88 Fiero GT AC compressor (Page 1/2)
Duck 1 FEB 24, 07:15 PM
install AC compressor and all fittings on rear of AC compressor
cyrus88 FEB 24, 07:28 PM
Ok, we'll get right on it. ๐Ÿคจ๐Ÿ˜

[This message has been edited by cyrus88 (edited 02-24-2023).]

RWDPLZ FEB 24, 08:08 PM
wut
Duck 1 FEB 25, 08:37 AM
My question was not intended to be a joke. The compressor on my 88 appears to have only 2 openings on the rear. These 2 openings are for the Freon connections , however, there is nothing for the fan and high pressure fittings on mine. I was trying to determine if there had been some type modification done to the one on my car. The engine coolant sensor wire ( green with white stripe) was twisted around another black or dark brown wire under the car and both had been wrapped around a compressor mounting bolt . With both wires attached to the bolt it caused the radiator fan to come on immediately when key was turned on. When I removed the 2 wires the fan worked as it should when I put the AC control switch to the on or max position. Here is the issue. my coolant sensor wire is now not attached to anything. This is why I was asking for information about what was normally hooked up to the back of a AC compressor. I guess what I really need is to find out where to attach the green with white stripe wire so my temp gauge will work. If anyone has any technical information I would appreciate it . ( P.S. I do not need anymore sarcastic answers )
fierofool FEB 25, 09:35 AM
The temperature gauge sending unit is in the corner of the head near the ignition coil and is nowhere near the AC compressor. The AC has no effect on the coolant temperature sensor reading.
Duck 1 FEB 25, 11:06 AM
Thanks for the information, I guess I wasn't exactly clear when i said temp sensor. The temp sensor I am talking about is on the top right side of block and controls when fan comes on when you have the AC on. It has one green wire with a white stripe.
sanderson231 FEB 25, 11:41 AM
The 4 cylinder and V-6 use different compressors. From what you describe it sounds like you have a V-6 where someone has installed compressor without the two pressure switch ports. The 88 V-6 uses an HR6 compressor with the pressure switches. Not all HR6 compressors have the ports for the pressure switch. For example the Cadillac 4.9 uses an HR6 compressor without the pressure switches because there are other means to provide this functionality through the body control module.

The two switches on the V-6 Fiero A/C compressor are both high side pressure switches.

The first switch which would have a green.white wire going to it closes at 280 PSI. This causes the coolant fan relay to energize and causes the coolant fan to run. This is redundancy since placing the A/C control head in Max, Norm or B/L will also energize the relay causing the coolant fan to run. If the pressure switch is not there and the green white wire is grounded the coolant fan will run all the time. There is also a coolant temperature switch which is in parallel with the pressure switch (green white wire) that will cause the coolant fan to run (on at 235 'F and off at 225 'F). Leaving the green white wire at the A/C compressor disconnected should still allow the temperature switch to start and stop the fan. The temperature sensor for the instrument panel gauge and the temperature switch for the coolant temperature warning light are not associated in any way with the coolant fan. If the gauge isn't working there is another problem.

The pressure switch that should have a black wire going to it opens at 425 psi. This switch is in series with the A/C compressor clutch coil. The purpose is to shutdown the A/C compressor if the high side pressure reaches 425 psi. This is to prevent rupture of a hose. However there is also a pressure relief valve to prevent hose rupture but this dumps all the freon charge to atmosphere. Without the pressure switch present this wire has to be grounded to allow the A/C compressor to run. You give up some overpressure protection redundancy without the pressure switch being present

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

Duck 1 FEB 25, 12:40 PM
I have the old compressor out of the original engine and it is a Harrison model # 1131671 and it had 2 places on the back of the compressor to attach wires. Sadly I do not have the original engine harness that was on the old engine . The old engine still has the coolant sensor next to the thermostat housing that has the green wire with white stripe still attached to it. It was my understanding that was the sensor to send temp info to fan relay and cause fan to engage if coolant got too hot with AC turned on. From what I am understanding from your information, the AC compressor I now have does not require any wires to be attached to it, is that correct ?
cyrus88 FEB 25, 03:16 PM

quote
Originally posted by Duck 1:

My question was not intended to be a joke.



Lol! There was no question.


quote
Originally posted by Duck 1:

install AC compressor and all fittings on rear of AC compressor



That is not a question.
sanderson231 FEB 25, 04:20 PM

quote
Originally posted by Duck 1:

I have the old compressor out of the original engine and it is a Harrison model # 1131671 and it had 2 places on the back of the compressor to attach wires. Sadly I do not have the original engine harness that was on the old engine . The old engine still has the coolant sensor next to the thermostat housing that has the green wire with white stripe still attached to it. It was my understanding that was the sensor to send temp info to fan relay and cause fan to engage if coolant got too hot with AC turned on. From what I am understanding from your information, the AC compressor I now have does not require any wires to be attached to it, is that correct ?



On the Fiero OEM type compressor there are pressure switches (bought separately) that plug into ports in the back of the compressor. These have o-ring seals and are held in by circ clips. The wiring connections are on the switches. Some compressors that are exactly the same size as the Fiero compressor (e.g. the 4.9L Caddy compressor) do not have the ports to install the pressure switches because some applications do not require the switches. You have to ground the black wire at the compressor to allow the compressor to run if there is not a pressure switch to connect it to (the pressure switch is normally closed). My 4.9L swap does not have the pressure switches. You give up some over-pressure protection but in my opinion the risks are small.

The coolant temperature switch you are referring to starts and stops the coolant fan regardless of whether the A/C is on or off. On the V-6 Fiero this is the only thing that will start the coolant fan if the A/C is off. This should still function normally if you leave the green/white wire at the A/C compressor disconnected (tape it so it can't ground accidentally).

P.S. you may have a compressor that has the ports for the pressure switches. Because the compressor typically comes without the switches these ports my have plugs in them held in by circ clips.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

[This message has been edited by sanderson231 (edited 02-25-2023).]