Question concerning A/C
Discussion
I am having problems with my air-condition system (std., supplied by factory). It is still working (=cooling) but does all kinds of strange noises. First some hissing when I switch it on, then a slight squealing noise when I accelerate (a bit like a supercharger), worst is at idling, some loud knocking sound, sounds like the engine is falling apart (or like running on some cylinders only or timing completely off). Also bad in fast right turns, some strange rattling noise then. First I thought it is some problem with the engine but when I switch A/C off all problems are gone. Or could the A/C disturb timing or cause any other ignition problem?
We have checked the A/C filling (is ok), the fixation of the compressor and tension of the belts, everything seems to be ok.
I have done now approx. 9.000 mls., most of the time with A/C on. So maybe the compressor or other parts have a short life-time if abused in an Ultima(= often revved high)?
Anybody of you having any similar experiences?
Asked the factory for quotation on a replacement compressor, need to solve it fast. Over the weekend I took my wife for a 100 miles drive, after half of the distance I had to switch off A/C, must have had > 40 deg. in the cockpit, my wife was nearly cooked and fainting, refusing to get into the car ever again...
We have checked the A/C filling (is ok), the fixation of the compressor and tension of the belts, everything seems to be ok.
I have done now approx. 9.000 mls., most of the time with A/C on. So maybe the compressor or other parts have a short life-time if abused in an Ultima(= often revved high)?
Anybody of you having any similar experiences?
Asked the factory for quotation on a replacement compressor, need to solve it fast. Over the weekend I took my wife for a 100 miles drive, after half of the distance I had to switch off A/C, must have had > 40 deg. in the cockpit, my wife was nearly cooked and fainting, refusing to get into the car ever again...
The knocking sound may be due to the system being overcharged. Start the car up and turn on the AC system at full blast and then rev the engine to about 1500 rpm and hold it there. Then check the hose leading to the compressor, if it is sweating and icing up you are getting liquid freon into your compressor. This is called slugging and the compresor is trying to compress a liquid which cannot be done and that would cause the knocking as well as ruin the compressor. if this is the case release freon until the hose just outside the AC unit under the dash is cold when running as described above and you should be ok. Your compressor may be ruined from the slugging so it may be you have to replace it and recharge the system.
As Ed said, if you have too much freon in the system the compressor will rattle/knock. It will also do this if air was introduced into the system when charging, or if the system was not evacuated (place a vaccum on the system) before being charged as the air has moisture which will allow ice to form in the freon and will also cause the compressor to rattle.
If you put gauges on the high and low side and see abnormally high readings, then the system is overchaged. If they are either at the correct readings or a little low, it could be air in the system causing ice to form.
Since you also state that not only is it making a rattle/vibration noises but is also making a whistling noise, I am willing to bet it is over charged. This is the number one reason for failure in A/C systems.
You can get two types of freeze ups that can cause various problems as well. One is an exteranal coil freeze. This is caused by the inability to wick away the condenstation off the coil fins. In new installations this is normally caused by not having placed the thermostat probe properly in relation to the condensor which does not read properly and allows the compressor to stay on longer then needed and allows the coil to freeze. Or can also be caused by too much humidity being introduced into the condenser. If you are getting low volume of air out the vents over a period of time, and large puddling of water under the car after extended periods of rest it is an indication of external condenser freeze.
The other is an internal freeze up. This is normally indicated by the A/C cooling fine at low speeds, but after a high speed run down the highway the system blows sufficent air but no longer blows cool air, this is caused by air in the system, which causes ice to form and freeze the internals. This will require the whole system be evacuated and re-charged to resolve the problem. Also if this occured, the dryer will be contaminated and will require it be replaced as well.
Good luck.
Michael
If you put gauges on the high and low side and see abnormally high readings, then the system is overchaged. If they are either at the correct readings or a little low, it could be air in the system causing ice to form.
Since you also state that not only is it making a rattle/vibration noises but is also making a whistling noise, I am willing to bet it is over charged. This is the number one reason for failure in A/C systems.
You can get two types of freeze ups that can cause various problems as well. One is an exteranal coil freeze. This is caused by the inability to wick away the condenstation off the coil fins. In new installations this is normally caused by not having placed the thermostat probe properly in relation to the condensor which does not read properly and allows the compressor to stay on longer then needed and allows the coil to freeze. Or can also be caused by too much humidity being introduced into the condenser. If you are getting low volume of air out the vents over a period of time, and large puddling of water under the car after extended periods of rest it is an indication of external condenser freeze.
The other is an internal freeze up. This is normally indicated by the A/C cooling fine at low speeds, but after a high speed run down the highway the system blows sufficent air but no longer blows cool air, this is caused by air in the system, which causes ice to form and freeze the internals. This will require the whole system be evacuated and re-charged to resolve the problem. Also if this occured, the dryer will be contaminated and will require it be replaced as well.
Good luck.
Michael
Hi guys, thank you all a lot for the advices!!
I had a specialist to check the system yesterday (could not be there personally, unfortunately). He thinks too that the system was overcharged. Reduced the freon filling to 350g (said that it was 450g before). He thinks that there is no air in the system, as they applied vacuum before they filled it last time, done by a different guy, though.
Drive test: All rattling and noises are completely gone!!
Downside: it does not cool a lot, air is not ice-cold as before, rather warm. 
Hm, don´t know what to do next. Could fill it up to 380g or 400g and try then? Or do you think that the compressor is damaged meanwhile and I should go for a replacement? How can I check whether the compressor works 100%?
All advices greatly appreciated!
Thanks,
Peter
I had a specialist to check the system yesterday (could not be there personally, unfortunately). He thinks too that the system was overcharged. Reduced the freon filling to 350g (said that it was 450g before). He thinks that there is no air in the system, as they applied vacuum before they filled it last time, done by a different guy, though.
Drive test: All rattling and noises are completely gone!!
Downside: it does not cool a lot, air is not ice-cold as before, rather warm. Hm, don´t know what to do next. Could fill it up to 380g or 400g and try then? Or do you think that the compressor is damaged meanwhile and I should go for a replacement? How can I check whether the compressor works 100%?
All advices greatly appreciated!
Thanks,
Peter
ultimacz said:
.......Downside: it does not cool a lot, air is not ice-cold as before, rather warm....
The guy who did mine made several adjustments (not sure what) whilst observing a digital thermometer with the probe in a dash vent and the doors shut. He said when he started he would have to guess how much to put in but could adjust it later so that may be what he was doing.
Steve
What is the delta between the inlet air and the outlet air?
With the A/C temp on coldest, the fan on meduim, the cabin closed, and sufficent air flowing over the condensor (I recommend placing a box fan in front of the condenser). Run the idle at 2000 RPM, and check the A/C outlet duct closet to the evaporator as you can get depending on how you duct setup is. The outlet air should be between 38-45 degrees F (sorry, I am in the US, so I don't do C
If not then you need to start more diagnostics.
Does the A/C cool fine when you first start the engine after it has set overnight?
1) If so, make sure that the evaporator is not freezing up.
2) The location of the condenser/fan may not be allowing for proper cooling of the freon, believe you probably have it mounted in one of the side pods. If it does not get good air flow, it can not disapate the heat needed.
3) Make sure that the heater hoses are hooked up properly and the heater valve is adjusted properly, have seen many systems hooked up backwards which sends hot water into the heater core when the heater is not being called for. One quick way to do this is to disconnect the heater hoses and loop them and then go out for a test drive.
4) There may be a restriction in the system. The expansion valve or orfice could have gotten clogged, this can normally be detected by having a tech. hook up gauges and take it for a drive and watch the high side for excessive pressure, or the low side extremly low (possibly even creating a vaccum).
Also keep in mind that newer R134a type systems do not cool at the same capacity as the old R12 systems use to. I wish they would have left well enough alone on that subject, but I don't want to start a tree hugger argument on an automotive board
With the A/C temp on coldest, the fan on meduim, the cabin closed, and sufficent air flowing over the condensor (I recommend placing a box fan in front of the condenser). Run the idle at 2000 RPM, and check the A/C outlet duct closet to the evaporator as you can get depending on how you duct setup is. The outlet air should be between 38-45 degrees F (sorry, I am in the US, so I don't do C
If not then you need to start more diagnostics. Does the A/C cool fine when you first start the engine after it has set overnight?
1) If so, make sure that the evaporator is not freezing up.
2) The location of the condenser/fan may not be allowing for proper cooling of the freon, believe you probably have it mounted in one of the side pods. If it does not get good air flow, it can not disapate the heat needed.
3) Make sure that the heater hoses are hooked up properly and the heater valve is adjusted properly, have seen many systems hooked up backwards which sends hot water into the heater core when the heater is not being called for. One quick way to do this is to disconnect the heater hoses and loop them and then go out for a test drive.
4) There may be a restriction in the system. The expansion valve or orfice could have gotten clogged, this can normally be detected by having a tech. hook up gauges and take it for a drive and watch the high side for excessive pressure, or the low side extremly low (possibly even creating a vaccum).
Also keep in mind that newer R134a type systems do not cool at the same capacity as the old R12 systems use to. I wish they would have left well enough alone on that subject, but I don't want to start a tree hugger argument on an automotive board
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