a/c spontaneously quits

Hey guys... 94 jeep cherokee. Flipped on a/c a few weeks ago and absolutely nothing... no attempt at a/c clutch engagement, and also no electrical fan engagement. I swapped the relay with a known working one but that wasn't the issue. The electric fan still works as it should... comes on at about 215 and also switches on if I unplug the temp sensor. I searched around on here but it seems as if almost all problems are either related to a lack of cold air, noisy compressor, leaks, etc. The a/c has always worked fine in the past. I will admit I know very little about a/c in general; I have a stupid Chilton's manual but they give zero information about anything related to the air conditioning system. Compressor won't turn on with defroster either; based on what I've noticed, it would seem to be an electrical issue; I used to engage the electric fan before I changed radiators by quickly moving the hvac lever from bi-level back to vent; I moved it back to the vent setting before the compressor could engage, but the e-fan would stay engage for awhile.

Hopefully I'm missing something obvious; any ideas as to what may be causing this? The weather is starting to heat up... thanks!

On a 1994....it should be R-134a freon, but i'm not sure exactly what year they switched to it on the XJ's (it was around this time for most other vehicles).

If you've checked all fuses/relays and they check out good, I would go with it being low on freon. There is a low pressure cut off switch that's designed to keep the compressor from coming on when the freon level gets too low, to prevent damage to the compressor.

If it takes R-134a (there will be a sitcker near the belt routing diagram sticker that tells you what type it takes, and how much) you can go to just about anywhere and get a can, as well as the equipment to fill it up. All the equipment consists of is a hose with one fitting to fit onto the freon can, and the other onto the low pressure side of the a/c lines (and it'll only fit on one side, so no worries about filling the wrong side). The guages are on these types of hoses aren't the most accurate, but it's certainly better than paying big bucks for the professional set.

To add, turn the engine on, the a/c to max (recirculate) and the fan on high, and simply fill until the level is good. The compressor may or may not kick on when you start adding. If it doesn't, you'll need to jump the low pressure cut off switch to make the compressor come on.

Hope that helps you some.

Thanks for the reply UNCC; unfortunately (and I should have mentioned this in my original post) my system is R12. I thought about the possibility that the system was low on refrigerant, but it always worked fine up until it just quit, and the compressor never cycled faster than normal. I'm hoping I didn't develop a large leak for some reason. I was reading about the conversion kits (which doesn't seem too hard)... also that 12A refrigerant that's supposed to be compatible with R12. Perhaps I'll just take it to the shop to have the level checked and if necessary the remaining R12 evacuated, and then convert it myself.

Do you by some chance know that if the compressor is keeping itself from turning on, does the e-fan also not turn on? Just asking because mine always turned on the second I switched the control to a/c, even before the compressor engaged; and now it doesn't do that.

Thanks again.

The low pressure cut off switch would prevent it from turning on if you're below the pressure threshold. If you follow the wire from the ac clutch, you'll find where it connects to the main harness. You can split it here and then apply 12v directly to the clutch to make sure the compressor's working. Do NOT do this for long or you may burn up your compressor.

If you decide to convert, make sure they reclaim any remaining r-12, flush the system to remove any old oil and pull a vacuum to make sure it's all clean inside and there are no leaks.

AH, one more thing. Assuming there are no leaks, you can still buy R-12 on eBay. eBay rules say you have to be either certified or provide a statement saying it's only for resale. I think the resale statement is BS but it seems to be the way most people go (FYI I'm certified).

Thanks Saudade. I looked around on ebay and found an abundant supply of r12... along with a bunch of other shady looking kits. It looks like I can find cans of r12 relatively cheap, along with oil. Does anyone have a r12 recharge kit they recommend? A lot of the ones on there didn't have gauges and it seems like that would be important to have.

I'm sure this answer is on here somewhere, but does anyone know off the top of their head the refrigerant capacity of the 94' r12 system? I'm at work right now and can't pop the hood but I'm trying to get an idea of how much I will need/$ to spend. I realize I'm getting a bit ahead of myself here as well, but if I were to recharge with R12, is there a ratio of new oil to add along with the new refrigerant? I assume the oil cans use the same fittings as the r12 cans.

A/C System R-12 Refrigerant Capacity
1989-90 .......................................... 36-40 Ozs.
1991-93
Cherokee 2-Door ................................... 32 Ozs.
Cherokee 4-Door ................................... 38 Ozs.
1994 (up to 12/93)
Cherokee 2-Door ................................... 32 Ozs.
Cherokee 4-Door ................................... 38 Ozs.

pauldo39 said:

Do you by some chance know that if the compressor is keeping itself from turning on, does the e-fan also not turn on? Just asking because mine always turned on the second I switched the control to a/c, even before the compressor engaged; and now it doesn't do that.

Thanks again.

Click to expand...

Correct. If the A/C compressor doesn't kick on, the fan won't either. However, the fan should still come on when the engine temperature gets high enough. If it doesn't, then you also have a problem with the fan.

Thanks for the answers guys. Saudade, being a/c certified, do you have a ballpark estimate of cost a typical auto shop would charge to do your aforementioned suggested steps (reclaiming remaining r12, flushing out, pulling a vacuum)? Apparently r12 itself cannot be shipped to Wisconsin, so that rules out that option.

If the initial cleaning stage isn't too expensive, based on what I've looked at the conversion to r134 doesn't seem hard at all.

search a/c problem (intermittent)

Can you tap on the front of the compressor while the engine is running
and hear it engage? Could be the air gap on the compressor, which was my
problem. I'm not a big fan of a/c guys, seems to be a lot of them that want to replace parts (spendy part$) rather than diagnosing and correcting the issue.

just my $.02

Good luck !

2001 XJ Sport
Bone Stock

pauldo39 said:

If the initial cleaning stage isn't too expensive, based on what I've looked at the conversion to r134 doesn't seem hard at all.

Click to expand...

My cert really only allows me to purchase R-12. I've always done all of my own servicing so I can't tell you how much a local shop to you would charge. Call around to several and get quotes. Who said you can't get R-12?

Saudade said:

Who said you can't get R-12?

Click to expand...

I noticed on a couple of eBay seller websites they all mentioned "Sorry, cannot ship to Wisconsin". I messaged a few of them and they both said that there is a restriction on selling to Wisconsin addresses, so I checked it out.

Refrigerant Sales To Wisconsin Customers; The "State of Wisconsin" prohibits the sale of refrigerant in containers holding less than 15 pounds, (section 100.45 Wis. Stats. and Chapter ATCP 136 Wis. Adm. Code) and restricts end-use of other refrigerant sales to businesses registered with the Wisconsin Department of Agriculture, Trade and Consumer Protection or the Wisconsin Department of Commerce for servicing air conditioning and refrigeration systems.

So it's dilemma time over here. It actually looks like I can't order any refrigerant.

Wow!! Do you see any R-134a on the shelves at autoparts stores?

Wow Again! Never mind.....
http://datcp.state.wi.us/trade/regulation/trade/refrigerants/index.jsp

Refrigerant sales in Wisconsin are restricted to licensed businesses. This applies to all refrigerants including R-134a, the common replacement refrigerant used in motor vehicle air conditioning viewed as non-ozone depleting.

The sale of small containers of refrigerant (containers holding less than 15 pounds) is also prohibited in Wisconsin. These are container sizes generally marketed to the do-it-yourselfer who are generally not trained nor equipped to properly service vehicle air conditioning and trailer refrigeration systems.

Actually, even though it seems like you simply can't buy any small quantity of refrigerant, I just checked the stock at a local Advance Auto parts and it clearly states I can order now and pick up in store 12oz cans of r134a. I haven't seen ANY of this stuff for myself so hopefully this Friday I will go see for myself.

I guess my ignorance on this matter speaks a lot for the a/c system in the jeep. It is almost 15 years old and the a/c has NEVER been serviced, never been recharged, nothing; and has worked flawlessly up until this point, which it was still blowing cold and running fine. That I guess would partially explain my complete lack of Wisconsin law regarding this!

I appreciate everyone's input on this... I intend to get a low pressure side r12 gauge and check the level to see if the lack of freon is causing the compressor to keep itself from turning on; I also need to jump the clutch and see if that still works fine. If I'm lucky I'm hoping I won't have to actually deal with getting my hands on refrigerant if its unrelated.

Alright, so an update... I jumped the low pressure switch and the a/c worked perfectly fine, so unless the sensor itself is bad (which I doubt) then obviously the r12 level is low. At least it's narrowed down. Now comes the part of figuring out how to get some r12 up here. If my a/c system is leaking, it has to be an incredibly slow leak, as it took 15 years to reach a level that kept it from turning on. Now that I think about it, the air wasn't that cold anymore before it quit so that just seems reasonable.

Hopefully I can figure out a way to get r12!

Well, you could try bidding on auctions that don't have the WI restriction posted. I just charged mine up with R-12 and watched a whole bunch of auctions close before bidding to see what was the going price. I never saw one that specifically mentioned WI.

You could also have them sent to a friend or relative out of state and have them reship. In the end, it may be cheaper to convert to R-134a.

I don't mean to hijack this thread, but I'm experiencing the EXACT same thing. So how hard is it to use those 'do it yourself' a/c refillers... ? How much do I put in? And what type of gas to I use in a 98 xj sport?

A 98 should be R-134a. You can grab a can at Walmart with the connector for like $10. Just add the whole thing. If its low enough to stop running it's at least 1-can low. I think total fill is around 24-ounces or two cans.

Do you really need the a/c all that much in Chilliwack?

lawsoncl said:

A 98 should be R-134a. You can grab a can at Walmart with the connector for like $10. Just add the whole thing. If its low enough to stop running it's at least 1-can low. I think total fill is around 24-ounces or two cans.

Do you really need the a/c all that much in Chilliwack?

Click to expand...

Yeah it cuts out after about 5 mins of running, then kicks back in about 20 mins later.

yeah we need A/C up here, we're lookin at 25celcius (google for in farenheit), then within a month it'll be in the 30's.