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A/C Problem

26K views 9 replies 7 participants last post by  Hey12 
#1 ·
I recently purchased a 09 commander everything was working great till about a week ago. The a/c is blowing hot it was cold before not freezing but cold and then it just switched. I thought it was the knob and played with that and it got super hot then back to hot. The compressor is constantly on off on off. The rear a/c is blowing cold just fine. Has anyone had something lie this or know anybody who has and the solution please? I live in Florida and have two kids under 3 that ride with me and windows don't cut it any help is greatly appreciated
 
#2 ·
When you switch between on/off (from inside), do you hear the A/C compressor 'clutch' clicking as well. The compressor shouldn't be turning on/off by itself. Should coincide w/ whichever your internal control setting is at. Otherwise, could be a sign of a failing compressor.
 
#3 ·
Constant on off, on off of the compressor for a couple seconds at a time is usually low freon, but then the rear AC should also also be bad as it is just one system. I'd check the freon level first. They sell the freon recharge cans just about everywhere - in Florida they probably sell at every gas station:)
 
#4 · (Edited)
Just a nit-noid fact, in case if prevents any confusion while you try to fix this. "Freon" is a brand name for R-12 that is banned and no longer used, your Jeep uses R-134a for its refrigerant. It's like "Clean-Ex", "Q-Tip", "Kevlar", the popular brand name "Freon" gets misused as the name for a catagorie of product. So, use the words "refrigerant" or "R-134a" as you talk to techs or auto store folks so you don't create any confusion, or give someone with an attitude problem an excuse to look down on you.

When you say HOT? Do you mean the air is heated from the heater or just NOT cooled at all and it is the same temp as the outside air.

The environmental control units have small electric motor that turn plastic shafts to open "air blend" doors to direct the air, either over the AC evaporator and/or Heater Core and then out to different vents. So, if you have a good working AC system, the motors/shafts or doors of the "air blend" doors failing could cause it to blow hot or non-cooled air.

When the air blend doors fail, it "can" cause bad direction of air to the point it is NOT blowing or flowing from the vents you select or barely flowing from any vent even though the fan is whirring at full speed.

The Front and Rear AC/Heat are seperate units with their own doors, so one failing would NOT make the other fail.

BUT, you mentioned the compressor going constantly cycling between on/off, air blend doors don't cause this.

This is a classic symptom of being low on refrigerant. And the only way to be low on refrigerant is too have a leak.

My evaporator developed a leak, I've seen posts for other evaporators leaking on this forum (as well as air blend doors breaking), so it seems the front evaporator leaking is NOT uncommon on the Commander.

A leaking evaporator in the front would cause it NOT too cool (at least cool poorly) in the front, but the rear evaporator would still function while there was still some refrigerant left in the system (and the rear would get worse as the system leaked down).

Sorry, but to replace the Evaporator is a big job, the entire dash has to be pulled out. I just did it myself, it took all weekend, I'll have to post some pics I took. So, this is going to be an expensive repair to have a shop do it, NOT that the evaporator itself is cheap either.

One thing to keep in mind, AC oil. While the evaporator leaks, it will also leak out oil. If you keep recharging the AC with store bought cans R-134a, but NOT replacing the oil leaked out, you will run low on oil and that will cause your compressor to seize. That happened to me, and my AC repair got a whole lot more expensive.

The Commander's AC system uses ND-8 oil, which is the same as PAG iso 46 oil or PAG46.

The best thing to do is just get it repaired right away. You keep using the AC with a leaking evaporator, you're asking for trouble. But, if your going to keep recharging it with cans of R-134a yourself, then buy some cans of oil while you're at it and keep adding oil.

BTW, I Don't Know if your problem is really a leaking evaporator, from what you tell us, the symptoms sound like it, but I could be wrong, please take it to a shop and have them diagnose the problem for you.

A leak anywhere else in the system would cause both front and rear evaporators to perform equally poorly. The front expansion valve failing would cause the front to perform poorly while the rear performed better, and those parts can be replaced without tearing apart the dash, but you wouldn't have symptoms of being low on refrigerant.
 
#6 ·
A thermal expansion valve (TXV) "might" cause this problem, but I don't think it is likely, the TXV are the more reliable parts of the AC system.

The TXV throttles the amount of refrigerant going into the evaporator in response to how hot the refrigerant is coming out, i.e. keeps the evaporator at a constant temp as the heat load changes on it. A bad TXV could cause its corresponding evaporator to NOT cool, but the other evaporator that has its own good TXV would work fine. BUT, you wouldn't have a constantly cycling compressor, unless a stuck or clogged TXV is causing the hi side pressures to go so high the compressor is shutting down from over pressure.

The standard advice for all AC problems is too check the systems Hi/Low side pressures with true AC gauges (and do it per FSM instructions on the conditions and compare the figures against the tables in the FSM). That will truly tell you what is going on in your AC system, and you can make a far better diagnosis from there.

A leak will be obvious with the set of gauges.

A mismatch of pressures might NOT be obvious at first, but depending on the differences in pressures and other symptoms, a few troubleshooting steps to eliminate all the possible causes and narrow it down to a single cause, like the TXV.

From what little the OP has told us:
*Constantly cycling on/off Compressor with decreasing AC performance
-That is very likely low refrigerant charge, which means a leak

*Front AC evaporator performance is decreasing to the point it no longer works, while the rear AC evaporator perofrmance is much better.
-Throw in the number of posts about Commanders having a leaking front evaporator (including myself, which may be a bias on myself).
-This sounds like a leaking front evaporator

Again, the next step for the OP is too get a set of true AC gauges put on this system to properly diagnosis it, and find the problem. Either go to a professional shop, find a friend with the gauges and some AC experience or buy a set off ebay and then take a crash course in AC theory of operation and repair.

If it is a leaking front evaporator, this will be a job beyond most amateur mechanics to repair. (Don't get me wrong a good amateur can do it, I did it myself, but it is a big job that is a painful).

And one last re-warning about recharging the system yourself, especially if it is a leaking evaporator, you don't know how much oil you are loosing with the evaporator leak. I just recharge my AC several times, hoping to find the leak eventually, without adding oil, since I never found any leaking oil (it was deep inside the dash at the evaporator) so my AC system ran short of oil and seized the compressor and my repair than doubled in cost if NOT more.
 
#8 ·
Which one? The front or rear? Since you have problems with the Front AC, and the Rear works as expected, its a safe bet its the front one.

"got it checked" means you took it to a professional AC shop that did a full diagnosis?

A bad expansion valve could cause these symptoms. But expansion valves rarely fail, especially as drastically as would cause these symptoms, but it certainly is possible.

Did they confirm your AC system was fully charged and did NOT leak? The compressor turning on/off constantly is a symptom of low charge. It's possible the expansion valve is stuck closed and won't let refrigerant flow at all, that would "could" cause the compressor to cycle on/off constantly. If it was just the front expansion valve, then turning the rear AC on would cause the compressor to work normally and NOT cycle on/off constantly.

Condenser leaks are more common and it seems to be somewhat common in the Commander.

AFA changing it yourself, the difficult thing is de-servicing and properly servicing the AC system, you will need to replace the filter/drier as well, and service it with the proper amount of the right refrigerant oil for the parts removed and replaced. But the expansion valve itself is just a matter of removing one bolt, moving the lines out of the way (hard lines, so its NOT easy) and then two allen head bolts.
 
#9 ·
AC cutting off. Mine blows cold while driving at highway speeds. If you get stuck n traffic for long periods of time or park with the systems running, the AC cuts off for the rest of the day. Next day the AC works fine again.I'm thinking pressure switch but since it does not works fine at normal speeds not really convinced.Then i contact to AC Repair in Cypress for the detection of AC issue and the employee solve the problem.
 
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