a/c compressor clutch not engaging

[themadness]

i just had a new compressor put on and a fresh charge of freon. i noticed the evening that the a/c now isnt blowing cold as it was the other day. we realized after inspection that the clutch was not kicking on.

here is what we do know.

the battery checked out so the alternator may be dying. there are other electrical oddities (turn signals, dome light not going off by itself like it should after you close the door) so i threw the alternator in as a possible cause.

freon leak. i dont have tags or insurance on the car yet so having it check for a leak will most likely wait unless there is a way for a noob to do it himself.

there doesnt seem to be any problems in the fuse box.

i havent checked the relays as i have no clue where to look. the only thing i do know is they are somewhere on the passenger side.

the drive belt always pops back up in my mind. considering the weird little things and the symptoms of the alternator. the compressor clutch issue popping up makes me wonder about the tightness of the belt being a culprit.

how to do isolate the clutch itself to check its functionality?

[DTMAce]

Here is the problem.

The clutch for your A/C will NOT engage unless one or combination of the following are met:

You have enough coolant in the system and you are using the A/C mode.
You have enough coolant in the system and you are using Defrost.
You have enough coolant in the system and the pressure sensor is working and you are using one of the above modes.
You have enough coolant in the system and the clutch wiring is connected.

Bottom line. The biggest reason the clutches fail to work, is due to the pressure of the coolant. If there isn't enough in the system, the sensor (usually located right below the top of the radiator on the passenger side connected to the pressure line coming from the pump) will not allow the pump clutch to engage, no matter what you do.
Now, secondary to that, yes, that sensor could go bad, the clutch could come unplugged or go bad, and the fuses could blow. Alternator working or not usually does not prevent the A/C from trying to engage.

I just helped a friend with a 99 GA with the 3100. Advance auto tried to tell him his pump was junk, and that was why his clutch wouldn't engage. I told him to pick up a can of refrigerant and let us try to prime the system so the sensor would trip on. Guess what, the clutch worked fine, however his pump is noisy as hell, so its still bad. But at least the clutch was fine. Sadly it works good though, even with just one tall can of coolant it still blows pretty cold air. But the pump sounds like it would explode at some point. And yes we used a can with oil included, for those that wonder.

I would be more likely to bet that when they installed the pump, they messed up a o-ring, or forgot one or something and it bled the coolant out, so now it doesn't work. That would be most likely.

If you are concerned about the belt, do a simple check.

Look for loose play in the belt. You should not be able to move it more than an inch or so without really having to push on it.
Look for large cracks, pieces missing, threads, etc. (small, tiny cracking is normal) 100k miles on a belt is usually all I will run them at most. I also change the tensioners and idlers at the same time. Make sure none of the pulleys wobble while its running.

If you hear jingling, bell-like sounds while the engine is running, most likely the bearing for the A/C pump's pulley is bad. But since you just replaced it, that shouldn't be happening. Keep in mind, this will NOT prevent the clutch from engaging. Just means the bearing the pulley rides on while not using the A/C is bad.

Hope it helps.

[themadness]

UPDATE


when the car cranks up the temp from the a/c seems to fluctuate. it goes from cool to warm, back to cool, and then levels out to mildly cool.

not sure if its related but my temp gauge on my cluster has stopped working.

[DTMAce]

The first part sounds like it may still be low on refrigerant. Not enough for it to cycle correctly. The other thing that can cause the same symptoms maybe is your A/C's cooling performance. Sitting in traffic not moving, or stop and go traffic, or the fan kicking on and off while sitting still/not moving much could cause this too vs going down the highway at cruising speed for a length of time. If you do that it shouldn't cycle. If it still gets hot and cold even at highway speeds then its definitely low on refrigerant.

When mine was working, it always did better at highway speeds than idling or slow traffic speeds.

Temp gauge on the car not working means that you may have an issue with the sensor or sensor wiring for the gauge. That can be found on the rear head of a V6 or the backside I believe of the 4 cylinders. The fan is controlled by the sensor at the thermostat location, usually up front where the hose going to the top of the radiator is attached to the engine.

And since you mentioned issues with voltages, etc, low voltages can make the gauges go funky too. I remember running the car on the battery for a short time one time when the alt died while driving, and as the voltage dropped stuff started working weird. Gauges went nuts, then the next thing you know I made it to my destination before the whole engine died. After all, if the computer loses power, so does your engine.

[themadness]

called the service guy and he said all that is part of the tune up is topping the freon. he said if the a/c stops blowing cold again that it would have to go to the radiator guy(duh).

the first thing i assume is a leak. how do i find it without a special guage or dye if possible? would there be something visual i can look for?

second, will the engine light come on if their is a leak or a component goes bad?

[pghturbo88]

called the service guy and he said all that is part of the tune up is topping the freon. he said if the a/c stops blowing cold again that it would have to go to the radiator guy(duh).

the first thing i assume is a leak. how do i find it without a special guage or dye if possible? would there be something visual i can look for?

second, will the engine light come on if their is a leak or a component goes bad?

I just did this on my LeBaron. Buy a can of refrigerant that contains UV dye and add as per the directions on the can. Run the A/C as you normally would over a period of a day or two. (Note that if you are still using R12, or if you have a full charge of freon, they have "universal" dye that comes in a small bottle and would be poured into your charging hose prior to adding the refrigerant that will transport the dye into the system.)

Buy a black light. They only seem to sell CFL black lights nowadays. Got one for about seven bucks at Walmart. In a dark place, open hood and illuminate the entire A/C system, one component at a time, with your black light. Pay particular attention to fittings and connections. Leaks will be pretty obvious, at it will look like something from the laser tag place or a cheap velvet Elvis painting. GL.

Oh, and even though some AC functions go through the ECM, I am not aware of any CEL illuminations related to leaks. Note that my 89 Beretta also has an A/C cutoff switch in the power steering line to disable the compressor if hard steers (i.e parking) are taking place. Bad electrical components are identified the old fashioned way, with elbow grease and a multimeter (my LeBaron problem was not a leak, rather, a bad low pressure switch inhibiting clutch actuation.)