Ok, so... I'm converting to a V5 compressor... to get rid of the HR6 compressor in my 1985 Fiero.
HOWEVER... I accidentally recycled my old HR6 compressor, without saving the compressor switches.
I know the V5 also has two switches in the back... can anyone tell me what switches I need to get for the V5, and... if the old HR6 switches will fit in there, AND... where I can get new HR6 sensors?
I know there's something else I need to do... but basically... I don't have any sensors for my compressor... ugh... and they don't seem to sell replacement original ones.
Ok, so... I'm converting to a V5 compressor... to get rid of the HR6 compressor in my 1985 Fiero.
HOWEVER... I accidentally recycled my old HR6 compressor, without saving the compressor switches.
I know the V5 also has two switches in the back... can anyone tell me what switches I need to get for the V5, and... if the old HR6 switches will fit in there, AND... where I can get new HR6 sensors?
I know there's something else I need to do... but basically... I don't have any sensors for my compressor... ugh... and they don't seem to sell replacement original ones.
I think rockauto has some still. maybe the fiero store? honestly though that was a bit of an oversight. I do have some r134a switches out of a 1995 gtp so see what compressor it uses since those are known good
I don't want to create a new thread, since I already created this one, and no point in creating MULTIPLE threads (which I've already done, but don't want to make it worse, and I'll update all the dumb threads I've created once I figure this out).
...
Long and short, this is for my daughter's Fiero. 1985 Fiero 2m4 SE. It had the DA6 compressor, and I was able to use all the brackets from a 1988 to get the V5 compressor to fit.
I was able to find a set of usable 1987 Fiero 4cyl Coupe A/C lines from The Fiero Farm (thank you!):
The pair on the left is the original from my daughter's 1985, which connects the factory body-lines to a DA6. The pair on the right is the new one from a 1987 Fiero Coupe (4cyl), which connects the factory body-lines to a V5 compressor.
Note, the biggest issue with the DA6 is that the pressure and return line holes are REVERSED. The 87 line set fixes this for me, as you'll see if you look carefully. It allows the V5 compressor to correctly mate to the factory line, which are unchanged at least from this 1985 2m4 SE, and the 1987 donor car that this came from. The mounts are the same.
Next challenge is actually mounting the 87 line to the compressor. I ordered a brand new V5 compressor from Four Seaons, which makes high quality compressors. The problem is that the mount on the compressor has changed slightly, and there's a "puzzle" of sorts using different gaskets and spares to properly seat the lines at the compressor junction. Four Seasons uses the "lowest common denominator" approach, and thus creates a bunch of different sized gaskets to allow their single design V5 to work with everything else.
This is effectively the chart that I found:
And best I can figure at this point, this is my combination that I need to use:
... which now brings me to the A/C switches.
Ok, I'm not a big fan of taking no for an answer, so I used Maltego (a hacking tool) to scour the internet for me looking for both the original RED and WHITE switches that were original on the Fiero. I ordered three original sets from different places... and this is what has arrived so far.
Now, I still need to figure out what switch goes where, but here's what I understand:
- The low-pressure switch is the "white mushroom" original switch. - The high-pressure switch is the "red pintle" style original switch.
Here's where I'm confused, and I'm not finding what I need.
WHAT SENSORS DO I NEED TO UPGRADE TO A V5 COMPRESSOR?
This is a quick diagram I made (based on what I've read about the V5 compressor in the 1986 Fiero Service Manual) on where the low and high side pressure switches go:
OK, NOW... from what I can gather... both of them are "pressure switches" and it doesn't really matter at all which sensor goes where, because the pressure is equal in both of those locations. So... point being, if you had a low pressure switch, it would be fine in there, same as a high pressure switch would.
SO... with that in mind, here are three questions that I can't seem to answer:
- Can I simply just install the original White Mushroom and Red Pintle switches into the V5 compressor and be done with it? - What do I do with the "cycle switch" that's in the front compartment? Does this even need to do anything at this point? - Biggest issue that just occured to me. Is the V5 compressor made of aluminum? Or is that steel? These are 1-lead sensors, and if they need a ground, and the compressor is aluminum, then it's not making a ground?
Would really appreciate any help guys... thank you!!!
SO... with that in mind, here are three questions that I can't seem to answer:
- Can I simply just install the original White Mushroom and Red Pintle switches into the V5 compressor and be done with it? - What do I do with the "cycle switch" that's in the front compartment? Does this even need to do anything at this point? - Biggest issue that just occured to me. Is the V5 compressor made of aluminum? Or is that steel? These are 1-lead sensors, and if they need a ground, and the compressor is aluminum, then it's not making a ground?
Would really appreciate any help guys... thank you!!!
Here's the problem:
The DA6/HR6 is active when the cycling switch in the front compartment turns it on, and turns off when the cycling switch turns it off (clutch engaged or clutch disengaged).
The V5 compressor is a variable displacement compressor that varies output based on the control valve in the compressor body. Clutch is on when computer signals it on.
The red and white switches (high pressure cut-out and fan switch) are safety devices, designed more to protect the car and its components than anything else. The red switch cuts off if pressure is too high, and the fan switch keeps the fan on as long as the AC is on and pressures are elevated, to keep air moving across the condenser if the normal fan switch fails.
The switches on the V5 compressor are high and low pressure cut offs: The high pressure switch switch cuts off if pressure is too high, and the low pressure switch cuts off if pressure is too low.
What you're building is a hybrid system, a variable compressor in what is otherwise the original 'clutch slapper' type system. In theory, the best way to get this to work would be to use a computer from an 86-88 4 cylinder Fiero that had a V5 compressor from the factory, but there are likely other wiring changes that need to be checked and accounted for if installing it in an older car.
By far the easiest solution is just to buy the HR6 compressor to put in the 85.
quote
- Can I simply just install the original White Mushroom and Red Pintle switches into the V5 compressor and be done with it? - What do I do with the "cycle switch" that's in the front compartment? Does this even need to do anything at this point? - Biggest issue that just occured to me. Is the V5 compressor made of aluminum? Or is that steel? These are 1-lead sensors, and if they need a ground, and the compressor is aluminum, then it's not making a ground?
-No, V5 compressor low pressure cut-off switch functions at far lower pressure than the DA6/HR6 fan switch (V5 compressor switch ON 30psi, OFF 29psi, DA6/HR6 compressor switch ON 250psi, OFF 160psi). Red switches serve the same function. -Would need to be bypassed somehow, variable displacement compressor doesn't use it. -Aluminum is metal, and conducts electricity just fine. DA6 and HR6 were also aluminum. If the rest of the grounds are good, it will function fine with 1 wire switches.
[This message has been edited by RWDPLZ (edited 09-07-2024).]
Originally posted by RWDPLZ: -No, V5 compressor low pressure cut-off switch functions at far lower pressure than the DA6/HR6 fan switch (V5 compressor switch ON 30psi, OFF 29psi, DA6/HR6 compressor switch ON 250psi, OFF 160psi). Red switches serve the same function. -Would need to be bypassed somehow, variable displacement compressor doesn't use it. -Aluminum is metal, and conducts electricity just fine. DA6 and HR6 were also aluminum. If the rest of the grounds are good, it will function fine with 1 wire switches.
Thank you RWDPLZ! I appreciate it. So, my thoughts here are:
- The DA6/HR6 use significantly lower pressure switches. And the LOW pressure switch, of course, is to ensure that the compressor doesn't continue to run if it's completely run out of freon (and oil... more specifically?) Or are you saying that the pressures are the same, and RED switch can STILL be used in this case... just that the low-pressure switch goes on / off at lower pressures?
- Based on what I think you're saying... if I'm not mistaken, I can literally just keep it looking stock (the cycle switch), and just permanently ground out (or disconnect) the harness?
- RGR, good to know, thank you! I forget that 1970s homes used aluminum wiring too. I guess I confused myself, knowing that it's not ferrous, that somehow it also wasn't conductive, lol.
EDIT: Just found an ECM for $27 shipped, that has the correct PROM (FAU2975) that I need for my car... which is an 86 Fiero 2m4 SE w/ 5-speed and V5 compressor. The ECM itself is identical to mine (same ECM number, 1226864), so all I'll need to do is swap out the PROM.
I have both an 85 manual and an 86 manual, so I'll compare the wiring diagrams and see what the difference really is. Thanks!
[This message has been edited by 82-T/A [At Work] (edited 09-08-2024).]
Something to note. It doesn't matter in which port the high and low pressure switches are installed. They both sense pressures from the same internal chamber.
Thank you RWDPLZ! I appreciate it. So, my thoughts here are:
- The DA6/HR6 use significantly lower pressure switches.
No, significantly higher pressure switches, in the compressor. The cycling switch turns the compressor off when it gets down to 25psi on R-12, or 21psi on R-134A.
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And the LOW pressure switch, of course, is to ensure that the compressor doesn't continue to run if it's completely run out of freon (and oil... more specifically?)
Out of refrigerant, or prevents the system from going into a vacuum and imploding. The refrigerant controls actually don't care how much oil is in the system.
quote
Or are you saying that the pressures are the same, and RED switch can STILL be used in this case... just that the low-pressure switch goes on / off at lower pressures?
The high pressure switches are the same between the DA6/HR6 and V5, and serve the same function, to turn the system off if over-pressurized.
quote
- Based on what I think you're saying... if I'm not mistaken, I can literally just keep it looking stock (the cycle switch), and just permanently ground out (or disconnect) the harness?
While you CAN run the A/C system without the switches, they are safety devices, and bypassing a safety device is NOT a good idea. Unless you're referring to the cycling switch on the accumulator, in which case you could keep it on the accumulator if you wanted to? It would need to be bypassed or disconnected to use the V5 compressor.
quote
Originally posted by fierofool: Something to note. It doesn't matter in which port the high and low pressure switches are installed. They both sense pressures from the same internal chamber.
True, the wiring is also long enough the connectors can reach either port.
[This message has been edited by RWDPLZ (edited 09-08-2024).]
Here's what I've done (and again, thank you so much for helping me with this).
- I installed the RED factory original style high-pressure switch, and will continue to use that. - I have disabled the cycling switch.
I now have two problems:
- How do I make sure the fan turns on in AC mode? ...since I cannot use the original (white mushroom style) low pressure switch. It seems like the fan gets turned on automatically by the control head when you turn it to Air Conditioning... but does NOT when you are using the defrost option (that I saw from another thread).
- What color LOW PRESSURE SWITCH should I install in the other port? And... can this also be used to control the fan?
Thank you so much!!!
I intend to update my other thread and include all this information.
- How do I make sure the fan turns on in AC mode? ...since I cannot use the original (white mushroom style) low pressure switch. It seems like the fan gets turned on automatically by the control head when you turn it to Air Conditioning... but does NOT when you are using the defrost option (that I saw from another thread).
Correct, the fan turns on in the NORMAL, MAX or B/L A/C modes. The switch on the DA6/HR6 compressor is actually redundant fail safe (if you were running the A/C on a hot day and pressures are high, and you suddenly switched the A/C off or into defrost mode, the fan would continue to run until system pressure got down to 160psi).
(couldn't find a newer diagram)
quote
- What color LOW PRESSURE SWITCH should I install in the other port? And... can this also be used to control the fan?
THAT I'm not sure, I've never worked on a V5 car, and the whole point of the threads 10 years ago was to actually document what wasn't out there already. The old switches were no longer available (through conventional means anyway, not including checking dusty old shelves for inventory long forgotten), so I never bothered trying to find the original part numbers. Switch color may not even be indicative of the switch properties, they might both be white. If anyone with a nice original 86-88 4 cylinder could check, that would be great.
The low pressure switch on the V5 systems does operate the fan indirectly, in the opposite way the DA6/HR6 system does: Normally its just a safety to turn the A/C off below 8PSI (the modern switch is 29psi, the closest currently available equivalent).
Although shown in the same location in the diagram, the V5 low and high pressure switches don't perform the same function as the DA6/HR6 cycling switch: Rather they use the same input pin on the ECM. The V5 system also uses the fan control pin on the ECM to CUT the fan if pressures are too low (if pressure is too low, you'd actually want to warm up the condenser to increase pressure).
In order to use the V5 compressor in the DA6/HR6 car, you'd want to cut the signal wire to the cycling switch, and run new wires from that ECM pin to the switches on the compressor, wired in the same way. Note the locations of the C100 and C203 main connectors in the diagram in relation to the switches.
Again, I'd just put an HR6 compressor in the car and be done with it, far simpler and cheaper solution.
[This message has been edited by RWDPLZ (edited 09-08-2024).]
Next challenge is actually mounting the 87 line to the compressor. I ordered a brand new V5 compressor from Four Seaons, which makes high quality compressors. The problem is that the mount on the compressor has changed slightly, and there's a "puzzle" of sorts using different gaskets and spares to properly seat the lines at the compressor junction. Four Seasons uses the "lowest common denominator" approach, and thus creates a bunch of different sized gaskets to allow their single design V5 to work with everything else.
This is effectively the chart that I found:
And best I can figure at this point, this is my combination that I need to use:
Also to address this point from earlier:
Assuming your hose assembly mating face looks like this:
You want to use the green and red washers, and nothing else, with the green washer in the deeper hole.
I don't know WHY they did this, the original o-ring design was much better and simpler, maybe some patent troll shenanigans?
