1968 Water Control Valve and overheating

[TexAg]

Random question: I just started looking into the AC/heating system on my car and came across the water control valve. Interesting design concept, I must say. So here's the question. If this valve shuts off the coolant flow through the heater core when the AC is turned on to maximize air cooling, isn't it reasonable to think it might lead to over heating? It seems that when external temps are the highest is when one would run the AC. So, high external temps and no coolant flow through the radiator and/or engine block would seem to be a disaster in the making.

I haven't had a problem, but I don't usually run the AC either. And, it's not like I don't trust the fine engineers at FOMOCO, but still. Am I over thinking it? Inquiring minds want to know.

 

[robert campbell]

I recored radiators way back in the late 60's at a local radiator shop. Worked on a ton of 60's cars. You have hit on the reason that air conditioned cars have upgraded cooling capacity. Larger radiators, fan shrouds, and better fans. All due to the conclusion you came to.

So if you have a dirty system or other cooling problems, turning on the A/C may push you over the edge. But if your cooling system is in good shape it will not.

It is always a good idea to put your car in neutral on hot days at traffic lights. This lets the idle pick up a bit to move more air and also releases the torque convertor and generating less heat in the tranny. Also, it is why some people turn their A/C's off in traffic even if it is uncomfortable for a bit.

And in the NW..... what is air conditioning???

Rob

 

[dalorzo_f]

high external temps and no coolant flow through the radiator and/or engine block would seem to be a disaster in the making.

The heater block valve only stops flow thru the heater core. It allows the AC to cool the water in the core, not fight constant flow of 200+ degree water as always runs thru the non-AC heater core.

With AC on and the valve in the no-flow mode there is still circulation thru the block and radiator.

The added cooling is to compensate for the extra load on the engine (= more heat ) to run the compressor and to overcome the unfortunate fact the AC condenser is always put right in front of the radiator, so a lot of the heat transferred from the AC gas goes right into the airstream that is hitting your radiator... higher inlet air temp = less cooling capacity.

 

[robert campbell]

+1. The valve just stops the water from going through the heater core. All else is still functioning as designed.

Rob

 

[TexAg]

Ah, that's right. I was over thinking it. Of course there is still flow throught the block and the radiator. Duh?? That would be what the big hoses at the top and bottom of the radiator are for.. Thanks guys! Feeling a little embarassed about now.