Well I've put this off as long as possible but today's +95* temp outside was killing me. Long story short my ZJ has had a small A/C refrigerant leak for the last 2 years, I usually had to recharge it once every 1.5-2 months during the hot months and once every 3-4 months during the non-summer months. I didn't get it fixed because when I initially took my truck in to have it checked out for the leak the repair shop stated that it was $600 to get it fixed, so I figured I could live with spending $15 bucks every couple a months to recharge the system because it was a very slow leak. Well during the winter and spring seasons this year I didn't maintain the system like an idiot and when I tried to use it today I was completely discharged and was just blowing air. My question is, is there anything in particular I need to do or need to recharge my system now since it is completely discharged or can I just buy one of those R134a Complete Service Kits with the refrigerant, oil charge, O-ring conditioner and maybe a couple extra cans of R134a to get my A/C up and running again? Also how many cans of R134a refrigerant does an A/C system on a Jeep 4.0L usually hold. I hope I didn't mess up my system by letting it discharge completely. ANY advice is appreciated. Thanks in adance.

Fred R.

The 134a replacement contains the oils already you need for your compressor. Just put the recharge in till the suction line gets cold and wet. As far as leaks, they only get worse. You'll find yourself having to recharge more and more often as the leaks get bigger. I am an hvacr service technician. That being said, they make a dye for residential and commercial a/c systems that you put in with the freon. After a few days of regular use, I go back and inspect system with an ultraviolet light. Wherever the leak is, the dye shows up bright yellow under uv light. I'm not sure if they make anything like this for autos, but it'd be worth some research. I've also heard of spaying everything with soap bubbles, while charging to find a leak. I would not recommend this. Because if the soap gets into the system where the leak is you can damage or even kill the compressor. It will also change the chemical compound of the freon your putting in. Resulting in compressor and valve damage or death. Hope it helps! <img src="/forums/images/graemlins/kewl.gif" alt="" />
P.S. not trying to be an a-hole, but to be politically correct, you should not keep recharging this without repairing the leak. Your grandkids aren't going to have any ozone layer left to keep the sun from melting them.

Every autoparts store I've been in lately has the freon with leak checking dye in it. <img src="/forums/images/graemlins/cheers.gif" alt="" />

do you know how it is detected? ex.-uv light. Just interested. I never work on auto a/c. My a/c is take off the doors and put the top down.

I kind of figured that all I needed was a recharge kit but I just wanted to make sure that there wasn't anything else. Thanks again for all the help.

Fred R.

Not really, I've never used it myself, just seen it on the shelf next to the regular 134a. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Well I bought one of those A/C Recharge kits and an extra can of refrigerant at Autozone and I only had to use the recharge kit on A/C system and now it works fine. I checked the pressure on the low-side service port and it was reading within norm compared to the ambient temp. I'll check again tomorrow during a different time of day to see if I get the same OK readings. But now I have another problem, my truck is overheating. I did a radiator flush and put in new antifreeze/water mixture and it still overheats. It's not the fan as I did the Ford Taurus e-fan swap a few months ago and cleaned the radiator fins while I was at it and the fan is still working fine. The radiator was gushing antifreeze from the radiator cap so I bought a new one (18lbs) same as the stocker and it worked fine for the most part until I would gun it and then the truck would overheat and now it's spilling antifreeze from the cap again but not as much as before and ONLY about 1-2 minutes after I turn off the truck. It's never done this before, so I think whatever was wrong running the A/C put it over the top. Does anyone know what this could be? Engine runs strong, just passed emissions 2 days ago so I know it's not running rich which would cause it to overheat, no blown head gasket, so I'm thinking one of two things... I've been running the wrong cap all this time like an idiot and it's not holding the proper pressure OR the thermostat is sticking. I'm going to swap out the thermostat tomorrow for another unit just incase but I have another question. Should I get one with the stock temp of 195*, or should I get a 180* or even a 160* thermostat. I know with the lower temp thermostats it allows the engine to run cooler but is there any downside to running a 160* thermostat? Thanks in advance. It's a 97 4.0L by the way and I replaced the radiator last year...


Fred R.

Your 97 is an OBDII vehicle. A thermostat witha lower temperature wil likely set a code and turn on the MIL. If you really think the thermostat is sticking closed, by all means replace it, but use the factory temperature.

Double check to make sure the fan really is working on the fastest speed it can. Perhaps when you set it up it wouldn't work on high speed and you never noticed.

If you haven't ever replaced your radiator cap, do it now. They do wear out.

Lastly, and most importantly, are you sure it's overheating? What is the temerature of the coolant when it starts spewing? What does the temp gauge say is going on?

Howdy Fred Always use the factory temp thermostat! Period!
From your description I'm guessing you do NOT have the overflow hooked up to a container.. If it only spits out a small amount of coolant that is prolly normal. When the engine is turned off there is sometimes a squirt of coolant into the catch can. then as the engine cools down the coolant from the can is sucked back into the engine.
The reason for the can is to keep AIR out of the engine. AIR causes rust to occur in the engine. If you do not have one go shopping.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

52degrees, yeah I was planning on replaceing the thermostat when I get out of work today, just wanted to see if it could be anything else that I might have missed. Also the fan is working, it is a 2-speed fan and I have the switch in the cab where I can turn it on low, off or high, and it is overheating with the fan on high high setting. I also replaced the cap as that is how I lost most of the fluid when it first started overheating, I replaced it with a similar 18 lbs unit which is the same as the stocker and the guy at the auto parts store said it was the correct one. I know it overheating because my truck normally sits at 210* but the temp slowly climbs up until it is sitting in the 230-240 range. I don't continue driving it until it hits the 260 red zone cause I don't want to blow a head gasket and most of my driving is to and from work 5 miles away. I'm thinking it is the thermostat sticking shut because normally the truck gets up to about the 210* range then I can see the needle go down about 10+ degrees when the thermostat opens, and now it is going right past 210 and right into the 230-240 range.

BigJim I do have the overflow tank hooked up and the reason it is spilling from the cap 1-2 minutes after I turn off the truck is that the overflow tank fills up and then it starts spilling from the cap slowly but it's not gushing as it was before with the old cap. I am at a complete loss here, hopefully a new thermostat with will fix it. On a good note my A/C is working perfectly though <img src="/forums/images/graemlins/smile.gif" alt="" />...

Fred R.