AC blowing but not too cool.

I replaced the refridgerant and it's running at about 40lbs. How can I tell if the compressor is kicking on and off. I think it is running because I see water dripping on the ground while it's on. Thoughts? It's a 98.

How did you replace the refrigerant? Did you replace the filter/drier and vacuum down the system for 30 minutes?

What side of the AC is running at 40lbs, there are two? Assuming its the low side, that is way to high, it should be running around 27 PSI. If its the high side, that is extraordinarily low, the compressor should NOT even engage with that pressure. Again, since its a '98, we are assuming its a R-134a system with R-134a in it, those pressures are different for each refrigerant.

Low side pressure being too high, can be from too little refrigerant, too much refrigerant or some sort of malfunction in the system. You can't tell unless you are also reading the pressure on the High Side as well, and compare the two.

The compressor has a clutch on the front of it, the plate on the front of the clutch stands still when the AC compressor clutch is disengaged, the plate engages the pulley that is spinning with the serpentine belt when the AC compressor clutch engages, which you would see the plate in the front spin with the pulley.

Where is the water dripping from? Depending on how humid it is, a poorly performing AC system can still cool enough to condense water out of humid air. A proper working system should have that water drain from the drain tube at the firewall, just below the evaporator.

The only final test of how well the AC system is working is: How cool the air is that is blown out of the vents, assumming it is being tested properly. You really need to know what both the High & Low side pressures to even to begin to properly diagnosis the system.

Rick Anderson said:

How did you replace the refrigerant? Did you replace the filter/drier and vacuum down the system for 30 minutes?

What side of the AC is running at 40lbs, there are two? Assuming its the low side, that is way to high, it should be running around 27 PSI. If its the high side, that is extraordinarily low, the compressor should NOT even engage with that pressure. Again, since its a '98, we are assuming its a R-134a system with R-134a in it, those pressures are different for each refrigerant.

Low side pressure being too high, can be from too little refrigerant, too much refrigerant or some sort of malfunction in the system. You can't tell unless you are also reading the pressure on the High Side as well, and compare the two.

The compressor has a clutch on the front of it, the plate on the front of the clutch stands still when the AC compressor clutch is disengaged, the plate engages the pulley that is spinning with the serpentine belt when the AC compressor clutch engages, which you would see the plate in the front spin with the pulley.

Where is the water dripping from? Depending on how humid it is, a poorly performing AC system can still cool enough to condense water out of humid air. A proper working system should have that water drain from the drain tube at the firewall, just below the evaporator.

The only final test of how well the AC system is working is: How cool the air is that is blown out of the vents, assumming it is being tested properly. You really need to know what both the High & Low side pressures to even to begin to properly diagnosis the system.

Click to expand...

OK it's pretty obvious I have no clue what I am doing. The pressure I am reading is from the connection atop the think aluminum line, running between the compressor and what I assume is the evaporator. It was the only connector that I could get connected to the gauge. The other two connections are as follows. One pretty much on the compressor and another plastic connector with a cap that screws on. The directions on the can said to connect it to the low pressure side. Is that the plastic connection.

And that's a big fat no on the filter and vaccuming the system. How do I do that?

thanks

It sounds like you did NOT replace the refrigerant, that you just topped off the system with a can you bought off the store shelf.

The hi/low sides have different sized connectors, so if the gauge is on the can you bought, then its very likely you connected it to the low side. Which the connector would be between the evaporator and the compressor.

If you have NEVER opened up the AC system, you should be OK topping it off. Any air or moisture gets into an AC system, the heat/pressure will cause it to form acids and destroy your system. Most likely, even if the system leaks so much that it will no longer work, the seals still hold enough refrigerant that it creates an overpressure and keeps the air/moisture out.

If air/moisture gets into the system, like you opened it up, requiring the REPLACEMENT of the Refrigerant, they you replace the filter/drier and vacuum down the system before putting in new oil and refrigerant. The vacuum removes the air, and causes any remaining moisture to boil at 40°F, that is why you hold the vacuum for 30 minutes to boil and remove any remaining moisture in the system. The filter/drier has a bag of desicant that will absorb any moisture or foreign material that may have still have remained. If you open the system and expose it to air, the drier's desicant bag will become saturated with absorbing moisture just out of the humidity of the air, thus you need a new filter/drier every time you open up the AC system.

You really don't know what is going on in your AC system unless you can read both hi & low side pressures. Your getting 40PSI on the low side, which is too high of a pressure, but without the pressure on the hi side of the system, we have no idea if that is because the refrigerant is too low or too high.

You may want to take it too a professional. About the only clue I could give you if you want to continue to service this yourself, you could mess it up, but, try putting a 2nd can of refrigerant on the system. If the can empties fairly quickly and the pressure starts going lower and you get better AC performance, then you were probably low and your doing the right thing. If the AC can empties very very slowly, or not at all, then its likely you've overserviced the system and need to recover some of the refrigerant you put in it.

You do know that your suppossed to service with the engine running at idle and the AC on its highest setting with the highest load, right?

Again, this is a R-134a system and you used R-134a, correct?

Yes it's 134a and I'm putting 134a in it. When I ran an initial reading I go 60lbs on the gauge. I'm assuming the previous owner overcharged it. Maybe it damaged the system.?

Yes to running it while charging it. Thanks

My advice to you is to take it to a professional and let them see what all is going on. They'll be able to see both high and low side pressures, determine if it's overfilled or underfilled, and how to fix it.

Also let it be known that the 97+'s have shotty evaporators in them....and I havent seen one yet that DOESN'T leak. And thats an all day job to replace if you do it yourself, or a very expensive (several hundred $$$) job if you take it to somebody, as the entire dash has to come apart.

Funny thing about r-134a, too little and it will blow warm. Too much, and it will also blow warm...and it doesn't take much variation to make it too much or too little.

glennv said:

Yes it's 134a and I'm putting 134a in it. When I ran an initial reading I go 60lbs on the gauge. I'm assuming the previous owner overcharged it. Maybe it damaged the system.?

Click to expand...

NO, not necessarily, it may have been low on refrigerant and you only partly topped it off, thus not getting the low side pressure all the way down to where it should be.

I can't argue with the advice of taking it to a professional, unless you know what your doing, you could mess up the system royally.

Don't forget, that is a cheapo, throw-away, gauge your using, it could be wrong.

If your willing to risk it, i.e. its not worth it to pay a pro to fix your AC, your only willing to spend the couple of bucks for some cans of refrigerant, if the system is blown, so be it. Then, I'd another can of refrigerant and add it, see if the pressure comes down toward that ideal 27PSI more.

Well I took another look at it and might have made progress. I checked the pressure and it droppped to around 25lbs once the compressor kicked on. I added just a llittle more refridgerant and then ran the AC for a bit. It does run much cooler than before. Then again it's only 40* out today but never the less it's much cooler than when it's on the plain old blower.

How long should the compressor cycle on and off for? Mine seems to go on and off every 5-8 seconds. Also, the pressure dropped about 10lbs on the gauge as it cycled on.

glennv said:

How long should the compressor cycle on and off for? Mine seems to go on and off every 5-8 seconds. Also, the pressure dropped about 10lbs on the gauge as it cycled on.

Click to expand...

Thats another sign that your still low on refrigerant.

The Low Side pressure is the same pressure the refrigerant is at in the evaporator. Since its a closed system, the pressure is always a direct relationship with temperature, and 25PSI is equal to 32°F. So there is a low pressure switch that cuts off the compressor if it drops below 25PSI, so the evaporator does NOT ice over.

If your LOW on refrigerant, the High Side of system runs out of refrigerant to pump into the evaporator to expand, thus it can't keep the supply of refrigerant in the evaporator (and keep it cooling) and running out of refrigerant causes the pressure to drop right away, the quick pressure drop causes the compressor to cut out.

Your suppossed to charge the AC system with the AC on its highest setting, usually recirculate air, with all the windows open and often it stipulated to bump up the engine idle to 1200 rpm or so. This is the heaviest load for the AC system, where a proper working AC system would have the compressor running constantly. At low loads, the AC compressor would cut on/off a lot to keep from over cooling/icing the evaporator, but at heavy load, the compressor should run constantly, never cycling on/off. Being low on refrigerant would cause it to cycle rapidly and not provide much cooling out of the system.

If you had a proper set of gauges, you could also read the high side pressure and most likely you would see you only build up about 90PSI on the Hi-Side, that should be 175PSI or greater, on a hot day it can get up to 220PSI. If the high side low on pressure that would confirm low refrigerant.

From what you told us, it sounds like your still low refrigerant and need to add some more, again your taking a risk here, cause it may be something else wrong. So it depends on what you want for your AC system, if your really want a good working AC system, either take it to a pro or get the tools and do the research to learn how it works. If you really aren't too concerned about AC, you could care less if it works or NOT, but are willing to spend a few minutes and dollars if it works, then trying adding more refrigerant yourself.

It's now blowing ice cold air but again it's only 45 out right now. The compressor is still cycling on and off ever 10 or so seconds. I think I'll play it safe and get it checked out when the weather gets warmer.

Take it to a shop, have them vacuum it out and then re-fill. Once you screw it up, you hve too much money at risk to take half measures.

glennv said:

It's now blowing ice cold air but again it's only 45 out right now. The compressor is still cycling on and off ever 10 or so seconds. I think I'll play it safe and get it checked out when the weather gets warmer.

Click to expand...

It sounds like its acting normally, as of now. However, it is better to do A/C work when it's warmer out. I would definitely take it to a shop when it warms up and have them check it.

Rick - you are the AC man!

Thanksf