Heater Valve
 

Does hot coolant supposed to flow to the heater core ALL the time on the Bullnose trucks?

I noticed an older 1979 F150 had a heater valve inline with one of the heater hoses to shut off the hot water through the core when you are using the air conditioning. I can see how that would be more efficient and make the air cooler.

I don't see one at all on my 1985 F150 with factory A/C, just two heater hoses running from the intake to the heater core, and another from the heater core to the water pump.

Does my truck supposed to have this valve? :-huh

No valve. Some Fords had the valve, some didn't. It depends on the design. The old mustangs don't have a valve.

Some people add one in to help their A/C when the doors get leaky. I will see if I can find the article, I added one on my 89. It's a pretty cheap modification.

Here's the article. I was surprised how cheap the valve was.

Heater Core Bypass

Wow, that guy did a lot of plumbing with ball valves and everything just to add a filter.

I've heard of the Ranger mod, but never felt the need.
Having the vacuum hooked like that would bypass my heater core on real cold mornings when I have the control set to recirculate, trying to warm up the air in the cab.
Maybe not an issue for those in warmer climates.

Yea, some of those guys are big rig diesel guys, and they have that type of stuff on those trucks, so they transfer those ideas down to the "little" trucks. Some of those filters have chemicals in them that slowly release into the coolant to keep things corrosion free. Like I said, that's all big rig million mile stuff.

1973/79 F100/350 & 1978/79 Bronco only have a vacuum controlled heater water valve (D4AZ-18495-A) IF factory installed integral A/C or Hi/Lo Comfort Vent System is present.

No heater water valve is illustrated/listed for 1980/89 F100/350 & Bronco (except w/auxillary heater).

Left lower pic: 1980/86 F100/350/Bronco heater hoses / Right: Applications for 18495 heater water valves ~ A: Aerostar; B: Bronco II; E100/350: Econoline; R: Ranger; U150: Bronco.

Jim,

One can put a "tee" in the vacuum line which goes to the servo motor on the firewall on the passenger side. This motor closes the door when "max a/c" is used. The other side of the "tee" is connected to a vacuum controlled valve spliced into one of the heater hoses. This way, when vent, heat or regular a/c is selected, there is heat available, but when the selector is set for max a/c, the heater core is bypassed.

It works!

I have no A/C...

But when I want my cab warm, I want to recirculate the already lukewarn cabin air... not send subzero outside air through the heater core for only one pass.
On my control panel this is labeled 'outside air- off'

How about removing the vacuum control motor and using a manual choke cable to hook up to the arm on the valve. Then you'd have manual control over the valve and could close it in the summer and open it in the winter.

Or, you could add a Dorman 911-603 Vacuum Switching Valve for Toyota Evap system and wire it up so it cuts off vacuum except in Max AC mode.

I think I would just go to a cable operated 5/8" heater valve if it were me.

http://www.ebay.com/itm/Four-Seasons-Cable-Operated-Pull-to-Open-Heater-Valve-5-8-74828-/111119733090?pt=Motors_Car_Truck_Parts_Accessories&hash=item19df409162&vxp=mtr
Cheap and not much to go wrong.
I've "fixed" the brittle vacuum line to that flap too many times.

Does it matter that there's no flow though the heater hoses? The Explorer/Ranger valve loops the coolant back to the engine.

My 460 has a bypass hose from the intake back to the pump.
It doesn't matter one bit if there is water flowing through the core (or recirculating through the cutoff)
Besides it would ONLY matter before the thermostat opens.
It is nice that I get heat before the engine reaches operating temperature.

It has been hot and sticky here.
I am rockin' the 2x60 A/C :D

On certain setups it does matter, others not. For instance the guy with the coolant filter it would matter, since it would stop the flow in the filter.

Some of the older Fords had a clip that put the heater hose against the choke housing on the carb, it would matter then. Anything that is tied into the heater core loop would make it matter. On my truck I used to have electric fans. I put the temp sensor inline with the heater hose with a couple of fittings, so it would matter in that setup also.

But most vehicles with just plain heater hose going to the core don't care if there is flow there or not.