So it's hot as Hades today, I've got the AC cranked, and I hit the drive-thru for a cold beverage. I've got the window down, about to order when I hear a load bang followed by hissing. Sounded kinda like a tire blew out but then the steam started pouring out from under the hood. I turn it off, open the hood once it died down, expecting a blown rad hose or something. All looks good around the rad but I do see fluorescent green fluid by the firewall, around the AC condensation drain tube.
Thoughts? Is refrigerant similar in appearance to antifreeze? What blew up in the AC system? Did it blow and spew out the drain tube? Guessing I've got to tear some stuff apart to get a better look.

 

Coolant lines to heater core examine. Cracking or splitting.

 

Nope. If it's green, it's coolant. Like the man said, check those heater lines.

It's a 95, so it may have a heater control valve (HCV). If you are replacing those lines, this is a good time to get rid of it. Just cap the one vacuum line, disconnect from the heater hoses, and toss it in the nearest trash can.

One hose is 5/8", one is 3/4". Get about 4 feet of each, then cut to fit. Ordinary heater hose at your local NAPA or other parts store. OR, you can get the pre-shaped lines for later models (97+) that don't have the HCV. They will fit perfectly. Just more $$.

 

Could be UV dye in the AC refrigerant.

 

I am with agreen on this.
Looks more like dye then coolant.

 

the evaporator if blown, would spit green snot out the drain tube. Try the ac if it doesn't engage compressor then refrigerant is low due blown ac core . If the heater core blew then there would be residual coolant on the shelf.

 

I inspected again this morning, no obvious signs of leaky hoses or any damage for that matter. Checked the AC and no longer blows cold or engages. Pic I took was about 20 minutes after it happened and doesn't do it justice on how bright the fluid looked.
I'm convinced it's evaporator/condenser/AC line whatever is behind the firewall with the heater core....

 

Dang man. My condolences for your loss of AC.

Here's what you do. This is the least expensive way to repair it.

Step 1- Buy this kit. No, it's not top of the line anything, but for the hobbyist, it's perfect. I have industrial quality gauges, vacuum pump, etc, but my dad (a hobbyist) has this kit. He and I have done 3 cars with it and it's still working. It pays for itself the first time you use it too, so don't knock it.

Step 2- Determine where your leak is, and buy that component. Also get a new orifice tube (I think it's part of the high pressure line), a new receiver dryer, and maybe a can of system cleaner. I actually just use brake cleaner and a blow gun to flush any residual crap out of the lines, but you can get fancy if you want.

Step 3- Replace parts. The evaporator kinda sucks because you have to pull the dash, but that's the worst of it. Just keep telling yourself you'll be enjoying air conditioning soon. There's youtube videos out there about it.

Step 4- Use the vacuum pump, draw a vacuum on the system for at least an hour. There's people that argue that you have to vacuum for like 24 hours or something... sure.

Step 5- Charge the amount of refrigerant by weight. Start with the engine off. Make sure you purge ANY air out of the yellow line. Crack the line and keep letting air out until you get a cloud of refrigerant. There's a sticker under the hood that says how many ounces to put in. Once the first can stops going in, crank the engine, AC on max, engine idle. Keep charging to the low side until you get the number of ounces in.

Step 6- Check the pressures. Rule of thumb: low side pressure = the temp leaving the evaporator. About 35-45 psi (depending on how hot it is outside). The high pressure = 100# above current ambient temp, add up to 50# for humidity. If your numbers are close to that, call it.

If you have further questions, research some youtube videos on how to charge refrigerant. There's a lot of good info out there.

Again, this is the least expensive route. My brother's TJ needed a new condenser. Cost over $1200 at an independent shop. I could have done it for about $100.

 

If you replace A/C evaporator, you'll want to replace the heater core while you have the dash apart. I believe there is an aftermarket company that makes all metal heater cores for the XJ.

Was your XJ converted over to r134a refrigerant? Or was it still the r12 refrigerant? If it's r12, you'll most likely pay a pretty penny for the stuff.

FYI, you pull a vacuum on the system to get any impurities out of the system. Your system has now been exposed to atmospheric air, which contains oxygen, nitrogen, moisture, etc... You want to get that out of the system & put in freon. The impurities will corrode the a/c system from the inside out & also you could end up freezing up the inside of the new evaporator, because of the impurities.

 

Thanks for the info everyone! Yeah been doing a little research, it's got to be the Evaporator, cost is not too bad on rockauto. The procedure to change looks like a real PITA so I'll order and do the heater core too. Wish they'd open the border so I could order and pick up real cheap but what can you do.
As for the refrigerant...I don't believe it's been converted, and based on the colour, the web tells me it's not 134a. I'll look into the kit, (not available on Amazon at the moment), or talk to a shop about draining and filling after....

 

If you end up replacing the evaporator core and need to find more of that black foam that goes on the "downwind" side of the evaporator to keep the condensate from spraying everywhere, let me know. I have a bunch left over.

 

If it is a 1995, then the Evap core on rock auto is a little different than the factory one.
There is a Thermistor probe that actually goes into the factory evaporator. The newer style cores are different, and the probe (thermostat) will have to go on the outside of the core. This is less than ideal, as the fresh air comes over it there.
What I did was to add some Eastwood Strip Caulk made into a ball on the outside of the probe, to keep the incoming air off of it.
One more note!
You have to pull the probe out of the HVAC unit to R&R the evaporator. More than likely you will break it. They are no longer made, so look on fleebay for one first. There was a guy selling some that were not a "perfect match", but would work well if you can not find the factory one.


Old evap core on the left. Note the hole for the thermister.

 

Here is the listing for the AC thermostat on ebay : https://www.ebay.com/itm/26481784499...EAAOSwe7BWw7ND
If you do the heater core at the same time pony up for the copper core. I bought the aluminium one off of rock auto, and I have to replace it again before fall.