94 gcl a/c blows warm

I'm not a mechanic, but what I've done is this. I've had pep boys evacuate the system and fill it with coolant, and he tested it and it shows no leaks, he even put in some green dye, but I would still only get cold air for about an hour. The compressor kicks in every 5 seconds or so then goes off again, on again etc, so I gave up. A year later the system still seems charged,and continues to do the same thing. I'm certain that there is no leak. Any thoughts?

Leo

While it's running, feel the pipes on either side of the compressor. It should be hot on one side, cold on the other. If not then I'd think there is a problem with the compressor.

Boths hoses are warm, anything I can do to further verify that it is in fact the compressor?

A little more info is needed here. You said the Pep Boys guy filled it and it got cold for an hour. Did it ever get cold again? If not, I'm thinking there's a leak somewhere in the system.

never got cold again, but whatever he put in the system is all still in there, and what I mean by that is that all the dye and coolant he put in seems to all still be in there cause when I press down on the pin the air shoots out, and if I put the guage on the connector it tells me that it's more than filled. I don't know the first thing about fixing cars, but I can fix anything with the right instructions.

You said "more than filled".... if it's over pressurized that is bad also.

latest update is this. I let out some of the coolant from the low side. and now it reads ok as far as pressure. Don't know what the high side reads. But the system doesn't seem to be losing any coolant, so I'm pretty certain that there's no leak. I've adjusted the screw on the top of the condensor sensor and now the compressor clutch comes on and stays on. The low side metal hose get's ice cold, but the air inside the truck is still not cold at all, not as warm as it was before when the clutch was cycling, but still not cold.

Something under the dash then? I don't know.

fisrst of all if coolant is in there something is wrong !! it should be refrigerant. type back what kind of pressure readings high (250)? low (30)? what screw is that you touched ?? how did you let out from low side ?? while engine is running try watching the gauge and when compressor kicks on take a note of pressures. if you post back can get better idea of what is going on. if compressor keeps cycling it's a good sign of life.

fisrst of all if coolant is in there something is wrong !! it should be refrigerant. type back what kind of pressure readings high (250)? low (30)? what screw is that you touched ?? how did you let out from low side ?? while engine is running try watching the gauge and when compressor kicks on take a note of pressures. if you post back can get better idea of what is going on. if compressor keeps cycling it's a good sign of life.
Sorry, I mean there's plenty of refrigerant in the system, and it's not losing pressure, I'll have to take a reading from the low side, I don't have the tools to check the high side. the screw I'm talking about about is on this cylinder shaped canister that connects to the compressor. If you remove the sensor there is a slotted screw inbetween the two contacts that plug into the sensor when connected. If I turn it counter clockwise or whatever makes it come out higher, the clutch starts to turn steady. I released a little bit of the refrigerant by simply pushing the pin in with a screwdriver on the low side where I connect the refrigerant, and it shot out pretty hard. I will check the change in pressure tonight and get back to you.

pressure reads 35 with engine running and clutch turning, then jumps to about 75 when I turn clutch off.

Was that it? nobody has any other thoughts???

you need more freon it should be in the 80 lb range on the low side

But according to my guage, it's already coming close to the yellow which indicates alert!

ive never had any luck with those gauges so I bought a real set. most of the time they are way off. If your compressor cycles constantly it means its low. If you adjust the pressure switch it will make it think that the pressure is higher than it actually is and it will never get colder.

I did adjust the pressure screw, otherwise the clutch go off and on every 5 seconds. but I'm almost positive there is no leak. Is there a rule of thumb for adjusting that pressure sensor screw? I find that it either makes the clutch stay on, or it cycles every 5 seconds, no middle ground.
I haven't had the system evacuated since last summer when Pep Boys told me it's not losing any pressure, but they also used a green dye in the system. I'm wondering if I should evacuate the system and re-fill it again.

just because there is no leak doesnt mean that it wasnt filled to the proper level to begin with.

I had a similar problem with my '96. I would have it recharged in the spring, and by august, it wasn't working. As it turns out, i needed a new evaporator. There were fairly large holes in it. Got that fixed, and no more problem.

ok sorry for not replying. no low side should NEVER be at 80 psi !! with compressor running. off when you look at the gauges, both gauges should reaqd about what your surround ing ambient temp. is 80 degrees or whatever. normal pressure would be around 30-40 psi low (25 or 20 psi low pressure cut out) and 200-225 high lisde (around 475 high pressure cut out) with compressor running and depending on system. post all symptoms and pressures if you haven't fixed it yet.

I have no way of testing the pressure on the high side without bringing it to a mechanic.

I have the same problem with my A/C on my 1994 GC.
I had a reconditioned compressor installed and charged by a qualified AC mechanic. Next summer I have the same problem. The unit cycles on for 2 secs every 10 secs. Nothing gets cold. Took it back and found that the system was still fully charged. The mechanic thought that maybe the mixing door was stuck and messed with that and said it was fixed....not.
He now thinks the condensor is plugged? Don't really want to pull the dash apart. Any simple way of checking a condensor / evaporator.