A/C quit working

OK my 95's A/C was working fine about two months ago...since then it hasn't been driven a whole lot...once a week maybe...so now the A/C doesn't work.

The compressor and electric fan turn on like normal.....compressor doesn't cycle on and off strangely.....

Two things I've noticed....there is a funny noise coming from behind the dash whenever the a/c is on.....kinda like that trickling sound some a/c make after you shut off the engine....like pressure is bleeding off but it does it all the time now.

I also noticed when I turn the a/c off and go to vent that the flow of air through the vents somes and goes....like the air door is opening and closing randomly....

Any thoughts...

THanks,

Chris

The climate control dampers are operated by use of vacuum....; so if they dont operate properly... neither will the A/C.
Does your vehicle have cruise control? If so... does it still work properly?There could be a vacuum leak in one of the lines....
The most common place for vacuum leaks is beneath the battery tray due to acid eating thru the tubing....., but since you heard a hissing sound behind the dash....; I would suggest you start your search for a vacuum leak there....

You have a vacuum leak in the dash. Follow the sound to the leak source and fix the leak.

OK small vacuum leak found and fixed....now all the doors operate like they are supposed to and air flow is constant but the evaporator inside the a/c inside the cab is not getting very cold.
The lines under the hood leading into the back of the dash are cool to the touch, not super cold but cold.... Compressor is really hot, as is the line leading back to the accumulater below the compressor, I mean burn your hand kinda hot. Still hear a funny sound coming form the unit inside the cab under the dash....could something be plugged and not letting the refrigerent get into the evaporator? or is the system just low on refrigerent? Should the two lines leading into the dash be a lot colder?

(Edited after I read up on the parts of the system....)

Also disconnected the vacuum line feeding the whole system and I can still hear the hissing sound under the dash..so I think I am hearing the noise from the eveporator.....don't remember hearing this noise while it was running when the a/c was working....only right after you shut off the engine, now I hear it anytime the a/c is on and the compressor is pumping.



Thanks Chris

According to a Jeep technician that I know.... he said that XJs are known to have problems with evaporator that spring leaks in the coil...
When you say the lines are cool....; could you give me a guess as to what temperature they might be....
I am guess there is a slow leak in the evaporator coil under the dash...
If you have access to gauges... you might want to check to see what the pressures are and have the charge checked....

CharlesS said:

According to a Jeep technician that I know.... he said that XJs are known to have problems with evaporator that spring leaks in the coil...
When you say the lines are cool....; could you give me a guess as to what temperature they might be....
I am guess there is a slow leak in the evaporator coil under the dash...
If you have access to gauges... you might want to check to see what the pressures are and have the charge checked....

Click to expand...

Thanks. The lines are mabye 50 or 60 degrees....cold to the touch but not so cold that I can't hold on to them...maybe as cold as a soda coming out of the fridge.

I'll see if I can find a set of guages from one of my buddies and see what the pressure is. Any idea what pressure I should be seeing?

Thaks again,

Chris

OK just checked the same refridgerent lines on my work truck and they are freezing cold....so looks like I'll start with a re-charge and go from there. Haynes manual says to check the "site glass" and if it looks foamy then the refridgerent is low.....not sure if it looked foamy but it definitely looked different than either of our other cars.

Thanks for the help so far.

Chris

The '95 uses R134a as a refrigerant... If the temperature of the low pressure line is only 50-60*; then it definitely is low on refrigerant...
The line pressure should be approximately 38-45 psi (42-50*) LOW and 180-240 psi (123-143*) HI. These readings may fluctuate some depending upon outside air temperatures....
The sight glass should only have a couple bubbles going thru it occasionally....
The factory system only holds 1.5 lbs (a little more than 1 can) of refrigerant so be careful if you decide to add some yourself....

16 oz (weight) per lb, so that is only 24 oz, or (2) 12 oz cans???? Is that REALLY all they used in 95???? I do recall reading that they decreased the amount used, but that seems pretty low.

Also my 87, now converted to an R-134a, holds 85% of the original R-12 charge, which comes out 38 oz (a hair over 3 cans). Also, I have read that the low side (at least for the 87 running R-134a) is 20-40, and the high side is 170 - 200 psig. Are they running the newer OEM R-134-a systems at higher pressures than the converted R-12s????

CharlesS said:

The '95 uses R134a as a refrigerant... If the temperature of the low pressure line is only 50-60*; then it definitely is low on refrigerant...
The line pressure should be approximately 38-45 psi (42-50*) LOW and 180-240 psi (123-143*) HI. These readings may fluctuate some depending upon outside air temperatures....
The sight glass should only have a couple bubbles going thru it occasionally....
The factory system only holds 1.5 lbs (a little more than 1 can) of refrigerant so be careful if you decide to add some yourself....

Click to expand...

CharlesS said:

The '95 uses R134a as a refrigerant... If the temperature of the low pressure line is only 50-60*; then it definitely is low on refrigerant...
The line pressure should be approximately 38-45 psi (42-50*) LOW and 180-240 psi (123-143*) HI. These readings may fluctuate some depending upon outside air temperatures....
The sight glass should only have a couple bubbles going thru it occasionally....
The factory system only holds 1.5 lbs (a little more than 1 can) of refrigerant so be careful if you decide to add some yourself....

Click to expand...

Thanks for the info. My father in law has the guages and we are going to take a shot at it tomorrow. Definitely see lots of bubbles in the site glass, so hopefully that's it....if there is a small leak at least I'll know in a couple of weeks.

Thanks again for all the help,

Chris

Ecomike said:

16 oz (weight) per lb, so that is only 24 oz, or (2) 12 oz cans???? Is that REALLY all they used in 95???? I do recall reading that they decreased the amount used, but that seems pretty low.

Also my 87, now converted to an R-134a, holds 85% of the original R-12 charge, which comes out 38 oz (a hair over 3 cans). Also, I have read that the low side (at least for the 87 running R-134a) is 20-40, and the high side is 170 - 200 psig. Are they running the newer OEM R-134-a systems at higher pressures than the converted R-12s????

Click to expand...

In my '98 the factory recommends a weighed in charge of 1.5 lbs of R-134a.
That is why I recommended approximately 1 can; since his system already has refrigerant in it. The only way to charge the system correctly is by weighing in the charge to an evacuated system or charging it by superheat....; usually 12-14*.

Not all cans are 12oz by weight.... There are others that are 16oz.; which is what I use....
IIRC.... the older systems held more refrigerant. The evaporator and condensors were also larger....