The valve that is supposed to open to allow coolant flow to the rear is located under the hood on left side of engine behind the coolant overflow jug and windshield washer jug..

 

So, do I have to replace one, or the other, or both, or all three. I am Googling how to remove the coolant expansion tank / windshield washer tank. I want to get in there and take a look. Would I hold any vacuum if the lines were leaking at the actuator or bypass?
I do get panel heat, since I fixed the vacuum line to the round storage vessel.

*** All three of these parts have notes regarding the YF7 code I do have on my door panel SERVICE PARTS IDENTIFICATION build sticker ***

ACDelco 15-5551 GM Original Equipment Heater Bypass Valve.
Notes: AUX HTR,RR(C36), EXCEPT RECREATION UPFITTER PKG(YF7)

ACDelco 15-5586 GM Original Equipment Auxiliary Heater Water Shut-Off Valve.
Notes: RECREATION UPFITTER PKG(YF7)

Dorman 600-104 Actuator
Notes: RPO Code C36 (Auxiliary Heater), Exc. Recreation Vehicle Upfitter Package (YF7)

Nice diagram here!
http://nemiga.com/img/catalogs/epc/gm/erapa_1/14708.png

 

*** All three of these parts have notes regarding the YF7 code I do have on my door panel SERVICE PARTS IDENTIFICATION build sticker ***

In that case, you are probably dealing with an aftermarket system. The factory rear heat is directly behind the drivers seat and it ends there, and the factory rear A/C is in the back by the door.

 

The unit is all the way in the back near the rear double doors, Driver's side. I imagine it has two exchangers, AC and heat. That is why there are 4 hoses likely?

 

The unit is all the way in the back near the rear double doors, Driver's side. I imagine it has two exchanges, AC and heat. That is why there are 4 hoses likely?

2 lines for the A/C and 2 for the hot water.

 

The unit is all the way in the back near the rear double doors, Driver's side. I imagine it has two exchangers, AC and heat. That is why there are 4 hoses likely?

Yes, exactly, but it's going to be an aftermarket modification/system. Warm up the engine, turn on the heat and see if the lines get warm. Oh and post some pictures of what you have, it's nice to see how different conversion companies did things.

 

This sounds like it is going to be interesting.

Stock Heater is directly behind Driver's seat by the Fuel Filler.
Stock A/C is by the Back Door on Driver's side.

Mike

 

So here is where the aftermarket system clamps onto the factory stuff. They were ice cold after a good drive. These two are slightly "softer" to a light squeeze than the other two, which I think makes them the water hoses and the harder ones are the AC.
https://goo.gl/photos/vvnprWdzadjGjzo9A" onclick="window.open(this.href);return false;
After passing through the frame cross member, the pair take a distinct 90 degree turn and head over the trans to the passenger's side.
https://goo.gl/photos/a738Qxt54AB2gQTXA" onclick="window.open(this.href);return false;

Up under the hood, I have this:
https://goo.gl/photos/tYrBuqyocXTsoAKL6" onclick="window.open(this.href);return false;
which I think is one of these: ACDelco 15-5586 GM Original Equipment Auxiliary Heater Water Shut-Off Valve

I also have this:
https://goo.gl/photos/8L7KdRKGZTo1JeG67" onclick="window.open(this.href);return false;
Which is I believe the ACDelco 15-5551 GM Original Equipment Heater Bypass Valve, or as I will refer to it, the 6 headed Hydra.

What is not there is the Dorman 600-104 Actuator, or the receptacle of the Accessory heater that perhaps the mystery plug goes to (an earlier post of mine). https://www.astrosafari.com/viewtopic.php?f=76&t=107633" onclick="window.open(this.href);return false;

The blue line is silicone vacuum line I put in from the three way:
https://goo.gl/photos/ZQodw5LVP26UJxqC6" onclick="window.open(this.href);return false;
to the vacuum reservoir.

The vacuum line branching to the right and the two shiny(er) black plastic hard lines go together through the fire wall.
One of the hard lines goes to the Aux Shut-off, one goes out of to the bottom of the Hydra, and the third connects to the 3-way. The all go into the panel on the dash I suppose. The regular heat works fine. The Aux Shut-off vacuum line pulls air when the knob is positioned on "panel" heat. I think the correct course of action is to replace the Aux heater water shut-off valve. If the valve is getting vacuum, and the lines stay cold, it must not be opening. Well, unless there is some other horrendous blockage problem. I suppose I could take of the hose clamps under the van and see if I can put my lips on the hose and blow out the old coolant :hand:
And get some DexCool to refill the inevitable spills.

on the other hand, what is the diameter of the hose on the ACDelco 15-5551 GM Original Equipment Heater Bypass Valve?
I may just stick a piece of metal pipe in the place of it and block the vac line. What size pipe would that need to be?
Presto save $30 and have the heat on back there all winter

 

I originally had a piece of gas pipe like goes into your stove for that. It is tight but it will screw in there. Then lumpy had the ball valve deal. I had to have one of them.

 

Presto save $30 and have the heat on back there all winter

For 3 or 4 months. Then you will be going into summer with no way to shut the heat off!

 

Presto save $30 and have the heat on back there all winter

For 3 or 4 months. Then you will be going into summer with no way to shut the heat off!

The core will get hot, but the blower still turns off.

 

Presto save $30 and have the heat on back there all winter

For 3 or 4 months. Then you will be going into summer with no way to shut the heat off!

The core will get hot, but the blower still turns off.

And you still get radiant heat from the core adding to the radiant heat from all the glass.
As a temporary fix to get home or a to garage I have no problem with it. But to do it just to put off fixing properly? Odds are the heat won't get shut off anyways. So why not just do it right and stop worrying about it?
The control valves are not that expensive! Those pennies are going to get tired of getting pinched and stop working all together. Just ask my former boss!

 

Doin' it right: put in a new 15-5586 Auxiliary Heater Water Shut-Off Valve.

I am confused however, and not optimistic that this solved my problem, because this part is by default set as an open valve. The vacuum closes it. So if it failed the heat would be on all the time. I checked that the heater core has no blockage. The coolant looks good.
I have not run the van to get it up to operating temperature today, just came inside with this realization about the valve effectively acting as a straight pipe.

So what is the real reason my rear heat core is not heating up?

 

There seems to be about 3 or 4 plumbing schemes for various year Astrofari's. My 89 stock system allowed hot water to always flow through the FRONT heating coil. The vacuum operated valve allowed or disallowed water to flow to the REAR heating coil. But there was always hot water circulating through the front coil. That area of the cabin got hot whether you had the heat turned on or not. When you turned the front heat ON, yit simply opened the air damper doors near the passenger feet area.

Other year valves shut off the water to this or that coil.

I installed a mechanical shut off ball valve to the SUPPLY side of the front coil. But then discovered that hot water was still migrating up the RETURN side. So I installed a valve in both lines. In the non heating week in Phoenix, I manually open the two valves under the hood. Then when summer hits again, six days later, I close them again.

Lump

 

ummm, rear heat works now. Don't understand why, but happy.

 

It was a loose hose clamp. CC and I came over last night and fixed it.

Lump

 

:rockon: :rofl: :ty: :thumbup:

astrofaries!