Heater core bypass, stupid?

[454cid]

I've been meaning to install a valve, but haven't since I drive the truck so little. It'll definitely be easier on the HVAC system, since 200 degree coolant will no longer be flowing through the area being cooled. That's physics, there's no going around that. Not installing a valve is a cost cutting measure by GM. The Suburban gets it because it's such a large volume to cool.

GM would use a bypass, but I will simply dead head it. I do have a big block, so coolant flow may be different.

 

[GoToGuy]

The air that's being cooled is either outside air or recirculating air.

 

[454cid]

The air that's being cooled is either outside air or recirculating air.

The coolant is bringing in heat from the engine. It warms the box the air is moving through.

 

[L31MaxExpress]

Heater shut-off valve has helped every vehicle I have installed one on including a Ram that was all of a year old when I installed it. On a SBC or 8100 atleast, the engine actually runs cooler with the heater circuit flow shut off as you are no longer providing a bypass for coolant to flow around the radiator.

 

[Erik the Awful]

What I've read on other forums, for different vehicles, is that bypassing seals off the heater core which could cause a vacuum in the heater core as the fluid trapped in it cools. This could cause leaks, or so I've read

Only if you block off both hoses.

This is why isolation valves go on the return leg, so when you isolate it it blocks the core full of coolant

If you block off the feed leg, the return leg will still be under pressure from the rest of the cooling system and full of coolant.

 

[Menissalt]

This thread reminded me that my heater core is clogged so I need to bypass it until I decided to replace it

 

[454cid]

This thread reminded me that my heater core is clogged so I need to bypass it until I decided to replace it

I have a 5/8" to 3/4" fitting from NAPA that allows me to do that if I need to. I bought it when my heater core started leaking while out of town years ago.

 

[95burban]

I used a brass pex valve on my old powerstroke, worked great! You could use a coolant bypass from a ferd explorer to bypass the heater core. That correct @L31MaxExpress ?

 

[rob249]

Do you have the aux fan mounted in front of condenser? GM added the aux fan in front of condenser to add airflow at low, no speeds, to improve AC performance.
Your idea of adding shutoff valves is really a " feel good " idea. Before you tear apart the heater lines. Are you aware that GM already utilized this idea in certain model Tahoe's and Suburbans ? It reduces water through heater when AC cooling is in demand . A better idea.
Isolation of return leg? It's not just a water pump. It's a closed pressurized cooling system, not quite the same. But as always you free to whatever you want.

I will be adding two pusher fans in front of the condenser, once I get some more idle amps from the ad244. I am aware that GM used a valve on later trucks, not sure how that system works though. Does it shut off flow or bypass? Where does it bypass too?

If it bypasses from the inlet hose to the return, it would need two shut off valves, which would seal off the heater core.

For my ford, there is a simple shutoff valve mod that runs off of vacuum from the max AC/recirculate, different engine and HVAC system though. My Yukon is an all electrically operated HVAC system, don't know how the later ones are.

 

[rob249]

I used a brass pex valve on my old powerstroke, worked great!

Exactly what I'm doing this weekend, along with an entire AC rebuild. Original AC still on my 96' F350