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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
1983 Firebird, there are two wire connectors attached to the firewall next to the blower motor, not connected.
FIrst pic is mine. Second is one I found online with the boxes there. What are they?
Your 1st pic shows a harness for AC but a non-AC blower box. The one red wire is for the high speed of the blower motor; the one with the greens in it is for the compressor. No idea why those 2 things (non-AC box and AC harness) are both present in your car although if I was the guessing kind I'd guess your car had AC originally and someone "improved" it by hacking it out.
The other pic, with the blue/green connector, is a baro sensor for a computer-controlled carb system. Since "vacuum" is the DIFFERENCE BETWEEN the pressure INSIDE the manifold and the pressure OUTSIDE of it, you need BOTH measurements to accurately determine it. The MAP sensor (Manifold Absolute Pressure) measures the pressure INSIDE the manifold. In the earlier years of these cars they didn't have the refinement of reading the barometric pressure (pressure in the ambient), but just sort of "assumed" that it was near sea level pressure, which of course leads to problems if the car is at high altitude or on Mars or something. Starting in around 84 or so they added the baro sensor to fine-tune that in some applications. I don't see that wiring in your car.
So it's an original Canadian car, so it delivered with no A/C. Seems like they would have tucked the connectors away somewhere from the factory.
Could be where a MAP sensor would be. Also since it's a Canadian spec, it's got a non-CCC quadrajet, so Im guessing a MAP sensor wouldn't be necessary. But also you would think they would have tucked the connectors away from the factory, if a MAP was never installed.
Last edited by MentalEntropy; Sep 3, 2022 at 11:31 PM.
The baro sensor connection for cars equipped with that, is included in the computer-controlled-carb harness. The ENTIRE CCC harness comes through the windshield cowl at the bottom of the pass side kick panel, through the area behind the inner fender well where the power antenna motor also lives in cars equipped with that, and out from between the fender and pass side wheel well. A car without the CCC system ENTIRELY lacks that harness. So it's not "tucked away"; it simply was never installed in the first place, if in fact the car was an export model.
The MAP sensor looks almost the same as a baro sensor, and its wiring is also part of the CCC harness. It would have been right next to the brake booster on the driver's side.
Although, the whole Canadian thing still doesn't explain why that car has AC wiring but a non-AC blower box. The factory did a very similar thing with the AC harness: it was ENTIRELY separate from ALL the other harnesses in the vehicle, and was installed along with whatever HVAC system the car was equipped with. It comes through the firewall in a big rubber grommet right below the heater hose connections. On the firewall side, it goes to the blower circuitry (resistors, high-speed relay and Big Red Wire battery feed) and compressor, and also contains the little plastic vacuum lines for the "supply" from the engine and the heater control valve if equipped. On the cabin side, it plugs into the AC control head, and has a connector that plugs into the dash harness, for a single power wire that powers the whole thing. A non-AC car would therefore not come with AC wiring: they would have put in the appropriate harness for the system they installed, which is quite different from an AC one. The blower resistors are in a totally different place for example. You have the non-AC blower resistor wiring but the AC compressor wiring. Something in there isn't original.
The firewall itself was also different between AC and non-AC cars but I don't know the details except that the big hole for the air to flow through is different. I couldn't tell you which version you have. Most of the part that's different is hidden behind either the evap housing or the blower box thing that you have.
Great info.
Its definitely a Canadian car, the guy I bought it from imported it from Montreal, gave me all the paperwork, pretty neat. Has all the original metric gauges installed. Also has the non CCC quadrajet, which I read was how they were usually spec'd; the CCC was a buy up option. US cars had to have the CCC for emissions restrictions. Also definitely a non a/c car. Has the non a/c controls and vents blocked in the cabin with factory block off plates.
There is definitely no CCC harness like you described. Nothing coming through at the pass kick except the antenna feed.
The blower harness is just a small harness with a few wires, and these weird connections don't come through there. They go back and meet up with the main harness behind the distributor.
You might find that the car will smell less like engine and otherwise act better, maybe have less mystery heat coming in under the dash for example, if you put that rubber grommet back into its hole properly.
Still in all, you definitely have some AC wiring there. Might be more history to all that than what you've been told. What you have there is part of the main engine harness. No idea whether all that came installed in non-AC cars but I seriously doubt it.
Yea I see that grommit pushed in now . Funny what a new set of eyes will notice that you looked right past. On a Mustang forum, I posted a pic of my engine compartment for an unrelated issue, and a guy was like, here's the answer to your question, and by the way, you have a small leak on the left valve cover, front side bottom. And I sure did have a leak that I hadn't noticed.
Anyway, guess I'm back to it maybe being a baro sensor? I need to check that red wire, if it's for A/C, looks like it should have power all the time.
Interesting though, lots to uncover with this thing. Definitely love it.
Back to what being a baro sensor? You don't have one.
You are correct about the red wire, that's the battery feed to the blower high-speed relay in a car w AC. Not much to check about it; it doesn't do anything.
No; as repeatedly repeated, that harness if for AC. It's the compressor wiring. It's part of the engine harness. It would plug into the AC harness if your car had one, the one coming through the rubber grommet, which would be very different for an AC car. All those green wires you have there run along the inside of the driver's side valve cover and the other end of them would eventually go to the compressor you don't have. You can probably find at least one if you know where to look.
. Funny what a new set of eyes will notice that you looked right past. On a Mustang forum, I posted a pic of my engine compartment for an unrelated issue, and a guy was like, here's the answer to your question, and by the way, you have a small leak on the left valve cover, front side bottom. And I sure did have a leak that I hadn't noticed. 