Heater valve bypass to fix "heated dashboard vents"?

[JWA]

Originally Posted by jblaze5779

Why couldn't I just use a manual quarter turn ball valve? I rarely ever use my heat here.

You could do that----its be far the easier way to go for this fix or mod. The only downside is when warm coolant isn't present in the heater core your windshield defrost mode may be much less effective if you'd want anything less than full cooling in that airflow stream.

I've been working on a relatively simple system were vacuum operated valves are inserted into the coolant flow, vacuum signals being independently controllable with electric switches inside the front cabin. Living in Ohio with a full 4 seasons my concoction is effective, ready year-round and very convenient too.

[jblaze5779]

I went ahead and just ordered a normally closed 12VDC actuated ball valve from amazon. It was $38. I'll just run it off a switch. If I want heat or defroster, I'll flip the switch to send power to the valve. Most times I probably wont use it. I imagine it'll decrease warm up time also during the winter.

[arctictraveller]

Does anyone know if there is a down side to completely stopping return coolant flow back to the engine? Is that coolant used to cool any part of the block or head after it departs the heater core?

[jblaze5779]

Originally Posted by arctictraveller

Does anyone know if there is a down side to completely stopping return coolant flow back to the engine? Is that coolant used to cool any part of the block or head after it departs the heater core?

I don't see how it can be. You're only blocking the coolant from circulating through the heater core. The engine should still be fine since the majority of the coolant will still be routed through it.

I thought about just putting a clamp on the line and seeing if it made any difference on my a/c before buying the valve. I need all the help I can get down here.

If you start overheating though it is good to be able to turn heat on full blast and utilize the heater core as extra cooling though so a valve is nice to have.

[MadScience]

FWIW I recently installed a bypass valve and happy with the results. This is the valve I used:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I looked at the coolant routing on the v10, and decided I didn't want to spend the time to truly understand it. So I just went with the bypass rather than something that blocks flow completely.

I attached the vacuum input to the max AC recirculation door. I may yet hack something up for the vent setting, but honestly I can also just run the AC for that case. I generally don't mind the drying effect.

Somewhat ironically this is directly related to installing the agile valved fox shocks. At 75 mph in 114 degree weather the ac vents were blowing 75 degree air while the van was much warmer than that inside. Coolant temp was at 220(+?) degrees. Slowing down helped, and before the shocks I would not have been driving that fast, but now that I can....

I've not been back out on i5 on a hot day yet, but I've seen a huge drop (10-20 degrees) in vent temperature in other situations, even fairly hot ones.

Total install time was about an hour. Edit: I needed exactly 5 feet of vacuum hose, I'd buy 7 feet if I did it over. Routing through the fender, above the fender liner and in right by the fuel cut off switch is pretty simple. Put a pan under the van, I lost about a half gallon of coolant just cutting the lines and being quick with the connections. I didn't have clamps big enough for those lines, so I did it that way. Worked fine, but the coolant is under a little bit of pressure there. Probably just from what's in the core and above it, but it gushed both ways.

[arctictraveller]

Originally Posted by jblaze5779

I thought about just putting a clamp on the line and seeing if it made any difference on my a/c before buying the valve. I need all the help I can get down here. .

I've done just that using a pair of vicegrips with some cardboard over the hose. It definately made a difference in the temp of the air coming out of the vents, perhaps an additional 10deg's cooler. As for cutting off the entire flow , I've heard that on some engines (not neccessarily a modular Ford though) that completely blocking off the flow can cause a hot spot in either the block or the head. I don't know if this is true or not, but I didn't detect any problems when I did it, but I was hoping someone would be able to confirm one way or the other.

[MadScience]

Originally Posted by arctictraveller

I've heard that on some engines (not neccessarily a modular Ford though) that completely blocking off the flow can cause a hot spot in either the block or the head. I don't know if this is true or not, but I didn't detect any problems when I did it, but I was hoping someone would be able to confirm one way or the other.

I tried to answer that question for myself, and the best I found was this image which is for a bare chassis (class A) application of the v10:



I have the factory service manuals for my '99 and nothing in them is nearly as useful as that diagram.

It's helpful in that I was at least able to determine the direction of the flow from it. I don't however know what some of the manifolds are and how they function. If they are all just open areas, it's probably OK. If not, perhaps not. It was certainly easier to just install the bypass (which is plenty cheap) than to pull one of them apart and try to understand this in detail.

[jblaze5779]

I added a 12v actuated ball valve to the heater core line. Didn't really notice any colder ac temps but you can def feel the heater getting hotter and colder as you flip the switch from inside.

I think my next shot is going to be a fan on the condenser.

[MadScience]

Another update, I had a slow leak at all the connections to the valve.

I think the issue was just that my hoses were old enough to deteriorate a little from the inside. Changing the screw type hose clamps to constant pressure spring type ones didn't fix it. Neither did replacing the valve itself. Replacing the hoses did fix it.

When I installed the new hoses, I wanted to be able to just delete this mod in case it turned out to be bogus. So I figured out that I could just add some short straight hose sections as stubs to the heater core and attach the valve without cutting the pre-formed hoses at all.

So my issue was either old hose, or making the connection at a point where the hoses had a slightly different diameter. However looking at the hose, my money is on the hose deteriorating.

[arctictraveller]

Originally Posted by MadScience

Another update, I had a slow leak at all the connections to the valve..

Leaks aside, I haven't re-read the entire thread, but did you simply block the coolant flow or install a bypass? I'm still interested in knowing if there are any issues with blocking the return flow by using a simple on / off valve.