Air conditioning issues

[akl]

I've got a 91 Jetta and the air conditioning isn't blowing cold.

The system still had some pressure but I thought it could be low so I added a half can of refrigerant which didn't solve anything. The compressor is turning on and the line from the compressor to the condenser gets quite warm. That's it, the evaporator lines aren't even a bit cool. Seems to me like maybe a line is kinked somewhere or is there a sensor that could be causing the system to malfunction?

Thanks

[jtanguay]

one can of refrigerant as in... R134a crap?  you can't just a can with that stuff.  system has to be completely evacuated, oil must be sucked out and a synthetic oil must be used in its place (non synthetic oil will goop up and probably lead to your compressor dying)

there are two sensors.  one that is a low pressure shut off which is simply that.  a shut off if the system pressure is too low (saves your compressor) and a high temp fan boost (to increase the fan speed on those hot days, which can also lead to a fan failure down the road due to high load on it)

i think there might be a switch in the expansion valve, to regulate flow of refrigerant in the evaporator, but i'm starting to doubt that.

i believe that your rad fan isn't coming on when the A/C is on.  does the rad fan even kick on when the temp is high enough?  not removing the heat from the condensor would lead to near zero cooling. (gotta move the heat somewhere!)

duracool is some pretty awesome stuff!  it can be mixed with other refrigerants (but most likely illegal depending on where you live) and is compatible with both types of oils, plus they even sell their own good brand of oil.

its late and i'm going off on random crap... a FAQ should be written up on the a/c system lol...  don't forget to change your receiver drier too... its a sponge that soaks up moisture (which your a/c oil likes to soak up and turn into acids... not good!)

maybe if i'm feeling adventurous i will take some pics of the a/c system and try to make up some FAQ for the DIYer's out there.

[akl]

I put RedTek 12A refrigerant in. Your right, I should have evacuated the system first. I thought it was ok because the manufacturer says it is compatible with most refrigerants but I now learned it is illegal to mix refrigerants. The product is also compatible with most oils so I'm hoping that won't be an issue.

Now that I think about it I don't think the fan is coming on. Even so, the line going to the condenser is too hot to touch and the line leaving isn't even warm.

[jtanguay]

yea... DO NOT let the a/c compressor run when the fan isn't kicking on.. you will either blow your compressor, or the pressure/heat from the refrigerant will blow through a seal (most common seal to blow is the one from the high pressure line that connects to the condensor)
 
even though it's illegal.. just don't tell anybody  :roll:  :lol: i think red tek is on par with duracool which is okay.  things that you might want to look into is finding out why the gas leaked in the first place.

so the a/c resistor is blown on your car...  i can give you a scenario that i believe happened on my car with the P/O.  hypothetical situation which is probably bang on!  ok so here it is:  P/o sitting in traffic with a/c blowing on MAX on a really hot day.  Rad fan overheats and the ceramic resistor blows.  this disables the low speed for a/c only.  now i'm not 100% sure if the high speed will turn on for the a/c without the resistor, but if it does, that would surely lead to the demise of the a/c fan.  on with the story... so now the p/o is enjoying his a/c and the fan is working super hard, max full speed and is constantly in an off/high state because of the high temperature high speed fan sensor switch.  the fan couldn't take it anymore, and just quit working.  something gave out...  and now the carnage.  compressor is still going... a/c condensor is getting super hot!  connection from the high pressure hose to the condensor expands, o-ring burns up, and then refrigerant leaks out of there until the low pressure switch turns off the compressor and saves it.  the motor overheats, and must be replaced.  they sell the car and i buy it  :roll:

i changed the condensor, receiver drier, and bought an r134a o-ring kit (comes with all kinds of o-rings!!!) and installed it all, and have decent a/c, although the high pressure valve was leaking a bit... you can just buy a tire valve tightener and that will work.  hopefully thats all it was!

whereabouts are you located?

[akl]

Ok, my mistake. The fan is spinning, I just didn't notice because of the low speed. I also noticed that the line leaving the condenser has a slighty cool feeling to it. So I evacuated the system and put straight RedTek in only to find that is doing the same thing. It will drop the air temperature out of the vents by 2 degC.

I don't think my system is as far gone as yours was. That's rough!

Also the refrigerant never leaked out completely, I suspected it may have been low on charge but there shouldn't be any leaks in the system. I'm now wondering if maybe the compressor is weak.

I'm in Saskatchewan, close to Saskatoon.

[jtanguay]

the sanden a/c compressor is a pretty tough compressor... mine was left open to the elements and still blows cold air.

you should change the receiver drier for sure.  how many cans did you put in?  jetta's take around 2 cans, and passats take around 2.5 cans.

if the high side is getting hot, then that means that the a/c compressor is doing its job.  i would inspect the condensor to see how badly it is caked with dirt etc.   when i removed mine, the rad was loaded with dirt and debris.. $80 or so for a new condensor! highly worth it.  just remember that if you can't remove the heat from the condensor, then the system will not work correctly.