A/C

[duke183]

So I know this has been beat to death but by searching I just became more confused. So WTH?

Last week I turned my A/C on to no avail. Only hot air blew out of the vents. However, it sounds like the compressor is working but no cold air. I have a recharge kit that I picked up at Advance Auto but after reading on here, does that seem like a good idea to use?

Is there any other thing I can look for to see if it just needs a recharge or if something is failing? Basically, I am looking for a smoking gun here.

Things just keep breaking or acting up on this thing. At least its paid off. Thanks guys.

Oh yeah 2000xj sport AUTO 96K

I got 134a

 

[winterbeater]

I am surprised that the compressor turns on. With my 2000, the compressor wouldn't even come on for me to feed it more "freon" without me jumping the low pressure switch. Double check to see that the AC line under the hood isn't getting frosty cold. If it is, you have some other problem with your heater doors or control. Don't be afraid to recharge with your "kit". I've used them often with usual success. My XJ though, only holds the freon in for a few minutes, so I gave up. Probably need to replace the evaporator. On other cars, I've used a can for a spring AC "tune-up" with success for many years.

 

[duke183]

Yeah nothing is cold, that is for sure.

 

[winterbeater]

Put your can in then. Once it starts to get empty, you can stick the bottom of the can in hot water to get the last stuff out. Just make sure to keep the can upright so that only gas goes in, not liquid.

 

[duke183]

Ok, good deal. I will give it a go. Thanks!

 

[ktwalker01]

Check a few things to really figure out what is going on.
1) see if the one of the leads going through the firewall from the condenser to the evaporator is cold
3) is it hot air like the vent is just blowing regular air, or HOT air like the heater is going
2) check the pressure for around 15-20 bucks you can get a reusable 134 fill tool and a can of 134a and on the reusable tool it will have a gauges that should show you the pressure of the system, to check that run the ac at MAX settings

If its blowing super hot air your heater door is more than likely stuck..

Did the A/C all the sudden just stop being cold? If so our 97+ models are prone to failure with the EVAP core. They are known to crack and cause a nice leak. Replacing it is super expensive to have it done professionaly because it involves a ton of labor, or you can buy a new evap core online for around 80-120 bucks depending on where you buy it. Replacing it isn't rocket science but its very labor intensive. It involves removing the ENTIRE dash board and steering column, and center console. I did it alone in about 6 hours.

If you charge the A/C and it works for only a day or few hours more than likely your evap core is busted, but to be safe i would buy a 134a with a dye in it to show where the leak is. And to know if it is the EVAP core you would see the dye in the drain plug in the firewall.

 

[APFPilot]

I've got a similar issue, nothing cold under the hood and the compressor keeps cycling, I bought a recharge kit and the pressure fluctuates when the compressor cycles. I'm not sure if it is okay to recharge?

 

[ktwalker01]

I've got a similar issue, nothing cold under the hood and the compressor keeps cycling, I bought a recharge kit and the pressure fluctuates when the compressor cycles. I'm not sure if it is okay to recharge?

Gotta get a gauge/universal fill tool and see whats going on. just throwing in a can could do more harm than good if it has enough pressure, or a leak (wasting 10 bucks on a can of 134a). Believe me its 15-20 bucks well spent for an older car.

 

[APFPilot]

Ok So I've got a gauge and it is connected to the low pressure port, what is ahppening is the pressure builds and once it reaches the high side the compressor clicks and the pressure drops...

 

[ktwalker01]

yeah, whats going on is when the pressure gets super low on the low side the compressor kicks off, and when the pressure goes up it kicks on. When its running the compressor is lowering the low side pressure because thats just how it works lol.

It heats the gas up and then the condeser flash cools it ( i guess) and the immediate low pressure is the cool gas that cools the air traveling through the evap.

Now if the pressure is to low on the low side the compressor wont click on at all (letting you know it needs a charge), to high and it wont turn off, nor cool properly.

When you do the test for pressure you should have the fan on hi and the setting on max ( generally the compressor will continue to run because at that setting it is working the ac at its maximum generally never allowing the pressure to get low enough to allow the compressor to cut out)

 

[ktwalker01]

also on the gauge you looking to be in the middle of the blue range.

 

[APFPilot]

so since it is bouncing then a recharge is in order? thanks for the help. It happens pretty quickly, at about a 5 second cycle.

 

[ktwalker01]

Yeah that usually means its due for a charge.

I remember recharging mine from none to full during the procedure it went from nothing to bouncing on and off really quickly to a steady run at pressure.

Like i said Max A/C setting with full fan the ac should keep the compressor running and the pressure should stay in the blue range

 

[APFPilot]

Awesome, it worked!!! Thanks again kt

 

[duke183]

Yeah I tried to check the pressure on the lower evap point, but I could not get a pressure reading or could I put any more chemical in there. I ran the ac at max for like 3-5 minutes before trying and I have not had anytime since to mess with it. I will try again soon after a couple of weeks. I just have no time, right now. I will use the info you guys gave me in hopes of figuring it out.

 

[UNCC_99XJ]

If you really want to see what's going on, invest in a set of full AC gauges. Harbor Freight by far has the best bang for the buck on these. They run $60 normally, but go on sale frequently during the spring summer months for about $45. Matter of fact, they were on sale this weekend when I was there. If you can get a hold of a 20% off coupon, you're down in the $30 range and they work just as good as other sets i've used, including snap-on. Having one of these allows you to look at both the high and the low side so you can see everything.

I've been getting more and more into AC work over the last couple of years, so a set of full gauges was a very wise investment for me.

Also keep your eyes out for a good vacuum pump...that way you can properly recharge the AC system (pull a vacuum for 20-30 minutes to get any moisture out, then recharge).