On the 84 Fiero Your "low" side connection was on the A/C drier up front.
The "hi" side connector was on the A/C line from the compressor in the engine bay near driver's side decklid hinge.
That's a real nuisance connecting lines to an A/C gauge set.

It appears AC Delco made a retrofit kit to provide a connection up front on the tube upstream of the orifice valve.
You clamp it on and use a tool provided to pierce the aluminum tube, then install the Schrader valve.
I saw this part on RockAuto listed under A/C parts for 84 Fiero...



This is the comparison the the 84 (left) and later year A/C lines from condenser to evaporator.
The line from the condenser up front to the evaporator are interchangeable.
https://www.fiero.nl/forum/...160323-2-123621.html

[This message has been edited by fierosound (edited 09-20-2023).]

quote Originally posted by 88TTops: So I have rebuilt my ac, I am having massive problems with crushing the schrader valve on the low pressure side. I have all 3 parts available for the quick connect. They all keep crushing when the manifold quick connect goes in. So could I take out the schrader in the accumulator and just use the valve in the quick connect? I have been through 4 and keep having the same problem.

When you install the new low side adapter fitting on the accumulator, you first remove the schrader valve from the accumulator. The adapter has its own schrader valve. The adapter is a one-time use and seals to the accumulator's threads. If you need to replace the accumulator in the future, you'll need to buy another low side adapter fitting.

https://www.4s.com/en/ecata...9976&type=p&search=s

Four Seasons part number 59976

[This message has been edited by RWDPLZ (edited 09-20-2023).]

quote Originally posted by RWDPLZ: The adapter is a one-time use and seals to the accumulator's threads. If you need to replace the accumulator in the future, you'll need to buy another low side adapter fitting.

I'm sure this is something most of us didn't know. (filed in memory for future use)

What about the switch on the accumulator? It appears to be plastic threads in it.

[This message has been edited by fierosound (edited 09-21-2023).]

quote Originally posted by Raydar: The 4.9, as installed in a Fiero by TFF, does not utilize any pressure switches. At all. Mine worked fine (for probably 8 years) right up until it didn't. Coming back from Indy, I blew out a high pressure hose at 80 MPH. Was pretty spectacular. Thought I had blown an engine, based upon the noise and smoke. When I rebuilt the A/C system (complete flush, and new accumulator and compressor) I added a high pressure switch. I did not add the low side switch, as it seemed to be redundant to the pressure/cycling switch in the front. (Yes... I understand the difference, and am willing to put up with it.)

That is correct Ed Parks hooked up the A/C in his swaps without a pressure switch but on a full system some of his setups blew hoses. The 4.9L A/C system uses only one high pressure switch and that goes into the ECM to control the compressor clutch and cycle the system. You can add a 10mm switch port to the high side line and use a pressure switch to keep pressures within operating specs and restore PCM control.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
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