Heater wiring

by JF74chevelle Thu Mar 08, 2018 7:30 pm

Hey guys, I pulled the ac box off the fire wall and installed an ac delete box to keep my heater. With the new engine I don’t have the plug at the back of the head for the thermal switch I believe it’s called. It has two yellow wires connected to it. Is that okay?

Also do I need any vacuum lines for the heater or can I move them and plug them?
I took out the heater control valve because it interfered with my Holley fuel line.

by 73ss Thu Mar 08, 2018 7:38 pm

It's ok to leave it un-hooked. Those wires are for your low speed only on the fan. You will still have the other 3 speeds. If you twist them together, Your low speed will be on all the time. When the engine came up to temp, The low speed on the fan would turn on. Weird set-up.
You should be fine with no vacuum lines, although it may blow some heat all the time without the heater valve. Maybe it won't with the delete box set-up.

by JF74chevelle Thu Mar 08, 2018 8:30 pm

73ss wrote:It's ok to leave it un-hooked. Those wires are for your low speed only on the fan. You will still have the other 3 speeds. If you twist them together, Your low speed will be on all the time. When the engine came up to temp, The low speed on the fan would turn on. Weird set-up.
You should be fine with no vacuum lines, although it may blow some heat all the time without the heater valve. Maybe it won't with the delete box set-up.

Thank you so much for the help! I’ve been thinking I was right but I needed to hear some outside advice.

by 73ss Thu Mar 08, 2018 9:24 pm

You are welcome.

On second thought, you may need the vacuum lines to switch from dash-vents to defrost, etc. I don't have experience with the delete boxes, but the flap doors for the vents and defrost are vacuum operated. Non A/C cars are cable operated.

by JF74chevelle Thu Mar 08, 2018 9:27 pm

73ss wrote:You are welcome.

On second thought, you may need the vacuum lines to switch from dash-vents to defrost, etc. I don't have experience with the delete boxes, but the flap doors for the vents and defrost are vacuum operated. Non A/C cars are cable operated.

I guess we’ll have to give it a try to find out

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