Heater Control Valve Delete, Yes or No?

[SofaKing95]

Just finished replacing the 30 year old:

• thermostat
• radiator hoses
• heater hoses
• dash gauge sending unit
• and leaky heater control valve
• Prestone coolant flush and new coolant

on my 1995 XLT.

After everything was wrapped up I decided to do some checking of things using the infrared temp gun, just to confirm temps at various points as engine came up to temp and proper functioning of the system.

Got to thinking -- that heater control valve is a piece of junk and that part of the HVAC system is poorly designed IMO, almost like it was done as a senior high school engineering project over a weekend. So I've been thinking of just deleting it by substituting in a couple of pieces of 1/2" copper pipe and some hose clamps. My understanding is that the valve is there to prevent hot coolant going to the heater core when the heating system is OFF (i.e., bypass mode). In reality, the valve never fully closes, the position of the butterfly inside the valve is either PARTIALLY open or fully open, i.e., heat OFF / heat ON respectively.

I verified this with both the new and old valve by blowing into the various ports, plugging the open ports with my fingers while simultaneously opening and closing the valve via the vacuum plunger. I was also able to verify this partially open condition (when heat OFF) while on the vehicle using the temp gun and checking hose temps. The hoses that are shunted off (going to the heater core) by the valve when the heat is OFF run at a about a 15-20% lower than when the valve is open (heat ON). For me that doesn't really do it, and I'd prefer to have the peace of mind that a piece of plastic junk isn't going to leave me stranded one day.

Also note, many (most?) older GM models have flow to the heater core ON at all times, no valve -- but maybe the HVAC components in the dash are configured differently.

Thoughts?

 

[410Fortune]

I added one to my bronco ii
I use a zip tie to close it in the summertime and remove the zip tie in winter

 

[J_C]

Understandable why you want to do it, though I would want a little coolant always circulating through the core, so sludge builds up slower. A delete accomplishes that too. IDK how well the blend door seals, could be that your A/C doesn't blow as cold with full coolant flow.

 

[SofaKing95]

Understandable why you want to do it, though I would want a little coolant always circulating through the core, so sludge builds up slower. A delete accomplishes that too. IDK how well the blend door seals, could be that your A/C doesn't blow as cold with full coolant flow.

I'm thinking the A/C issue you mention was the original intention of the valve, although I'm not seeing enough of a differential. The sludge point is also a good observation.

I don't really use the A/C and the rig only get's driven 1,500 miles per year (lol)...definitely leaning towards deleting, that said, I may just wait so see if it ever springs a little leak like the OEM one did, after 30 years.

I may however at some point take it cross country, and if I do, I'll delete the valve for the trip and then maybe leave it that way afterwards.

 

[410Fortune]

They are cheap and easy to replace… only reason to delete it is if it’s problematic and not working imo and if that is the case then you have vacuum issues that go deeper then this valve

The 4 ports unit was replaced later with a two ports unit, less fail points only really need to block the intake to the heater core

Backflushing the heater core whenever you have the lines open is a great idea and a great way to avoid sediment and eventual failure

 

[DintDobbs]

I don't have any thing to contribute to this conversation other than what has already been said, but +1 to both 410Fortune and J_C.

Also, what you said, if it took 30 years to kill it once, it's going to take another 30 years to kill it again. I'd say replace it and roll with it.

 

[C420sailor]

It is to improve air conditioning efficiency. Air through the evaporator and the heater core follow the same path, so a hot heater core is going to push your AC temps up.

I believe it goes evaporator then heater core, so it shouldn’t affect the pressures in the AC system.

That said, if you’re gonna delete, I would do what is recommended above, and have some form of valve.

 

[SofaKing95]

It is to improve air conditioning efficiency. Air through the evaporator and the heater core follow the same path, so a hot heater core is going to push your AC temps up.

I believe it goes evaporator then heater core, so it shouldn’t affect the pressures in the AC system.

That said, if you’re gonna delete, I would do what is recommended above, and have some form of valve.

Found this...the kind of construction (all brass) I'd prefer...something for me to think about, never knew such an animal existed.