What exactly is entailed to convert from DA6 to V5 compressor?

I need to upgrade to 134a and need to replace the compressor also. Thought I might as well go to the superior V5 compressor while I was at it.

It's hot as hell in central Florida and one working window is just not cutting it.

Thanks,
Dehydrated in FL

I did the V5 & R134a conversion in my Fiero several years ago. It was a fair amount of work. Here's a brief list of what's involved:

1) Modify compressor mounts to fit the V5
2) Swap V-belt pulley onto V5 compressor (requires a special tool)
3) Replace receiver/dryer unit and orifice tube with R134a compatible parts
4) Replace all the seals in the A/C system with R134a compatible seals
5) Modify engine wiring harness to accommodate the V5 compressor
6) Have custom compressor hoses made to fit the V5 compressor

On the DA6/HR6 compressor, you have 3 separate switches controlling the system: a low pressure cycling switch on the receiver/dryer, a high pressure cut-off switch on the compressor, and a fan switch on the compressor.

On the V5 setup, there are two switches (high and low pressure). Both switches are on the compressor. So the wiring for the cycling switch needs to be re-routed back to the compressor. And both switches on the V5 get wired into the cycling switch circuit.

Also, the V5 compressor doesn't have a fan switch, because it was used in cars with ECM controlled radiator fans. The V6 ECM can't control the radiator fan. So you have to rig something up. I used the low-pressure switch to double as the fan switch; it activated a relay which would ground the fan switch wire.

The high pressure cut-off switch on the DA6/HR6 compressor is wired into the ground leg of the compressor clutch. The V5 compressor doesn't do that (the high-pressure cutoff is part of the cycling switch circuit). The cut-off switch wiring needs to be deleted, so the clutch is grounded at all times.

Also, the suction and discharge ports on the V5 compressor are opposite from the DA6/HR6 compressor. And the compressor itself is a different size/shape, with the ports in a different location. So custom compressor hoses need to be made, to account for that. Neither the stock V6 nor 4cyl compressor hose assemblies will fit, due to interference issues.

Sounds like fun, doesn't it?

[This message has been edited by Blacktree (edited 07-08-2014).]

Didn't some years of 4 cyl Fiero's have the V5 compressor? Wouldn't it be possible to obtain hoses from years that had it?

I asked my local shop if I bring in cans of R12 will they charge my system. It's cool but not cold. He said they would but He suggested I just convert it said it amounts to vacuuming out the old, replacing seals, he didn't mention the dryer and orifice but I did (those two items aren't a big cost) he seemed to think it would be fairly simple to do. he does know I've got a 3800SC motor in it, but quite frankly since I didn't do the swap I'm not sure which compressor is under there. anyway I'm just going to use the R12 this time since I already have the cans and get a quote from a couple people how much to switch. need to get under there one of these days to check which compressor was used.

quote Originally posted by da.slyboy: Didn't some years of 4 cyl Fiero's have the V5 compressor? Wouldn't it be possible to obtain hoses from years that had it?

The '87-88 4cyl Fiero has the V5 compressor. I tried those hoses, and still had interference issues.

I have an 86 SE Fiero (with HR6 compressor), and an 88 coupe Fiero (with V5 compressor). I have converted both to R134a, and both cool very well. I see no advantage in changing your HR6 system to the V5 compressor. The HR6 system needs a cycle switch change to work with R134a, and the V5 needs a control valve change to work with R134a. After these parts are changed, either system can handle R134a just fine.

quote Originally posted by Blacktree: I did the V5 & R134a conversion in my Fiero several years ago. It was a fair amount of work. Here's a brief list of what's involved: 1) Modify compressor mounts to fit the V5 2) Swap V-belt pulley onto V5 compressor (requires a special tool) 3) Replace receiver/dryer unit and orifice tube with R134a compatible parts 4) Replace all the seals in the A/C system with R134a compatible seals 5) Modify engine wiring harness to accommodate the V5 compressor 6) Have custom compressor hoses made to fit the V5 compressor On the DA6/HR6 compressor, you have 3 separate switches controlling the system: a low pressure cycling switch on the receiver/dryer, a high pressure cut-off switch on the compressor, and a fan switch on the compressor. On the V5 setup, there are two switches (high and low pressure). Both switches are on the compressor. So the wiring for the cycling switch needs to be re-routed back to the compressor. And both switches on the V5 get wired into the cycling switch circuit. Also, the V5 compressor doesn't have a fan switch, because it was used in cars with ECM controlled radiator fans. The V6 ECM can't control the radiator fan. So you have to rig something up. I used the low-pressure switch to double as the fan switch; it activated a relay which would ground the fan switch wire. The high pressure cut-off switch on the DA6/HR6 compressor is wired into the ground leg of the compressor clutch. The V5 compressor doesn't do that (the high-pressure cutoff is part of the cycling switch circuit). The cut-off switch wiring needs to be deleted, so the clutch is grounded at all times. Also, the suction and discharge ports on the V5 compressor are opposite from the DA6/HR6 compressor. And the compressor itself is a different size/shape, with the ports in a different location. So custom compressor hoses need to be made, to account for that. Neither the stock V6 nor 4cyl compressor hose assemblies will fit, due to interference issues. Sounds like fun, doesn't it?

Blacktree, this is a 10 year old post that I'm responding to, but I wanted to ask a couple of questions here about your swap...


My daughter has a 1985 Fiero 2m4 SE, which we've upgraded and installed a V5 compressor, which was actually used on 1986-1988 4cyl Fieros (not just 87-88). From your list...


1) Modify compressor mounts to fit the V5: ... I used the factory 1987-1988 Fiero A/C brackets (I converted to serpentine)

2) Swap V-belt pulley onto V5 compressor (requires a special tool): ... didn't need to do this because I converted to serpentine

3) Replace receiver/dryer unit and orifice tube with R134a compatible parts: ... this should be easy, nothing different than any other Fiero R134a conversion.

4) Replace all the seals in the A/C system with R134a compatible seals: ... same as above.

5) Modify engine wiring harness to accommodate the V5 compressor: ... this is where I have my questions.

6) Have custom compressor hoses made to fit the V5 compressor: ... 1987 Fiero AC lines will fit since I'm going Duke to Duke...


You said...


"On the V5 setup, there are two switches (high and low pressure). Both switches are on the compressor. So the wiring for the cycling switch needs to be re-routed back to the compressor. And both switches on the V5 get wired into the cycling switch circuit."

If the low pressure switch is already on the Accumulator in the front compartment of the car, why can't I just keep it there? Is there a reason why it needs to be moved to the back?


"Also, the V5 compressor doesn't have a fan switch, because it was used in cars with ECM controlled radiator fans. The V6 ECM can't control the radiator fan. So you have to rig something up. I used the low-pressure switch to double as the fan switch; it activated a relay which would ground the fan switch wire. The high pressure cut-off switch on the DA6/HR6 compressor is wired into the ground leg of the compressor clutch. The V5 compressor doesn't do that (the high-pressure cutoff is part of the cycling switch circuit). The cut-off switch wiring needs to be deleted, so the clutch is grounded at all times."

On the V5 Compressor, why can't I simply install a new high pressure switch where the high pressure switch goes, and then install a fan switch where the low pressure switch would normally go on the V5?


Thanks! I appreciate it!!!


EDIT: I also wanted to ask generally, whether or not the sensors / switches (when installed in the compressor) can ground out properly, or if I absolutely need to use the 2-lead connectors? I managed to source several original high pressure (red) and low pressure switch (white / mushroom) sensors that were all brand new, so I bought them. And now I realize... the V5 compressor is aluminum... so, this poses a problem, does it not?

[This message has been edited by 82-T/A [At Work] (edited 08-31-2024).]