birdman_29

iTrader: (1)

Can some body enlighten me on what a HVAC wiring harness is? My thoughts are the wiring harness that runs along the fire wall under hood. Just curious, if anybody has pics to see would be also appreciated, thanks.

sofakingdom

iTrader: (1)

It's not rocket surgery, really...

The HVAC wiring harness is the one that hooks up all the HVAC parts.

Go to a car assembly plant sometime and watch cars being assembled. It's EYE-OPENING. Any plant, any kind of car will do; although if you have a choice, I'd recommend the Bowling Green GM plant. Because, if you're going to watch cars being put together, might as well be Vettes, eh? Never been to St Therese but that would be my 2nd choice (Camaro).

A given model car usually has a number of "climate control" options. Additionally, several cars might share functionally identical parts of that system (among many others). These 2 facts prompt mfrs to group this sort of thing in packages separate from the unique parts of the car, and separate from other similarly organized variable packages. (engines for example)

In the case of our cars, there were at least 2 HVAC options available for them in all years. One with AC, one without. Additionally there were many engines, and the AC options for these cars were very much the same as those for other cars in many ways.

The HVAC harness is therefore a stand-alone assembly installed by itself at the appropriate point as the car rolls down the assembly line, in accordance with the option specified for the vehicle; and may not be unique to the particular vehicle model. (ours might have been shared with Caprice and Malibu for example) The main one goes from the HVAC control head, through the firewall near the heater hoses, and then branches off from there; one branch goes toward the blower motor, the other goes to the compressor. The harness includes the vacuum line(s) for the particular system; vacuum supply, and for some cars, the control line to the heater control valve. It gets power from 2 places: a brown wire under the dash that is its main source, and a big red wire under the hood that's the source for the high blower motor speed. Then, since it's easier for the factory to include the part of the compressor wiring on the engine with the compressor, there's a plug that joins the 2. And of course the part that goes to the blower motor, goes to the resistors that control its speed, and to the high speed relay.

birdman_29

iTrader: (1)

I have the wiring harness from a 91 RS that somebody is wanting to buy, and says it should fit in a small box. Well the harness I have seems to be a bit bigger than a small box will have enough room for, so that is why I asked the question I asked. An no I have not watch a full car being assembled, sorry. And it is not rocket science, I get it thanks.

Pocket

iTrader: (24)

Its a small harness that goes through the firewall under the heater core lines. Should be about 3' long and easily fit into one of the USPS flat rate boxes if thats what you're getting at

birdman_29

iTrader: (1)

Yes it is, thank you Pocket