94, 4.0L OHV HEATING SYSTEM "THERMAL VALVE"

[gaz]

Hello,

I am performing a complete engine/PCM/wire harness with all sensors/accessories, dash/column from a 94 California emissions Explorer to my 87 BII.

Looking over the lines/hoses to the heater core, I noticed what other manufacturers call a thermal valve, mid stream of the coolant lines to the heater core.

In the past, with other manufacturers, I have just done away with these devices when they fail. I desire to "do away with this one", during the installation and just use regular 1 piece lines/hoses without it.

Will deleting/omitting this component cause any computer codes or impede this 94 EFI PCM from allowing the highest possible fuel economy (excluding a greater amount of time to warm the engine up to temp)?

I do understand that may slow the engine warm up process a little and that in the winter, it will have an impact on the overall heating system. I'm alright with these effects.

 

[Eddo Rogue]

I don't think that affects the CEL or the sniffer test, so you should be fine.

 

[Uncle Gump]

Are you talking about the heater control valve?

 

[gaz]

UNCLE GUMP,

In the engine bay, both the supply and return hoses to the heater core are interrupted by a black plastic valve; I appologise for not looking up the correct nomenclature for the device.

 

[Uncle Gump]

It's all good...

But why on earth would you want to remove it? Will it increase MPG's?

 

[RobbieD]

Without looking in the manual, on a '94 I think the heater cutoff is only for blocking coolant through the heater core when the AC is turned on. Seems like it may have been added as part of the factory's conversion from R12 to R134a.

 

[snoranger]

It’s a bypass valve. It stops coolant flow to the heater core in the MAX A/C position and recirculates it.
Its not a problem if you want to eliminate it... just run new hoses and plug the vacuum hose.

 

[gaz]

@Uncle Gump , @RobbieD , @snoranger ,

This sounds great, the A/C will be disabled or not installed. This will be simpler and work great as I already have aluminum 1 piece heater core hoses.

Anyone happen to know the approximate length serpentine belt to use when I don't turn the a/c pulley (on 94 ohv 4.0l)?