mrbonzia

i have a 84 c4 can this be bypassed and still have heat

Chatman

If you mean the valve that determines whether hot coolant flows to the inside of the car and through the heater core, then you could bypass it. You would just have heat all the time. If you meant the heater core, because it is leaking, then the answer would be no. You can bypass it so that the hot coolant doesn't enter the inside of the car but then no, or little, heat.

mrbonzia

HEATER CORE IS FINE just very little heat was trying to see the options there are for the valve seems to be a hard item to find

GKK

Is this the part? http://www.ecklers.com/product.asp?p...0&dept_id=1193

You could also, fabricate a manual one using plumbing parts from the hardware store.

convas

Have you tried just pulling the vacuum line off it and see if the heater works better, without vacuum it should be fully open all the time.

JackDidley

You can splice a sifferent one into the hose from another car. The one on my 80 Vette also fits a Dodge truck.

AGENT 86

Here is a pic of mine, after removing the valve part. I have heat when I need it, and cold AC when I need it.
For what it's worth, GM eliminated the valve somehere around 1988.

mrbonzia

found the problem vacumm liones inside the car at the heater controls are bad

fat dawg

Need a little help concerning "heater control valve" I am confused.
Heater control valve or heater control valve for engne oil cooler system. Heater will not work and I am trying to figure out what I need. The latter has been discontinued and the former does not seem to be what I want.

HEEPPPPP

FAT DAWG

rodj

The oil cooler , if fitted has no control; sees full coolant flow all the time.
The heater control valve is on the engine side of the firewall where the hoses enter .Can be bypassed or replaced with non Vette one as mentioned

silfox

Without the heater control valve, it would seem you would have have hot coolant flowing through the heater at all times. How do you keep it from blowing hot air inside all the time. Guess what I'm saying is, I'm not sure exactly how the blend air doors inside the heater work so it would seem that even when you want AC, you would still have the hot coolant flowing into the system and screwing up things.

MikeC4

You answered your own question....sort off...The blend door will will block the heater core air when controls set to cold air and vice verse. The later C4's do not have a "conrol valve" and coolant is always flowing through the heater core...

Randy Ferraro

I read this thread about 2 years ago and it did not help me then. My 84 had a leaky heater control valve. Running heat all the time meant having lukewarm air conditioning, too much hot air in the cabin. So, with heat in an 84 it is all heat or nothing. Replacing the factory $130 valve was not in the budget, and no amount of bypassing solved the problem. I live in the desert where spring days can be 85 degrees and nights can be in the high 30s. I finally solved the problem with Four Seasons part #74800 Heater Control Valve. It costs about $30. It cleaned up the plumbing in the engine compartment quite a bit. The original design was a clusterf@#k. The Four Seasons part mounted right up by the heater core nicely and works exactly as the factory did. If ever I have to find this part number again for future repairs, then here it is.
Four Seasons part # 74800 Heater Control Valve

caddyboy84

You're right, in 88 they used an electric diverter door, which I don't like because it keeps hot ant-freeze comming in the car all the time. The valve vacumm line works with the control unit inside the car and opens the valve when the heat is turned on, there are replacement valves that are cheap ($20), the OEM's are expensive and are an elaborate set-up of metal tubes. I know people who have installed a simple ball-valve from the hardware store and just open it in the winter and close it in the summer. I was thinking of doing this, because in my car the A/C has to fight the hot anti-freeze inside the heatercore in the summer. I think a control valve was the better design. There are aftermarket valves that are cable controlled, almost like a ballvalve but you cortrol it from a lever inside the car, it eliminates the need for vacumm and bypasses the dash control for on & off.

raymos

I went this route today on my 1984 Vette. Had to purchase the valve and about 18" of rubber tubing to connect the lower heater core at the firewall to the port of the valve (smaller diameter). The 74800 valve has 4 ports but you only need 3 so you need to plug the other smaller diameter port with a cap and clamp, which you can purchase from an auto store. The large ports on the valve will connect to the existing tubing from the back of the block and the elbow that comes off the hard line in front of the valve.

Black LS2

Please post the pic...mine is OK..........for now. I am sure the day will come.

raymos

Pic added to my post. Enjoy

Elijah Collins

How did you hook it up sine the 4 seasons has 4 stems and the factory one only has 3

raymos

Use a plug like the one in the link below. I originally used a plug from a local parts store made of rubber and it was fine for several years but is now dry and cracking. Replaced with this one.

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