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| Thoroughly confused about adding AC to a 3800sc engine (Page 2/4) |
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dcarrd
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SEP 24, 11:20 PM
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Darth Fiero
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SEP 25, 01:50 AM
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| quote | Originally posted by Lou6t4gto:
What I gathered is that the Fiero compressor wont run at full capacity? Better off with the 3800 compressor but will have to get modified lines?
WHY would a Fiero Compressor Not Run at Capacity IN A FIERO ??? I'm using a 86 Fiero Compressor (with a 3800 Pulley and clutch) |
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If you already have a good working stock Fiero A/C compressor, the tools and parts necessary to switch out the V-belt pulley for the correct 6-rib serpentine unit, and the necessary bracket(s) to bolt it to a 3800 engine; then I suppose you could use it in a 3800 swap. But how many people have a good working / non-leaking stock Fiero A/C compressor??? How many people have the correct pulley to install onto it + the tools and know-how to do that? And what brackets do you need? You do realize you need more than one bracket, right? (The front and the rear of the compressor both need to be supported and bolted to the engine block.)
But even with all of the above, you'll still need the 3-wire A/C pressure sensor if you want the 3800 PCM to control the A/C clutch operation.
I'd venture to guess most people who are ready to do a 3800 swap, or any swap using a different than 2.8/3.4 iron-head pushrod engine, probably are in need of a new A/C compressor anyway. I have to question why one would go thru all the hassle of switching pulleys and making brackets and such to be stuck with an older design A/C compressor when there are better ones out there (like what came stock on the 3800).
Aren't there a few members on this forum still making 3800 A/C conversion lines?[This message has been edited by Darth Fiero (edited 09-25-2014).]
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Darth Fiero
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SEP 25, 01:53 AM
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| quote | Originally posted by dcarrd:
will this work to connect the pressure switch?
Hose fitting |
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Yes, if you get the 3-wire A/C pressure sensor from an R-12 car (such as a ~1990-93 W-body with a 3.1L V6).
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dcarrd
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SEP 25, 01:33 PM
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I picked up a used 3800 compressor from the mall to try out. At $30 shipped I figured Id take a chance considering they are $300 + new. Its a Delphi 5145 (part #1135145) and both ports are the same size. I believe it came out of the same model car as the engine, a 2000 GTP
. It has a connector near the pulley with two cut wires. I assume thats power? So if Im understanding right, I need to get the ac lines for this compressor and splice them with the FIero ac lines and add the fitting in the high side hose? Attaching the pressure sensor and wiring it as you explained above...Thanks for all the help
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Darth Fiero
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SEP 25, 03:17 PM
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| quote | Originally posted by dcarrd:
I picked up a used 3800 compressor from the mall to try out. At $30 shipped I figured Id take a chance considering they are $300 + new. Its a Delphi 5145 (part #1135145) and both ports are the same size. I believe it came out of the same model car as the engine, a 2000 GTP
. It has a connector near the pulley with two cut wires. I assume thats power? |
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A "new" ToughOne A/C compressor with lifetime warranty is available from Advance for $231 + $10 core. With any number of online discount codes, you should be able to get it for LESS THAN $200. Keep this in mind in case the used one you got has an issue (most likely = leaks).
The connector near the pulley is the power connection for the clutch. Should have dark green and black wires. Black connects to ground. Green connects to your A/C clutch relay. A diode must connect these two wires together (see original Fiero A/C compressor connector harness - you can use the diode from that for this). The silver band on the diode needs to face the green wire. Make sure you solder connections then dip the exposed connections in liquid electrical tape to seal out the water to prevent corrosion.
The factory 3800 harness would have had a diode already located in the compressor clutch wiring in what looked like a small white plastic box both the green and black wires ran thru. This diode is essential for prolonging electrical circuit life because it gives the voltage spike induced by a disengaging electromagnetic clutch a place to go. It will still work if you don't hook it up, but you could have issues in the long-term.
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So if Im understanding right, I need to get the ac lines for this compressor and splice them with the FIero ac lines and add the fitting in the high side hose? Attaching the pressure sensor and wiring it as you explained above...Thanks for all the help |
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Yes, you will need custom A/C lines made so you can connect the 3800 compressor to the Fiero's A/C lines that attach to the underbody. Make sure whoever you get the lines from installs a fitting in the smaller of the two lines (which is the discharge from the compressor) so you have a place to install the 3-wire sensor you need.[This message has been edited by Darth Fiero (edited 09-25-2014).]
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dcarrd
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SEP 25, 04:12 PM
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unfortunately the PO either removed the AC portion of the 3800 harness or it was not purchased with it. The AC relay is still in the engine bay so I can wire from there but I will have to find the diode and rewire from the ECU also.
I was planning on making the hoses myself since my mechanic buddy has the crimping tool and I have a Goodyear hose dealer real close. I have the Fiero end of the AC lines, just need to find the correct 3800 lines for the comrpessor.
Lastly, does the collector remain the same or do I just need to change the orifice tube to a larger one for the R-134a?
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dcarrd
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SEP 25, 05:34 PM
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I dont see the AC instructions in your site but from what I gather:
1. Pin 22 in the ECU gets wired to the D connector on C203 going to the AC Request
2. Pin 27 gets connected to the pressure sensor (which wire on the sensor?)
3. Pin 34 connects to the sensor (which wire and what is "5 volt reference" for?
4. Pin 35 to sensor ground (im assuming the wire is black.......does anything get hooked up to the manual transmission?)
5. since I dont have any ac relay wiring to use I would have to run a wire from pin 39 to pin C on the AC relay?
6. Pin B on the AC Relay to positive wire on compressor.
7. Pin A on AC Relay used to go to the AC Request on the C203 harness?(Not used anymore?)
8. Where the hell does Pin D on the AC relay go? lol
9. Ground on the Compressor gets attached to a good known ground on the block or chassis?[This message has been edited by dcarrd (edited 09-25-2014).]
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Darth Fiero
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SEP 29, 04:50 PM
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| quote | Originally posted by dcarrd:
I dont see the AC instructions in your site but from what I gather:
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My wiring instructions DO indeed give pin connection instructions.
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1. Pin 22 in the ECU gets wired to the D connector on C203 going to the AC Request |
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Pin C2-22. There are two PCM connectors, Blue is C1 and Clear is C2.
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2. Pin 27 gets connected to the pressure sensor (which wire on the sensor?) |
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My instructions say pin C2-27 connects to pin C of the A/C pressure sensor.
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3. Pin 34 connects to the sensor (which wire and what is "5 volt reference" for? |
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My instructions say pin C2-34 connects to pin B of the A/C pressure sensor. This is a 5-volt reference circuit the PCM supplies to the sensor so it can work.
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4. Pin 35 to sensor ground (im assuming the wire is black.......does anything get hooked up to the manual transmission?) |
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My instructions say pin C2-35 connects to pin A of the A/C pressure sensor. This is a ground reference circuit the PCM supplies to the sensor so it can work. If you are doing a manual trans swap, then this wire does not connect to the transmission at all, only the A/C pressure sensor.
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5. since I dont have any ac relay wiring to use I would have to run a wire from pin 39 to pin C on the AC relay?
6. Pin B on the AC Relay to positive wire on compressor. |
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It is going to be easier if you find a stock Fiero A/C clutch relay so the wire colors and pin location ID's match up with my wiring instructions. Otherwise, you are going to have to figure out how to use a different relay to wire everything up.
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7. Pin A on AC Relay used to go to the AC Request on the C203 harness?(Not used anymore?) |
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Yes it is still used and would remain hooked up to the C203 connector as it was stock since my instructions don't tell you to change anything relating to this wiring circuit.
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8. Where the hell does Pin D on the AC relay go? lol |
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Pin D is not used in the stock harness, nor will it be used in your conversion. Pin E of the A/C relay gets connected to C203 pin N (should be a black wire), as it would stock.
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9. Ground on the Compressor gets attached to a good known ground on the block or chassis? |
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Engine block ground.
Since you say you don't have the stock Fiero A/C clutch relay to work with, this is probably why you are getting confused on where things get hooked up. I wrote the wiring instruction sheets assuming you still had and were reusing the stock Fiero wiring bits (for the A/C clutch and such) in your swap.
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dcarrd
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SEP 29, 08:02 PM
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I DO have the AC Clutch relay, what I dont have is any wiring attached.
As far as the instructions, I couldnt find them, Im sure you have the wiring details there. Can you point me to them on your site?
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dcarrd
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SEP 29, 08:04 PM
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