively than literally, but what I've learned so far:

1. The part number shown (19C827) for that little 2-hose connection is not specific to that little segment of the vacuum harness, it's a more general part number that appears to refer to all of the vacuum harness.

2. No one seems to have the entire vacuum harness for sale. When you search for that part number, you might find certain segments of the harness, and usually at very high prices.

3. The correct part number for the vacuum module at LMC truck for my truck (an 81 with AC) appears to be 43-0757, which has all the ports in a staggered line, like this:



4. My truck may have had its control panel swapped for some other year, because the vacuum control on it looks like this:



These two parts are completely incompatible. I found a used HVAC control panel on eBay that fits 80-82, so we'll have to see what that looks like when it shows up hopefully later this week. More to come.
Yes you are right on the part numbers. They have a main number that is for all of that part be it for your truck or car and be it for HVAC or something else.
So Ebrake cables for all cars / trucks would have a main number of say (1234-5) but then when for your car or truck would add the rest of the number (1234-5-xxx).

And if you have a part with a number it is NOT a part number but an engineering number.
If looking for said part used you may try that engineering as other think it is a parnt number.
Now it may also help to list it as I think we have a way to find the real P/N.


My HVAC control looks the same as yours, not in a row, and is of the later year but I forget what year mow. I had nothing, the HVAC panel was ripped, yes ripped, from the dash and a member was able to get one from a junk yard for me.

I thought the harness was bad? If so why not run rubber hose to replace the broken plastic lines?
Mine under the dash was still good, it was the engine bay plastic lines that were bad so I ran rubber on the engine bay side into the cab and pushed it on the plastic line.
Dave ----
Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
Thanks for confirming that I likely have a control panel from a newer truck. I have a new control panel on the way which would be correct for the truck and fit the replacement vacuum controller I have. I need to replace the control panel because the part where the cable attaches is broken and I don't see a good sturdy way to fix that piece.

The problem I will then have is that I have the wrong vacuum harness in the truck, it's "plug" goes onto the newer style vacuum controller.

My harness is ok as far as I can tell, except for the part that goes into the engine compartment. So since the plug on the harness will not mate to the plug on the controller, I might ditch the harness altogether and just replace with regular vacuum lines. Or I might just cut off the plug part and splice in vacuum lines that go directly onto the vacuum controller (and then do the same for the engine compartment piece, as you suggest). Once I have all the parts in my hands I can decide what direction to go.

Thanks for the input!
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

salans7
Green Sales Company has 26 of E0TZ-19C827-A which is the part that passes through the A/C box. It is the same from 1980-1986. I can't remember how much I paid for it, but I think it was less than $30.

They also say they have 15 of E0TZ-19C827-C, which is the part you need to fit your replacement control head. But you'll have to call them to inquire about price. In my experience, they've been pretty fair on the few things I've bought from them.
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
I will check that out. I had previously looked at Green Sales web site at the suggestion of Chris (ckuske), but when I searched it said "out of stock". I will look again.
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
Nope, I get "out of stock" on both those part numbers. I wonder what you are doing differently. I go to 'inventory', then put those part numbers in. What are you doing differently to be able to see those parts and quantities?
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

salans7
Don't put any dashes in the number. Also capitalize every character.
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
Good to know, that worked, thanks.

Their website seems full of arcane information I don't care about (memorabilia, customer cars, testimonials) and none of the stuff I do care about (accurate product descriptions, friendly searches, prices, a shopping cart).

I guess a call to them is the only way to place an order, if I decide to go that route?
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

salans7
Yes, only way unfortunately. But most of the NOS parts sites are just as bad. Green's website has been the same site for the last 13 years I've messed with these trucks and NOS parts. Haha.

I don't know how much info they'll be able to give you other than price, as they're mainly sales people and may not know anything about our trucks or the part's application.
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
In reply to this post by Pete Whitstone
Well, I'm happy to report that my system is all back together again and seems to be working. I was able to replace small parts of the vacuum harness with 3/32" hose, add a vacuum ball with a check valve built in, and test the system. I also modified the temperature control cable and got it hooked back up. All the vacuum motors are good and react to the input from the selector on the control panel. So that's a win. Although all the doors move as they should, I do notice a couple things.

First, the air blowing out of the driver side vents does not appear to be nearly as forceful as what comes out of the passenger side. I suppose this is just due to the location of the blower motor?

Second, when in defrost mode or floor mode, air is still coming out of the vents. A small amount of air seems to be redirected to the floor or windshield, but certainly not all of it. Is that normal behavior?

I have ordered all the stuff to get the AC back in the truck, that should be here this week and I will be working on getting that operational over the next few weeks. I'm sure I'll be back with questions. Thanks in advance!
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

Gary Lewis
Administrator
Well done!  

Yes, it is normal for the passenger's vents to blow harder than the driver's vents, surely due to how close the blower is to the vents.

And while it isn't unusual for air to come out of the vents on defrost or floor, it isn't right.  Some door isn't sealing off completely would be my guess.  But if you get enough air out of the defrost or the floor vents then it might not be worth fixing it.

Anyway, good luck on installing the A/C system!  
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Help needed with HVAC vacuum harness

Pete Whitstone
Thanks Gary. I kind of suspected all may not be right after looking at the diagrams in the factory manual. According to them, when the "blue line" motor to the right of the HVAC control panel is activated, it should shut off the vents. The motor is activating, I can see the arm move. But I'm not positive it's connected properly. I'll have to pull a vent out and snake a bore camera down there to make sure the door is moving with the arm.
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

Pete Whitstone
Well, that was fun. I didn't test the heater core for leaks, I don't know why not. But it leaked so I had to replace it. While I had the cover off for it, I could see the door that handles the floor/defrost. I had previously verified that the arm on the vacuum motor moved, but now I could see that the door was just flopping around. So out comes everything that needs to come off to take the dashboard out, that was a learning experience. When I finally got the door out, this is what it looked like.



The thin plastic that was supposed to have served as the hinge was separated. Ok, what do I have around here that I could fix this with? Didn't feel like waiting a week if I ordered one. And that would be if I could even find one, and how old would it be, and how long would it last... nah. So I found a couple small hinges and epoxied them to a piece of aluminum which would serve as the "frame" side of the hinge. I could have dragged out the welder, but thought 5 minute epoxy would be faster. Then I attached the other side of the hinge to the door with a couple small screws.



Put it in the dash and tested it, it works fine. I have the dash back in, but still need to put in the instrument cluster, the radio, and the dashpad. That will have to be for a different day.

Next up, I have most of the stuff I need to put AC back on the car. Still waiting on a condenser, and I will apparently have to have a couple of the hoses (suction and pressure) custom made, as I have not found a source for them. I have the liquid line, but that's the only one. Hopefully I will get all that done before I really really need it, which is probably about a month away.
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

Gary Lewis
Administrator
That's a bummer, but one that many of us have experienced.  Your fix looks good and should last as long as the truck does.  

Good luck on the A/C.  The hoses are frequently an issue, which is why I'm really glad I pulled a complete system out of a newer truck.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

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Re: Help needed with HVAC vacuum harness

Pete Whitstone
To finish up this post, I got a couple hoses made at a local hydraulics shop for $140, then had my mechanic look over my work and see how badly I bunged it up. I had installed the orifice tube upside down, but other than that, he pronounced it good and filled it up with R134. I now have cold air!

One observation he made was that I really need to activate my electric fans when the AC is on. So I ran a wire from the clutch over to the relay that triggers the fans. I put a diode in the wire, so that when the fans came on they didn't back-feed into the clutch and cause the compressor to come on any time the fans come on.

All that works great, and I have used the AC a few times since then, it blows acceptably cold. The biggest thing I notice is that with the AC on (and therefore the radiator fans on), and the blower fan going, my voltmeter is struggling to read 12 volts, when it normally reads a little over 14. I have a 60 amp alternator on it, but who knows what it's really putting out. This is in the daytime, with no headlights and the stereo off. So on a rainy night, with the defrost on, the wipers on, the headlights on, maybe some tunes... that's going to be bad. Time for a new alternator.

I spent a LOT of time researching out 3G alternator upgrades on this site and others. There was a lot of information and conversation, but I was not able to locate the holy grail of "buy this part number and bolt it on, it's plug n play". So I ended up ordering this from Amazon:

https://www.amazon.com/dp/B000PDICF2?psc=1&ref=ppx_yo2_dt_b_product_details

It will be here later in the week or maybe early next week, so we'll see what needs to happen to make it work.
81 F150 Flareside, Edelbrock Pro Flow4 FI, hydraulic roller 351W, E4OD, 4x4, BW1356
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Re: Help needed with HVAC vacuum harness

ArdWrknTrk
Administrator
The 3G alternator is not really an option if you install electric fans.(though I don't know what yours draw)
This is why Ford started installing the 130A alternators in the early '90's and still holds true today.

Not because they can put out up to 160A (momentarily) but because they'll put out 80-90A at idle without melting the rectifier board and windings.
That's more than the 2G's 65A at max output.

The 3G has internal fans front and rear.
They move a huge amount of cooling air through the case compared to the external fan on a 1 or 2G alternator.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.
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