So I evacuate and begin to charge the system after the R134 retrofit.
It's got a new accumulator and new hi-pressure cut-out switch, new expansion valve, new evaporator and power to the compresssor clutch. I start to charge like the book says, after a pound of R134 was added I go to turn on the A/C. Compressor won't turn on and "act like a sump" like the book says. So I get the idea to jumper the cut out switch. Compressor kicks on, drains the remaining first can of R134. Continued to charge after checking it (low, of course) and in the meantime the cut out switch still wouldn't close. I'm noticing the orfice tube starting to frost, but the air was blowing cold. Then the compressor started making a squealing noise (not the belt, checked it). I made sure to put four oz. of the R134 oil into it, which came with the retro kit, as well as the 2 oz. into the accumulator, condenser and evaporator. Everything flushable was flushed two or three times before reassembly & evac.

So what could have gone wrong? Stumped on this one.

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D.R. Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03

 

So what is your question...why wouldn't the pressure switch stay closed or why is there frost on the evap.???? Frost on the evap usually means you are low on refrigerant. Asfar as the pressure switch I have never had to jump one out. I always replace parts, flush system, add necessary oil to replaced parts, compressor gets 2oz. of oil then spun by hand 10-15 rev., accumilator gets 2oz. oil, condensor 2oz of oil.Pull system into a vac. for at least an hour, remove vac. pump and let gauges remain to see if you have any leaks, when pulling a vac. on system start on high side and see if low side gauge reads the vac you are pulling this will usually tell you there are no obstructions in system. Put 1 can as liquid on high side 2 if it will take it. Wait a min. or two then turn on a/c to max cool. Add the remaining charge as a gas on low side. If compressor is making noise add 1 can of oil charge. DO NOT OVER ADD OIL you will ruin your compressor. Make sure you are using the proper oil. If retrofitting you really should flush system to remove as much of the mineral oil as you can. Make sure that all or most of the flush is pushed through the system as any remaining flush will shorten the life of system.

 

I guess the hex here is why the compressor switch wouldn't close, even after I added the first two lbs of refrigerant which should have been enough. I figure it may be defective, but how can I test it?
The only other thing that I think may have gone wrong was that I was measuring the temp inside the car and I left the can of R134 kind of wedged in between the strut tower and the water bottle line. The can flipped over while charging the system-did it wind up dumping liquid in there instead of a gas?
Like I said, i'm totally new to A/C and this is all a big trial by fire. Just trying to stay cool while it's +95 deg outside. Any advice &/or help will be greatly appreciated.


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D.R. Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03

 

So in doing this, how should I hook the gauges up? When I evac'd I hooked up the blue low side hose to the suction side and hooked the red high side hose to the vacuum pump-do I just switch them around, switch the adapter fittings.....?

Before I put everything back together I flushed the evaporator (new) the condenser and the hoses about 3 times apiece, then ran the shop air thru them to blow out the remaining flush. I used the Castrol/Factory Air R134 retrofit kit. Before I remounted the compressor I put 4oz of the oil that came with it (as per manual's instructions) into the port on back which is more towards the center, but I didn't turn it by hand. Is that where I went wrong?

P.S. I found the problem with the switch, the O-ring I used was too large in diameter and covered the hole inside the fitting.

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D.R. Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03

 

Hook up the gauges with the blue on the low side, red on the high and the center which usually is yellow to vac pump. Run the vac pump and open the valve on the high side and you will see the reading on the low side gauge. If it is pulling a vac. throughout the entire system then you can open the low side valve and pull through there also.

What type of oil was it that came with the compressor. You would want to use PAG oil for a retrofit. I have never used 4oz in the compressor but if that is what the manufacturer said than do it. You should cycle the compressor by hand to prime and lubricate it. Some new or rebuilt compressors will leak out of the front seal for a couple of minutes don't be alarmed by that.

Remove the belt on the A/C and cycle it by hand to make sure it is not seized. It should provide resistance but you should still be able to turn it.

I am glad you found the problem with the switch since I was stumped by that.

 

Hey Custman, thanks!! A/C works great now. No leaks, no noise, just cool air. Turns out I made a bad judgement of belt tension and it WAS the belt squeaking after all.

Now my only question is, should the compressor be cycling (on average) 5 sec on, 5 sec off, both while idling and cruising? Also when the compressor is engaged, I can actually "feel" it load the engine some-is this normal? Sorry for all the q's, just want to do this right.

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D.R. Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03

 

On a V8 you really should not feel it come on. I dont want to alarm you but the after the shop converted my whole system to 134a and put a new compressor on it, I could feel the thing loading up the engine. And my engine's got some *****! LoL... It turns out it was a bad compressor. It was still blowing air and all, but after they replaced it I cant feel it turn on at all!

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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car !

 

On my T/A It cycles on and off at idol to about 1100 rpm. then remains on. On my friends 84T/A it remains on...to tell you the truth I don't know which is correct.

I'm glad you found your problem was as simple as a belt

 

I just noticed something last night, also. There's what appears to be an adjusting screw in the center of the cycling switch visible with the plug removed. Do I need to adjust this thing for a certain pressure?

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D.R. Stevens
1984 Trans Am 305HO L69
1991 Firebird 305 L03