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iTrader: (3)

My a/c compressor wouldnt turn on at all (85 TA 305 TPI). I tested the pressure with a can of R134 (with guage on the can) with Max A/C on.
She was empty,so I put approx 4 oz in, and it went up to 40 psi while running.
The compressor cycles on / off constantly,and the pressure builds up to 65 psi, then down to 35-40 psi as it cycles on and off.
The fan doesnt turn on when I turn on the a/c either, and blows hot air.
Possible problem .....Pressure switch? compressor?
Any help would be appreciated.THANKS!!!

Supervisor42

First thing to do is find out where the leak is, if it was empty. Unless it hasn't run in 4 years it should have some in it.
The radiator fan will not run on most models unless the high side pressure is above 250 PSI.
So far it sounds like a normal system with only 4 oz of referigerant.
The interior fan probably has no "low" speed or it would run when the control is on A/C. Check if there is a resistor in the top of the heater box that drops the voltage to the fan motor for medium and low. If the fan doesn't run on low it may be burned out.

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iTrader: (3)

Supervisor,
Im not sure how long its been empty,but the guy i got it from in December said it didnt work, and never used it since it has T-tops.He could have been B/S ing me.....not sure. I only put 4oz in cause the can said 45 PSI is normal pressure,and 65 is getting into "danger" zone,so I didnt want to screw anything up. Is it OK to put more in? What is the normal amount in a full system?
Also,the blower fan works fine..... the cooling fan never turns on with the a/c running. Isnt it supposed to?
THANKS !
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sorry, just realized what you explained about the fan turning on above 250 psi

Supervisor42

You really need a manifold gauge set (the one with the red and blue hoses) to monitor the high side and low side.
After the system is "full" continuing to add refrigerant until the low side is steady at 65 psi and above is the "danger" zone.
If you will notice the compressor pumps the low side down and shuts off. When the pressure rises to 65 psi the compressor is off.
If the system was "empty" you can put 3 cans of refrigerant total in it and it won't be too much. Getting it full "right" gets a little complicated.
I suggest putting in 3 cans total and checking it for cooling, then check it for leaks. If it is still working a month later, it doesn't have a leak.
Also don't forget there is an "oil charge" that may or may not still be in the system. If the oil charge is missing, the compressor will die.
Servicing the A/C system properly requires special tools and training.

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iTrader: (3)

Thanks Supervisor,
I know what youre saying about the proper guages and training.Me and a/c troubleshooting are almost non- existant.Im gonna try more R 134.
The can I have was 19 0z. will it take 3 19 0z cans?
What is oil charge? the can has oil coditioner in it also,so is that adding it ,or is that seperate oil level to fill/charge?
Definitely inexperienced with a/c charging systems ,Dude....sorry.

sofakingdom

iTrader: (1)

In the AC system on these cars, the compressor has no separate "crankcase"; rather, the refrigerant passes through the "crankcase" on its way to the cyls in the compressor. Therefore ALL of the oil in the system has to be added to the refrigerant. IIRC they call for about 6 ounces for the whole system.

You can't mix the R-12 oil and the R-134A oil. You ABSOLUTELY MUST remove ALL the R-12 oil in order to do the conversion and have it work even to the crippled extent that a converted system is limited to, and expect it to last. You could either buy a new compressor ($$$ughhhh$$) or disassemble yours, at least take the shell off, and clean the old oil all out with brake cleaner or something and let it dry for a few hours in the sun. You need to flush the evaporator and condenser and lines, and replace the accumulator and the orifice tube. Those last 2 parts are pretty cheep: the accum is about $30, the orifice tube about $15. Pour about 3 oz of oil into the SUCTION port of the compressor and 3 oz into the accum as you put it all back together. You can buy the oil in little bottles about the size of brake fluid, at practically any parts store.

If the system has been busted open, you'll need to pull a vacuum on it for a while (maybe a half-hour or so, more if possible) to let all the moisture that gets in it to evaporate out. You should be able to get the vacuum down to very near "30" (that's inches of mercury, not psi) on your new gauge set, and take the pump off and close up the system, and it hold the vacuum to at least "28" for at least an hour. If it doesn't hold vacuum, it won't hold refrigerant either, and you'll need to tear it down and find the leak. Me, since I'm lazy and stupid and hate to do the same work twice, I just take every fitting apart and replace all the O-rings, and cut the factory crimped flanges off and replace the rubber part of the lines with new, using the heavy-duty AC hose clamps (NOT heater-hose grade ones); that way I don't have to keep doing the same work over and over again.

When you buy gauges, I'd suggest getting a good high-quality set of them, not just the cheeepest chinesium thing you can find that has dials and says it's for AC; and a set of these. That way, you can also work on other things in the future, like house AC or older cars or whatever.

Sounds like a hassle; but there's not alot of sense in half-assing it, because it won't work well and/or stay working well if you don't do it right. Do it all ONCE, and enjoy it trouble-free for years. And on top of that, if you go to sell the car, it'll be worth ALOT more with working AC, than a busted one.

Supervisor42

No.
I thought the entire world used 12 oz cans. I was wrong.
The proper amount of refigerant is different for different year models, starting with a vacuumed out system.
The amount is usually listed on a label on top of the heater box.
You could also find this info in a Haynes manual.
The oil charge is difficult to measure because the oil circulates with the refrigerant. When the system stops circulating the oil puddles up in low lying places. Like the bottom of the accumulator, condenser, evaporator, filter, and compressor.
The only way to really know how much oil is in the system is to completely disassemble the system and pour it out of each part and start over .
The amount lost from a system is different depending on where the leak was.
For example:
Normal system leakage over time; almost all freon, almost no oil lost.
Slow leak on low side; mostly freon, little oil lost.
High side leak; all freon and lots of oil lost.
So basically you charge it up, find the leak, and try to estimate how much oil was lost and add accordingly.
Oil charges are available in small cans next to the R134a.
We're not even going to get into the different types of oil ...

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iTrader: (3)

Well ,fellas.....
I went out and got 3 cans of the 12 0z (with oil added already). I got 1 1/2 cans in her, and thats all she'll take. the compressor started running once the pressure switch sensed the charge.
It blows cold in all speeds, not ICICLE cold like a new car though. It IS a 22yr old car though......cant see or hear any leaks either.
BTW: the system was professionally upgraded ,cause the New jersey certification sticker is still next to the evaporator..... (hopefully done properly) so I figure theres no cross- contamination.
Its HOT AS HELL in NY right now, so its hard to tell if its the heat, or a crappy 22.00 half-assed guageless charge yet.
The compressor cycles on and off evry 20-30 seconds still too from the half hour of watching/driving . ???normal???
I guess ill keep an eye on the charge and give it a good drive on the hwy tomorrow.(dark and POURING outside now.
She definately wont take the 3 cans though.
tell me what ya think about the 1.5 cans..........
Thanks Guys!!!

Supervisor42

Does your car have the compressor on the driver's side and the long hoses running over to it? If so it probably takes more than the other models. Maybe someone with an '85 will read their sticker and chime in with the correct amount.
It also depends on how "empty" it was to start with. A system without enough gas to turn on the compressor can still have several ounces in it.
Try to find a buddy with a gauge set.
Also, you have to have the engine running about 1000 rpm to have the compressor pumping enough to get all of the gas in.
You had said you were charging it at first out of a 19 oz can. Is the 1.5 cans in addition to the first 4 ounces or did you empty the 19 oz can also?
You still shouldn't have enough in it.

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iTrader: (3)

I do have the driver side engine comp/long hose setup.the 1.5 cans is in addition to the 4oz yesterday.I know that i really do need a set of guages also. I only used abot 4 0z from the 19 oz can yesterday.(old can)
I'd say about 22 oz total in there total now.
should i try the 1k rpm and add more you think?

Supervisor42

Really need the gauges to see what the high side is doing. My '88 says 2.25 lbs of R-12 which is 36 oz. See if there is a label on top of the blower housing on yours. It'll be under the wiring harness.

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iTrader: (3)

I have bigger problems now.....
I tried adding more with the engine at 1200 rpm, same thing.wont take any more. the a/c belt looks like its "jumping" (or loose )when the compressor turns on.After driving about 20 mins, I pulled into the driveway,and noticed antifreeze leaking on the ground. My water pump is leaking at the seal.
Sooooo.... now i need to replace that tomorrow before I do any more a/c troubleshooting, (or overheat my engine) and I need to get the guages from my buddy.
I dont think the belt problem is related to the leak....Its just my luck that now the waterpump crapped out. TYPICAL!!!!!
Ill keep you posted, thanks for all your help so far dude.

BTW: the lines off the compressor felt pretty hot while was checking it after driving it.