[idk999]

Okay, so my AC didn't work. The compressor wouldn't start, nothing... I spent months trying to figure out what was wrong. Took it to a shop -- they spent two hours, said it was electrical but they needed more time. Didn't have the cash. $160 down the drain -_- I tested the CCRM -- pin 30 or something didn't work, so I found the problem. I ordered a new CCRM off of Ebay, and put it in today.

The car runs fine. Only, now whenever you turn the AC on you can hear everything starting up, but it's still warm. You can hear the freon decompressing when you turn the car off, etc. But the AC still doesn't work... and then there's this. Every ten seconds there will be this "click" noise, the idle will drop and the car will shake. Then it'll be fine -- for another ten seconds. It's coming from the left side of the car, I think, but I'm not sure. I think it's the compressor, as that would make sense -- everything else starting up but no cold air?

So question: does it sound like the compressor? If not, could it be something worse? Could it be the CCRM, or could the compressor be bad?

 

[white-lightning]

Check to make sure the a/c cycling switch located on the a/c accumulator is connected firmly. Also make sure you aren't under/overcharged with refrigerant.

 

[idk999]

I checked the freon pressure as you said -- I believe that's the problem. Here's what I found out:

When you check the pressure with the car off, it's somewhere around 70psi to 100psi if not higher, so it's pretty high. Once the compressor comes on, the pressure drops to something low and pretty okay, only then this happens: the pressure CLIMBS to 45psi. Once it reaches 45psi it CLICKS, the idle drops, the car shakes and it the pressure drops. Then, it does this all over again.

So it seems like the freon pressure is too high, and that there's a safety mechanism that is shutting the compressor off. Before I start bleeding the freon out, though, I want to be sure. Does it sound like the freon pressure is too high, or could it be something else? If so, what should the freon pressure be at when the car is off? When the compressor is on?

EDIT: I just read on the car that it should have no more than .79kg of R-134A in it. What's that converted into psi...? haha -_- It's a '98 Escort SE Wagon by the way, if it matters -- I forgot to mention that.

 

[cklaubur]

Around 45-55 psi is normal, depending on ambient temperature. How low is the pressure dropping when the AC is on? The low pressure switch will shut off the AC if the pressure drops to around 20 psi.

Casey

 

[madmatt2024]

Really? It seems to me that that the pressure is too low.
The car shaking is when the compressor is on, sucking the refrigerant and making the pressure low, it gets too low and that trips the low pressure switch, then once the compressor is off, the pressure builds back up enough for it to turn back on, its called cycling. The pressure however should usually be about 30-35 PSI when the compressor is running on a system using R134a. The pressure when the car is off is irrelevant.

You need to tell us the year and version of car you have or what refrigerant the car takes.

 

[madmatt2024]

Double post.

 

[idk999]

Yeah, sorry about that -- I edited my post a third time when I realized, lol -_- It's a 1998 Ford Escort SE Wagon. R-134A refrigerant.

EDIT: Also, wait -- how do I get an accurate reading, then, if the pressure keeps jumping? :? Like I said, it keeps going from something low to 45psi, and then back down again. So I don't know what the real reading is -- I can only assume it's over 45psi? (I'll get the reading on what it drops to in literally five minutes, by the way -- I'll edit this post with it) I just don't understand how it could be that I have too little? If it's supposed to have around 35psi, and if it's jumping above 45psi, doesn't that mean that it would have too much? And that it's shutting off because it has too much? I just don't want to go ahead and put more in, and have the thing BLOW UP, you know? 8O

2nd EDIT: Okay, so it starts at 15psi. It jumps from 15psi to 45psi in about five seconds, it clicks, the idle drops, the car shakes and it falls back to 15psi, and then does this ALL OVER AGAIN >.<

 

[denisond3]

There are tables you should use to check that the pressures are correct. It will depend on the ambient temperature, there are different tables for R-12 versus R-134. And they will be with the compressor operating, and the gauges showing those pressures.
Sorry to say I dont have time for a google search to find any tables, but I know some are 'up' on the internet.

My very rough rule of thumb (for a.c. systems in Escorts anyway) is that at an idle the compressor should run full time - if the air temperature is over 85 fahrenheit. If its only 70 or 75, the compressor might cycle, even with a system properly charged up. If its 90 f and the compressor cycles, i think its either low on freon or something else is wrong inside the system.

 

[idk999]

Well let me ask you this. You know those cans of R-134a that are sold at Autozone? I read online the other night that they're dangerous, lol :? I guess because of the "stop leak" stuff in them -- it gums everything up like glue. Is this true?
And one more question haha. So previously some had been taken out, as I said. You know the oil that's supposed to be in there? Is it possible that some of that might have been taken out, too? In which case, wouldn't it be counter intuitive to just put more freon in, as the compressor wouldn't have enough oil? Maybe it's best to just take the car to a shop and have them fiddle with it?

 

[madmatt2024]

Taking it to a shop is best but you can safely do some stuff yourself. Not all cans of refrigerant have the stop leak junk in them, you can get just plain R134a in a can with nothing else. That is what I used when I had to add some to my car. Usually, its just the refrigerant that leaks out and not the oil, meaning its safe to add just refrigerant. Also, having too much oil or mixing oils types is bad so avoid the stuff that contains oil if you're just topping off your charge.

 

[idk999]

Ehh... all right. Last, last question, I promise this time, haha Is it really safe to just add refrigerant while the compressor is cycling like this? Jumping in pressure from 15psi to 45psi, and all? Is there a certain time during this cycling that I should add refrigerant? And what if it really has too much...? I know that you said it more than likely has too little, and that's whats causing this. But just in the event that's the case -- where it has too much, could I really do that much damage by further over charging it? Or would the over-pressure cut-off switch take care of everything?

 

[juggalo]

here's a chart of temperature and a/c pressure from my EZ-Chill conversion kit.

65* 25-35psi
70* 35-40psi
75* 35-45psi
80* 40-50psi
85* 45-55psi
90* 45-55psi
95* 50-55psi
100* 50-55psi
105* 50-55psi
110* 50-55psi

hope this helps

 

[denisond3]

The over-pressure switch is 'SupposeD' to shut down the compressor, yes. The only thing to remember is that as the a.c. hoses age, they dont get stronger. A hose splitting open is -possible-, & could be darned unpleasant, and involve subfreezing stuff blowing around: So please do this wearing a decent pair of safety goggles, and in a well ventilated area. I would much rather do it in the driveway with a large fan blowing from behind me.


The directions on the can probably say something about how to hold it. If you hold it with the opening -downward- you are letting liquid freon go into the system - which might jam the compressor momentarily. If you hold the can with the opening -upward- you will only get freon gas going into the system. Its supposed to be put into the low pressure line anyway. That is where you should see the pressures listed in the table above. The pressure in the can will be a good bit higher than in the low pressure line with the compressor running, so it wont be a problem to have it go into the system.

Pressurized refrigerants & systems should be treated with a lot of respect.
I will rebuild engines, rebuild transmissions, & replace brake lines; but since my daily driver runs fine without an a.c. system, it let it die. I didnt want to spend the money to get it repaired by someone who knows what they are doing.

 

[idk999]

It works! Whooo! Thanks everyone so, so much! I haven't had AC in this car for an entire YEAR, so it feels incredible to actually have it back! I just put a little in, and the time in between when it cycled slowed down. I put a little more in, and it stopped all together. I topped it off to 35psi, and it runs cold as ever! Thanks so much!

EDIT: Okay, maybe not so done after all. Everything works, and the AC is ice cold. Only, the same sound I heard before? The compressor? Well, when it was 90 out today it went away. Once the temperature dropped tonight to 75? Not so much :? The sound came back -- it doesn't immediately stop, though. It goes from 25psi or something all the way up to 45psi, but very, very slowly. Is this normal, due to the colder temperature? Or do I still need to add more freon? Everything's still ice cold, whether it's doing this or not, so...

 

[madmatt2024]

It will start to cycle more often once the outside temperature gets colder. You could add a little more so its at 35 psi when its 75 outside buy you are probably fine.