air conditioning help

I know there was a tread a couple days ago about his, cause I did the search. but I didnt know if my situation was any different, or if I could get mor input, so please help me out.

it has been 80+ now for a while, and when trying to use my air conditioning it seems as if it is jsut blowing out slighlty cool (and this is on max with the gauge all the way to the coldest). Ive let it run for a while and it doesnt cool anything down. Im just curious as to a possible diagnosis. I dont think its a hose leak, cause when it is cooler outside, it seems to work alright. and I've heard about the kits you can get with a hose, adapter and can of R134A and I was wondering if someone could explain that kit a little more and how it might help me.

Thanks a lot guys!

Chris

ucilxj said:

I know there was a tread a couple days ago about his, cause I did the search. but I didnt know if my situation was any different, or if I could get mor input, so please help me out.

it has been 80+ now for a while, and when trying to use my air conditioning it seems as if it is jsut blowing out slighlty cool (and this is on max with the gauge all the way to the coldest). Ive let it run for a while and it doesnt cool anything down. Im just curious as to a possible diagnosis. I dont think its a hose leak, cause when it is cooler outside, it seems to work alright. and I've heard about the kits you can get with a hose, adapter and can of R134A and I was wondering if someone could explain that kit a little more and how it might help me.

Thanks a lot guys!

Chris

Click to expand...

For starters, what year is your XJ?

my bad. . didnt see I left that out. . .its a 91

umm low coolant level
my advise is sont change the system charge it
converting a sytem isnt a good thing yoiu start peg where pog and yoiu start having problems
not sure but I believe that the evaporator is larger on r134a sytems wich wouldnt let the coolant work to its max potential

what I did and this a bit more work is
go online
get your epa cert
get some r12 off ebay and do it yourself
you can get some manifolds and other tools to help the fix


but the cheaper way is to convert

maybe someone will chime in who has done a conversion
now I am carefull not to let any gas out cause that would hurt the ozone layerand the fine is more than I could afford to pay
even though some homes being built use r12 in thier systems

Block-off 1/2 air-flow in front of the condensor/radiator with cardboard and check if the vents blow colder. Don't idle too long and watch your engine temp but if it cools better with less "capacity" it's surely low on charge. The next hurdle is to figure-out if you're already running R134 or older R-12?

Service fittings are much different on R-134 and converted systems.

I'm having a similar problem, I turn the AC on max with the slider at it's coldest and all I get is hot air and doesn't cool at all. I noticed that when the AC is turned on the front plate on the compressor does not engage(stays still then spins for a while is what normally should be happening, right?) and I was told by the previous owner that the AC needed recharged, should I go ahead and get a can of AC coolant from Wal-Mart and try refilling it or could this be the AC compressor clutch?

1990 XJ Pioneer 2 Door 4.0

I've got a 90 and a 94 XJ. Both have a sight glass on the top of the receiver, (black canister below the compressor). Follow the outlet of the condenser and it should lead your right to it. The sight glass is very small. With the air conditioning system running use a flash light and look at this glass. If you see it flashing (bubbles in the glass), chances are you are low on refrigerant. There are other causes of bubbles in a sight glass, (not condensing due to poor air flow across the condenser, non-condensables in the system, so without the proper equipment to diagnose the problem this is a S.W.A.G.)

Most likely both XJ's mentioned in this thread are low on charge. If they are low on charge, there is a leak because refrigerant does not just disappear. Look for signs of oil around A/C fittings etc. If you see a suspicious area, use dish soap in a little water. If the fitting is leaking, it will bubble up.
Hope this helps.

Just recharged mine on my 99 Tuesday. Now i know thats possibly completely different from yours, but my symptoms were cool versus cold air, even on max and 4, and the compressor was cycling on and off alot while sitting at idle. Hooked up a guage to it (can't remember the name of it...the special ones for hooking up to a/c compressors) and all the pressures and everything checked out good. Since there's no real way (that I know of) to know how much freon you actually have with out tearing everything apart, we just guesstimated and added a small can of r134 into it...like 10 oz. I actually have a/c again...lol.

If you can hear the compressor and electric fan cycling on and off alot while sitting idle and running the a/c, it's probably jsut low.

Zoro said:

I'm having a similar problem, I turn the AC on max with the slider at it's coldest and all I get is hot air and doesn't cool at all. I noticed that when the AC is turned on the front plate on the compressor does not engage(stays still then spins for a while is what normally should be happening, right?) and I was told by the previous owner that the AC needed recharged, should I go ahead and get a can of AC coolant from Wal-Mart and try refilling it or could this be the AC compressor clutch?

1990 XJ Pioneer 2 Door 4.0

Click to expand...

At least you looked for the compressor clutch engaging. There's a pressure switch in the filter/dryer/sight-glass contraption behind & below the compressor. This will prevent the clutch from engaging the compressor if system charge is too low. Freon carries the lube oil in the system so it can't spin for long with little Freon.

However, there is probably a leak and until you qualify how much of a leak, you will never be able to tell if the system will hold for very long. R-12 is pretty expensive to find that out. R-134 is another matter and I've ran a parking-lot converted system for nearly 5 years with no problems.

If you decide to convert, the pressure switch can be jumpered to turn the compressor and with the high-side open and suction port closed it will basically evacuate itself in a matter of minutes. Close-off the high-port and add R134 oil charge into the suction side. Next, add 2 cans of R134 and check the sight glass. A few bubbles are fine and R134 seems to work best in an old R12 if the system is slightly undercharged.

Did you know that a Freon vehicle system cools the interior by way of the air in front of the radiator? How is that if the air is 100F degrees and right next to a 200F degree radiator? Well, due to the latent heat value of Freon, cooling down that Freon in front of the radiator by merely 4F degrees will be converted into a 30-40 degree temperature drop once the pressure/temperature of that Freon drops in the evaporator box where the fan moves the cold air into your vents. Sorta like a transmission/gear ratio thing is how I look at it.

Freon pressure is proportional to temperature. You can know the pressure in any part of the system if you know the temperature and vice-versa. A cheap dial thermometer can be used just as effectively as pressure gauges attatched to service ports if you use a little ingenuity to measure temperature. I suppose one of those infra-red temp guns would be a great AC tool but I've never tried one of those yet? I usually duct-tape a cheapo dial-thermometer to my lines and stick one in the vent when I wish to see the "ratio" that any Freon system is operating.

Blocking-off airflow across the condensor is another way of manipulating "ratio" and a way I use in conjunction with a vent thermometer to tell if a system is close to proper charge.

I took a look at my AC System again today with the motor running, the Compressor Clutch still didn't budge so I'm guessing what you're saying is right about the low pressure. I also noticed that one of the little hoses that is part of the AC system looks like it bursted, the outer jacket of the hose is peeled back for about an inch and I can see the inner part of the hose from the cut. I'm guessing that this is where the leak is coming from, does that sound about right? I also wiped the dust off of the viewing glass and used a flash-light to look into it with the motor running and I could not see anything at all, just looked like an eye staring right back at me...

How hard would it be to convert my system to R134 and how can I tell if it's been converted already?

well, for my 91, I ran the air with the motor running. I had the slide on the coldest with it on max air. I know that I have an r-12 compressor or whatever, but I am still not sure what I am supposed to look for. the only thing that I noticed was a strong vibration when the air is turned on. and like the question above, how hard is it to change to an r-134 system? if I take my xj to a dealership, what do I have them do?

How did you determine which side is the high port and low port?

S = Suction, low pressure
D = Discharge, high pressure.

You'll usually see these two letters cast into the compressor body near the ports. I've also seen caps which were marked "H" and "L", and since the two fittings are different sizes, they wouldn't go on wrong way around.

I've done the conversion a couple times - it's doable, but you have to have the system evacuated (tell them you're doing the conversion and they'll flush it as well to clear the lines) then you'll need to change the Receiver/Drier and install adapters for the service fittings (which come as part of a kit.) Do that, take it back in, and tell them you need the system evacuated again (pulled to vacuum) and you can then recharge it with R134a yourself with gages you can get at your local.

Considering R12 is (around here, anyhow) now upwards of $100 per pound, you can come out ahead pretty damn quick this way. I'll be doing a few more of these conversions (restomodding an 89 and an 88) while I'm replacing compressors and such over the next year or so...

It's really not that difficult to do, if you know one end of a wrench from the other. I think it took me about two hour's work all up, and probably an hour at the shop (I'm friendly with a number of local shops that I send business to...)

5-90

99XJSPORT06 said:

Just recharged mine on my 99 Tuesday. Now i know thats possibly completely different from yours, but my symptoms were cool versus cold air, even on max and 4, and the compressor was cycling on and off alot while sitting at idle. Hooked up a guage to it (can't remember the name of it...the special ones for hooking up to a/c compressors) and all the pressures and everything checked out good. Since there's no real way (that I know of) to know how much freon you actually have with out tearing everything apart, we just guesstimated and added a small can of r134 into it...like 10 oz. I actually have a/c again...lol.

If you can hear the compressor and electric fan cycling on and off alot while sitting idle and running the a/c, it's probably jsut low.

Click to expand...

Be aware that jeeps used some pretty crummy evaporators in the heater boxes from 97 on, they normally leak on XJ,'s TJ's, ZJ's. They replace alot of them at around $700 a pop, 8 hours labor to totally remove the dash to get at the heater box. Next time you add 134a use the kind with the dye in it then after a while look at the drip hose on the firewall just above the frame rail where the drain is, use a black light and goggles, look for a yellow stain and if it's there thats where your leak is, in the heate box.

Ok. I am a brand new user, so I am sorry if I get anything wrong. I have a 2000 stock XJ 4.0. I am having a similar problem with my AC. First it takes forever to actually cool off when I am driving it and when it finally does start to cool, it is definitely not cooling as well as it should be. Details: system is charged, had a leak which has been fixed, and freon is not low. The electric fan does not come on when I turn the AC on, like it should, but it does turn on when the jeep gets hot. But even then, the air is just cool, not cold. Now, if I drive it at night or when it isn't hot outside, it cools just fine. I am almost 8 months pregnant in South Louisiana and I am dying without good AC, so if any of you guys feel the least bit sorry for me or Goodburbon, who has to listen to me whine about it all the time, I would appreciate any help you could give us. Thanks. =)

I find it interesting that the fan isn't coming on when you turn on the AC - it should. One of the conditions for turning on the AUX fan is getting an "AC REQ" (Air Conditioning REQuest) signal from the ECM - which makes me think that the signal isn't making it out of the selector switch. I'd have the other half start there. (Nothing disparaging meant - but mechanical skill or no, if you're 8 months along, I just don't see that you should be working on your vehicle right now... Isn't that why you married him anyhow? :kissyou: :repair: )

Anyhow, have him check to see if the AC Compressor Clutch engages when the Air Conditioning is turned on, as well as the aux fan. Since you get the fan when the temperature is up, that means the circuit proper is working - and one of the triggers isn't. If the AC Comp Clutch doesn't engage, I'd start with the ventilation controls.

5-90

Oh, I haven't been working on it. He has. And yes, that is why I married him =). He is just in class right now so I decided to post and see if you guys had any answers for our problem. I will pass this info on to him. Thanks

Ok the clutch is engaging, the low and high side pressures check right (40psi,and 300psi respectively). I am leaning toward the ECU not getting a signal, or not opening the relay. Is it the same relay fed by 2 different sources or does the ECU control everything?

I checked it all out for her and its not the relay, nor the charge, nor the dash switch, or even the fan itself. The fan does come on when the jeep gets too hot, but nothing when the compressor is engaged.

does this mean that she has a bad ECU?

Follow up.


it was not a bad ECU, apparently in 2000 model year cherokees the aux fan is not triggered unless the AC head pressure is high enough. even if its hot. I thought the dealer was FOS when he told me this, so I bought an FSM and sure enough, the circuit requires the head pressure sensor to close the circuit before activating the aux fan Relay.:lecture:

And her AC is leaking from the schrader valve. It will not stop, I have replaced it 3 times, and she continues to loose charge....I guess I'll have to get one of those $100 Manifold assemblies.:rattle: