QuestionChris-
You seem to be the man to talk to about A/C...
My 98 Jeep Cherokee's air conditioning isn't cooling.
I recently recharged it along with the added leak stopper.
I noticed then that is wasn't super cold like it was last summer. Well as I'm using it more, I notice that air is less cold and the engine fan (or compressor, right?) kicks on and off every 5 seconds when the A/C is on. Thoughts?
AnswerHi Zach,
Hmmm.... normally, when the system short-cycles, it's one of two things: a low charge, or an over charge. R-134 systems are very picky about having the proper amount to be efficient, which is why all shops have Recovery, Evac and Recharge machines at their disposal. With older systems, like R-12, you had a bit of wiggle room, and some even had sight-glasses you could see by (some still use them).
What was the cause for recharge? A repair? A/C systems are sealed, and require little-to-no internal maintenance. Some folks like to 'top it off', but that leads to issues later on. You mentioned leak stopper? I have to caution you against this stuff, since it tends to cause more trouble than it's worth (gums up compressors, etc.). Most of these are fluorocarbon resins, transported by system oil (PAG), that react to oxygen in the air, and seal small leaks -- in theory it's great, but they are often hit and miss. I'd refrain from adding anything that didn't originally come in the system. Some of these stoppers include a dye that can be used to check for leaks with a blacklight, so if you have a small leak, you might be able to pinpoint it.
If there was no clutch engagement before you charged, than chances are you might have a leak that the stopper can't stop. If the system was empty, than there may not be enough R-134a to prevent the low-pressure switch from opening the circuit, preventing the compressor from damage. Conversely, if the system wasn't empty, it may be overcharged, and unable to stay below the hi-pressure switch.
Sometimes, your hands and eyes can clue you in, too. The high side of the system -- from the compressor discharge, through the condenser, and to the fixed orifice (built-in to the liquid line), should be HOT. After the orifice (the line is generally dimpled where it lies inside), the piping should be COLD, although much less so AFTER the evaporator (compressor inlet). Anything outside of this is abnormal (when the system is RUNNING), and can lead you in the proper direction, provided you have one important tool: a gauge set. The simple gauge that comes with some DIY charge cans is not enough to properly diagnose the system. Particularly with your problem, you need to know if the high side is too high, or the low side is too low, or any combination, especially when a restriction can cause similar problems as well.
Another thing to check is the radiator fan -- is it spinning up when the compressor is engaged? The PCM turns on the fan when it receives an A/C request signal. If it's not running, that will surely cause decreased A/C performance, mostly at idle. You had stated that the something kicks on every five seconds, and I assumed it was the clutch -- but if it's the fan, than it may be just following the clutch cycling.
I love DIY repairs, don't get me wrong. However, if you don't have the proper tools, sometimes it costs you more money than just having a certified shop take a look at it. You might even start with getting it properly recovered, evacuated and recharged, and then see where the system is at -- often times, especially when overcharged, the price is reasonable because you don't have to pay for refrigerant. Whatever the case.... good luck!
