a/c help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rob'68 · 10-02-2003, 11:37 AM

The a/c in my truck is missing the condenser, accumulator, and the hoses that go to them have been cut. I'm not sure why. The heater hoses are still intact. The a/c wiring harness is melted, so it needs replaced. My question is this: can I install only the wiring harness now and use only the heater/defrost? And replace the other parts later for the a/c? I need the defost now in the early morning. Thanks.

*67Fleetsidedream* · 10-02-2003, 12:39 PM

The heater and A/C are two different systems. You can disconnect the A/C wiring harness and the heater will still work. You will just have to make sure that your blower is working and the hot and cold vent( under the hood next to the cowl ) is switched to the hot side. Make any sense?

Rob'68 · 10-02-2003, 11:39 PM

67Fleetsidedream, thanks for responding. You say that the heater will work without the a/c harness. Is there separate wiring for the blower? Could you go into more detail about the hot/cold vent? Thanks.

Hutch · 10-03-2003, 12:35 AM

Rob'68
Yes the heater will work without the a/c connected.
Both the a/c and the heater share the same blower.
The wiring for the blower is wired to the switch on the control panel.
There is a couple of devices to look out for:
One is a a vacumn controled heater cut off valve located on the inner passenger fender well.
This unit is controlled by a vacumn switch located on the top of the control panel and is activated by the top slide control.
The other is the high speed fan relay iy is located behind the glovebox under the dash near the top between the heater box and the cowl.
when you get the wireing worked out and your high speed does not work check this item

Another item is located inside the cab and is a flap that shifts the air between the floor and dash vents and is cable controlled from the dash.
These air diverter flaps are almost always broken.
Here is a vacumn diagram pic

Have fun

10-02-2003, 11:37 AM	#1
Rob'68 Registered User Join Date: Sep 2003 Location: Palmer (Dallas) Posts: 33	a/c help The a/c in my truck is missing the condenser, accumulator, and the hoses that go to them have been cut. I'm not sure why. The heater hoses are still intact. The a/c wiring harness is melted, so it needs replaced. My question is this: can I install only the wiring harness now and use only the heater/defrost? And replace the other parts later for the a/c? I need the defost now in the early morning. Thanks.

10-03-2003, 12:35 AM	#4
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	Rob'68 Yes the heater will work without the a/c connected. Both the a/c and the heater share the same blower. The wiring for the blower is wired to the switch on the control panel. There is a couple of devices to look out for: One is a a vacumn controled heater cut off valve located on the inner passenger fender well. This unit is controlled by a vacumn switch located on the top of the control panel and is activated by the top slide control. The other is the high speed fan relay iy is located behind the glovebox under the dash near the top between the heater box and the cowl. when you get the wireing worked out and your high speed does not work check this item Another item is located inside the cab and is a flap that shifts the air between the floor and dash vents and is cable controlled from the dash. These air diverter flaps are almost always broken. Here is a vacumn diagram pic Have fun Attached Images __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

10-02-2003, 12:39 PM	#2
67Fleetsidedream Wiseass secured himself a BAN Join Date: Nov 2000 Location: MOON!!! Posts: 2,282	The heater and A/C are two different systems. You can disconnect the A/C wiring harness and the heater will still work. You will just have to make sure that your blower is working and the hot and cold vent( under the hood next to the cowl ) is switched to the hot side. Make any sense?

10-02-2003, 11:39 PM	#3
Rob'68 Registered User Join Date: Sep 2003 Location: Palmer (Dallas) Posts: 33	67Fleetsidedream, thanks for responding. You say that the heater will work without the a/c harness. Is there separate wiring for the blower? Could you go into more detail about the hot/cold vent? Thanks.



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