So I’m starting to address all the squawks on my new to me 88GT. One of which is the air conditioning which Is all original and does not work. Before I fire up the parts cannon I like to take a systematic approach to learn the system and figure out what truly is broke. It would be very helpful if someone could give an order to check things in so I don’t go down any rabbit holes. Another words, “A” must be satisfied before “B” will work which then alerts “C” to work etc... What I know so far: The HVAC control panel- The blower motor functions on all settings The Hot/Cold blend slider is functional The push buttons work and direct the air to the proper vents When I push any of the air conditioning buttons, max norm b/l, nothing happens. By nothing I mean: compressor clutch does not engage, cooling fan does not turn on, no rise in rpm. I know ultimately the clutch should engage but I’m not sure if other items need to be satisfied before that will be allowed to happen. Any and all input would be greatly appreciated.
Prepare for incoming flames to use search as this as bren beat to death.
The problem with most of these are they were R12 and when R12 was banned the systems were abandoned and never recharged/repaired when they finally lost enough charge to stop working.
You will find 2 options that are commonly posted. The cheap way and the right way. (We wont go into the extremes)
I just did the system on my car in August. Unfortunately i had quite an adventure because my under car pipes had pin holes and my AC to chassis hose was broken so at one point i had removed the AC and lost the brackets and had to find them (lucky i found mone in my parts)
Thanks for the reply and warning... I have actually searched and read a bunch of threads regarding ac on the forum but most seem to send guys in different directions and/or are related to updating to r134. I probably will do the conversation, maybe sooner than later based on necessity, but in the meantime I’d like to know for sure what component(s) have failed. Maybe there is a systematic approach that has been covered and I just missed it.
If / when I need to do the conversion, I’m definitely a do it the right way kind of guy. May cost more up front but “buy once, cry once”.
In the mean time maybe someone could spell it back out or reference the thread contains the info. I always like to hear other people’s experience as well.
I would say if you are 100% going to do it. Make sure all your components are in place. Buy a new Dryer/accumulator Orifice tube Orings And compressor (People will argue about the compressor but it was built for the r12 oil and has r12 oil in it. Its also been out of service for awhile and you have no good way of testing it or knowing how much life it has left. You will have to discharge and recharge the system if its bad or goes bad $350 is worth not worrying to me) Also need the right pressure sensors.
Remove the AC to chassis hose and send it for rebuild to R134a. Replace the orings and such and while each joint is open and the chassis to ac hose is off run a bunch of flush through the system. You want to get all of the old oil out. Depending on how well you get the old oil out will depend on if you use pag oil or Ester oil. Your rebuilt compressor will probably come with PAG. pag is incompatible woth the r12 oil.
Now some people will say do the condenser. I decided to just inspect it.
Now that you have all of the orings replaced, and new components installed run a vacuum. Id make sure it holds a vacuum over night. Then you can charge and hope. I think i dropped over 1k in just parts to retrofit and charge the system. This didn't include a condenser.
The first step in A/C diagnostics is hooking up a gauge set, to the high and low side ports, and checking pressures, with the car off, then withe the engine running (unless pressures are 0, then evacuate the system with a vacuum pump and see if it holds vacuum).
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Remove the AC to chassis hose and send it for rebuild to R134a.
This is usually unnecessary, unless the hoses are leaking.
O-Rings are a good idea, EXCEPT the two at the condenser, Sometimes the fittings corrode together and you'll damage the lines and/or condenser trying to get them apart.
New orifice tube and accumulator with new desiccant are a must.
The first step in A/C diagnostics is hooking up a gauge set, to the high and low side ports, and checking pressures, with the car off, then withe the engine running (unless pressures are 0, then evacuate the system with a vacuum pump and see if it holds vacuum).
This is usually unnecessary, unless the hoses are leaking.
O-Rings are a good idea, EXCEPT the two at the condenser, Sometimes the fittings corrode together and you'll damage the lines and/or condenser trying to get them apart.
New orifice tube and accumulator with new desiccant are a must.
I will argue he said its all original. I will take his word and say the hoses are not R134a compliant and also heat damaged from years of riding above the cat. I will also argue you will still need to pull the compressor to drain the r12 oil and replace the pressure sensor. Lastly because im in a mood ill argue hooking up gauges to an R12 system is mostly pointless unless you have the licensing and certification to properly evac and discharge an R12 system. If you do and it comes back with pressure you need to take it to a certified ac shop that can evac/discharge that system properly.
Gonna jump in here for a bit. As has been said, many posts on how to do the conversion. Here's some more info on the troubleshooting.
For the compressor to engage, there has to be a minimum amount of freon in the system. There is a pressure switch that measures this and closes (mounted on the accumulator), allowing the compressor to run, but only when there is enough pressure. If the system has leaked down ( very likely), then the switch is doing it's job protecting the compressor from running without Freon ( and the oil it helps circulate). Putting a set of gauges on the system will tell you it you have any freon left in the system. You can also check just by depressing the Schroeder Valve on the AC port, but be careful!! Wear eye and hand protection.
If there is no pressure left in the system, then you will need to find the source of the leak. Possibly dried O-rings, the seal on the compressor shaft, etc. Mine was a hole worn into the condenser due to vibration. This is when a conversion starts to make sense. Flush the lines, and condenser, replace all o-rings with green ones, drain as much of the oil from the compressor as possible and replace with an equal amount of Ester Oil ( Compatible with the old Mineral oil), add 3 oz of Ester oil to the new Accumulator, re-assemble and test for leaks again. Once you are leak free, then you can Vacuum and recharge. If the hoses are leak free, you can re-use them. They will leak a little R134a over time ( molecules are smaller), but they work. Replacement hoses are not terribly expensive, and are a good upgrade.
If you have pressure in the system, then you need to attach gauges and see how much you have. Less than 60 psi means you are low on freon, and a top up could get you running again ( until it leaks out again). If you have much more than 60 psi, then it could be a bad Low Pressure Switch, mounted on the accumulator. These pressures are not accurate- just guesses, but you see that some pressure is much better than no pressure at all. Since you have an all original system, with R12, you would need to source some additional R12 to bring the system up to full potential ( Ebay).
------------------ '87 GT , '00 3800 Series II SC, 4t65e, Vue Power Steering. (SOLD)
first thing to do is check and make sure all connectors are connected, there are three on the unit itself one can be seen by the belt, the other two are tucked away behind and you can only see one from the engine bay so look from underneath the drivers side
Hey guys Thanks for the replies and suggestions. I appreciate the direction as well as the tips for a r134a conversion. Hopefully I can get to it within the next few days and I’ll report back. If anyone else has some tips and tricks to offer I’d appreciate it as well.
I believe that flush is OK for the condenser and evaporator but not for the A/C rubber hoses. The original thought on a conversion was that R-12 lines and R-134a lines are made of a different material and flushing out the R-12 mineral oil coating on the old hoses could lead to leaks. This is why I just blow the old oil out with air, then replace the accumulator, orifice tube, compressor and O rings before recharging with R-134a and Ester oil.
------------------ " 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" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
