1990 AC question

[jrd1990zr1]

I am getting code 09 which is low Freon. I am running through the diagnostic in the 1990 FSM and it says to add 1 lb. of R12. The AC clutch is not engaged so my question is, will I be able to add the Freon through the low side of the system without the AC clutch engaged? Has anyone done this in the past?

Since the car is almost 35 years old I have read that the seal at the front of the compressor is the likely leak point. Any suggestions on a source that will rebuild the compressor for either R 12 or R 132.

BTW I know I can't mix the two refrigerants, Should the compressor be the culprit maybe it is time to convert the car to the current refrigerant. Thoughts?

Thanks.

[Corvette95]

In my experiece is unless it is totally out, the compressor will kick on as you add the 1lb. If it doesn't start you can unplug the pressure sensor on the a/c line and jump it to manually start the compressor. I am not 100% sure exactly which plug it is as I would refer to the FSM if needed so it would be good to look up the exact plug location just in case but I think you will be fine getting it to come one with just the can of freon when you crack it open. I still run R12 too.

[mlipmd]

If the Freon level is that low that the compressor will not engage, you have to bypass or short the low pressure switch to turn on the compressor to get Freon into the system. You will not be able to add Freon to the system unless the compressor is operating using the store-bought cans of refrigerant. And the amount of Freon needed will depend on the low and high pressures in the system, which is way more accurate than saying "add 1lb. of R12". which may be a great excess.
There are many places for leaks to occur, mine was from the Schrader valve on the high pressure line and was cured when I replaced that valve stem. You have to find the leak source before just adding more Freon (which can be done with a leak detector or a UV light dye detector) before assuming anything or just replacing parts hit and miss' till you find it. If you just refill the system you are wasting your time and your money as the leak will persist and you will soon be back where you started from.
You need to do some research and read about the AC system and watch some videos on this, which is way more valuable than just getting some advice, good or bad, on here.
Or bring it to a professional and have someone else look at it.

[jrd1990zr1]

Originally Posted by mlipmd

If the Freon level is that low that the compressor will not engage, you have to bypass or short the low pressure switch to turn on the compressor to get Freon into the system. You will not be able to add Freon to the system unless the compressor is operating using the store-bought cans of refrigerant. And the amount of Freon needed will depend on the low and high pressures in the system, which is way more accurate than saying "add 1lb. of R12". which may be a great excess.
There are many places for leaks to occur, mine was from the Schrader valve on the high pressure line and was cured when I replaced that valve stem. You have to find the leak source before just adding more Freon (which can be done with a leak detector or a UV light dye detector) before assuming anything or just replacing parts hit and miss' till you find it. If you just refill the system you are wasting your time and your money as the leak will persist and you will soon be back where you started from.
You need to do some research and read about the AC system and watch some videos on this, which is way more valuable than just getting some advice, good or bad, on here.
Or bring it to a professional and have someone else look at it.

I understand there are numerous places for a leak to occur, I have every intention of using an UV dye to find the source of the leak. However in order to add the dye, I have to charge the system first. The "add 1 lb. of R 12" comes directly from the 1990 FSM, which is why I asked the question if the system will take refrigerant without the AC clutch engaged. The FSM as written implies it will, I was asking if anyone else had encountered this condition. Additionally there is no mention in the FSM about jumping the low pressure switch. There is a note in the FSM that the compressor should not be operated without freon in the system.

[rufcar]

I just did my 88 I did the ne compressor last yr in my 90 zr1 also. The compressor wont kick in with too low freon plus as you add it the sensor has the compressor kick on and off frequently as you add freon it slow down. I too had leaks as my 88 is a Challenge car and the ac has not been used in a long time. We found 2 leaks 1 was the Schrader valve itself. The other was the top aluminum supply to the firewall. The O ring was deteriorated . So now I am checking weekly to see if we got them all.

[jrd1990zr1]

I tried to charge the system using the FSM procedure, no luck. Unfortunately there is no one locally which can work on a R12 car, good old NYS has banned R12 Freon and gives heavy fines to mechanics who use R12. So it looks like I will have to go the R134 conversion route.

I have a local shop which will do the conversion early next month. So much for keeping the car all original.

[WARP TEN]

I had Marc Haibeck convert my'93 to R134 many years ago. He said, per GM's directive, no A/C equipment had to be changed, just change to fittings and fully evacuate the system. You might check with him on how to do it. --Bob

[Mystic ZR-1]

John
"What we have here is a failure to communicate"
Just sent ya a text, maybe that'll work?
Doug

[jrd1990zr1]

Originally Posted by Mystic ZR-1

John
"What we have here is a failure to communicate"
Just sent ya a text, maybe that'll work?
Doug

Gee, I called you twice, I'll try again

John

[Young1]

There are kits out there.
New compressor
New dryer
New expansion valve
New Schroeder valves and O rings throughout.
All lines and condensor and evaporator have to be thoroughly flushed because R12 oil and R134 are not compatable.
Who do you trust to remove the plenum?