AC not working

Jpd686 · **Joined:** Tue May 30, 2017 12:14 pm **Posts:** 50

Hello all, 05 liberty crd. AC does not seem to be working, I turn it on and it sounds like compressor is trying to turn on but isn't actually turning on. I can turn the center by hand very easily so it's not seized. Any tips? Checked the fuses and relays and they are all fine. It's a very hard sound to explain but it happens every 10-15 seconds and when I take the ac relay or fuse out it stops making the sound of it trying to turn on?? From what I read it's either a bad clutch, or low pressure. Any easy ways to test this?

Billybob · **Posted:** Mon Jun 26, 2017 6:21 am

Best to take it to an aircon shop and have it checked out....probably low on refrigerant so the Low Refrigerant Switch on the Jeep is not allowing the compressor to turn on. They can put a dye into the fill to show up any leaks.

WWDiesel · **Posted:** Mon Jun 26, 2017 1:46 pm

Sounds like freon low pressure switch is cutting AC compressor clutch on & off! When freon charge get too low, low pressure side pressure will drop below LP switch setpoint and stop compressor.
If pressure is right at LP switch's setpoint it will cycle AC compressor clutch on & off continuously which is not good for compressor clutch! :roll:

Best bet: Purchase a can of freon charge from an auto parts store that has the leak detector dye in it and add it to your AC system. This should stop the clutch from cycling by increasing the LP side pressure, and if you have any leaks, you should be able to find it with the dye in the freon... :wink:

If it is real low, you may have to add more than one can of freon.

papaindigo · **Posted:** Mon Jun 26, 2017 2:09 pm

I don't completely disagree with WW but remember this is an R-134a system not the old style R-12 and that normally to charge a 134a system all the coolant is evacuated; a vacuum is pulled; the system is recharged with coolant, by weight, and lube. Just adding 134a with dye from a can won't "fix" your problem in the long term but it might stop the cycling and ID the leak. Unless you are an AC tech I suspect a shop is in your future.

For those that know more than me - could it be a bad low pressure switch and if so can it be replaced without "opening" the system?

mrhemi · **Joined:** Tue Dec 08, 2015 10:46 am **Posts:** 180

I have had 2 2006 Liberty's that did this. Pressure check showed static charge of sufficient Freon but the compressor would not cycle. First step at this point is to place a jumper across the Freon pressure switch. If the compressor starts, check the system pressures. If normal, or near normal, the switch is bad. A new one is about $24 from Rock Auto as I recall. The switch can be changed without evacuating and recharging the system. It is designed to do so. I would not let an A/C shop at it until you have to.

Bushman5 · **Joined:** Sat Jul 11, 2015 11:05 am **Posts:** 276

Why is it so bad to let an AC shop refill these jeeps ac units? Wouldn't that be the best place to have it looked at?

mrhemi · **Joined:** Tue Dec 08, 2015 10:46 am **Posts:** 180

The A/C shop will be expensive. Most of them would drain it first, pull vacuum and recharge, more expense. The check and repair I described is easy to perform and inexpensive. The point I am making is a faulty switch can display the symptoms of low Freon. This is very easy to verify yourself, with little expense. Some HVAC repair shops can be quite unscrupulous, so I am just offering some buyer beware advice. If your system actually is low on Freon, the you will be dealing with a shop to find and repair the leak. The FSM has a procedure to test the switch.

WWDiesel · **Posted:** Mon Jun 26, 2017 9:06 pm

papaindigo wrote:

normally to charge a 134a system all the coolant is evacuated; a vacuum is pulled; the system is recharged with coolant, by weight, and lube. Just adding 134a with dye from a can won't "fix" your problem in the long term but it might stop the cycling and ID the leak. Unless you are an AC tech I suspect a shop is in your future.

Not true! I have topped off hundreds of 134A systems just by adding enough freon to get high side and low side pressures up to correct pressures!
A tiny, tiny seepage leak may require you to add freon every year, or every two or three years! I have seen them all!

I do pull a vacuum on a system that has been fully discharged or exposed to atmosphere. Pulling a vacuum evacuates all the moisture out of the system and makes it easier to fill.

Long before they had machines to remove freon, weigh it, and install the proper amount, it was all done with a vacuum pump and proper AC gauges and can still be done that way if you know what you are doing! Not everyone can afford a $2,000 dollar AC machine!

You can buy nowadays in the parts stores a 134A freon charge can that has a gauge on it for do-it-yourselfers, they work fairly good as long as you follow the instructions even if are not experienced at adding freon. Most system need ~25-40 psig on the low pressure side to be fully charged and satisfy the LP switch, and the low pressure freon line should be cold to the touch all the way back to the AC compressor when fully charged.

As others have stated, if adding freon does not make the compressor engage, the the LP switch is most likely bad. The LP switch connector can be jumped out to test the function of the LP switch.
But in all my years working on vehicles, in most all cases when you encounter an AC compressor clutch cycling in & out in some repeated secession, the problem is low freon! The LP switch is doing what it is supposed to do when this happens to protect the compressor! If the LP switch goes bad it usually fails completely in my experience!

If you are not comfortable performing the adding of freon operation yourself, find a friend who has done it and let them help you. It's not rocket science! This is a piece of cake compared to changing a timing belt!!! :roll:

Or if you want to spend $100 bucks or better, take it to a qualified shop that performs AC work, it's your vehicle and your choice! :juggle:

Bushman5 · **Joined:** Sat Jul 11, 2015 11:05 am **Posts:** 276

mrhemi wrote:

The A/C shop will be expensive. Most of them would drain it first, pull vacuum and recharge, more expense. The check and repair I described is easy to perform and inexpensive. The point I am making is a faulty switch can display the symptoms of low Freon. This is very easy to verify yourself, with little expense. Some HVAC repair shops can be quite unscrupulous, so I am just offering some buyer beware advice. If your system actually is low on Freon, the you will be dealing with a shop to find and repair the leak. The FSM has a procedure to test the switch.

ah thank you.

Jpd686 · **Joined:** Tue May 30, 2017 12:14 pm **Posts:** 50

Ok so I jumped the two wire sensor close to the fire wall. It started making the sound continuously but the inside of compressor was not spinning. Also the low pressure line got ice cold but the other lines do not. If my assumption is correct that would mean my AC compressor clutch is shot correct??

Can anyone recommend a replacement clutch or do I have to buy a whole new unit?

Billybob · **Posted:** Tue Jun 27, 2017 2:21 am

Jpd686 wrote:

Ok so I jumped the two wire sensor close to the fire wall. It started making the sound continuously but the inside of compressor was not spinning. Also the low pressure line got ice cold but the other lines do not. If my assumption is correct that would mean my AC compressor clutch is shot correct??

Can anyone recommend a replacement clutch or do I have to buy a whole new unit?

Not good to override the Low Refrigerant Switch for too long....running a dry compressor can very soon damage it.

You can remove the AC relay from the relay/fuse box under the hood to stop aircon from coming on at all and if the center of the compressor is not turning then probably you jumpered the wrong wires or the relay is faulty.

You can remove the AC relay and briefly jumper female pins 30 and 87 inside the relay socket to see if the clutch engages and the compressor spins....that will prove that your clutch is OK but probably low on refrigerant. :wink:

flash7210 · **Posted:** Tue Jun 27, 2017 8:49 am

Jpd686 wrote:

Ok so I jumped the two wire sensor close to the fire wall. It started making the sound continuously but the inside of compressor was not spinning. Also the low pressure line got ice cold but the other lines do not. If my assumption is correct that would mean my AC compressor clutch is shot correct??

Can anyone recommend a replacement clutch or do I have to buy a whole new unit?

If the low pressure line got ice cold, then the compressor was functioning.

When the compressor is compressing the freon, the high pressure line will get hot.
The purpose of the condenser (in front of the radiator) it to cool the pressurized freon so it can condense into a liquid.
When the compressed freon escapes through the expansion valve (at the evaporator), it de-compresses (changes from liquid into gas) into the low pressure line and gets cold.
This is the fundamental process of all air conditioning systems.

Jpd686 · **Joined:** Tue May 30, 2017 12:14 pm **Posts:** 50

ok ill try jump the relay under hood and see if i can get it to spin. so the general consensus is that im low on freon?

Should the compressor not have span though when i jumped the low pressure line though? or is there another sensor on the unit that wont turn it on unless there is enough freon?

Also, my vents inside the truck did not get cold when i jumped the LP switch, is this because the compressor wheel was not spinning?

tjkj2002 · **Posted:** Tue Jun 27, 2017 11:54 am

mrhemi wrote:

The A/C shop will be expensive. Most of them would drain it first, pull vacuum and recharge, more expense. The check and repair I described is easy to perform and inexpensive. The point I am making is a faulty switch can display the symptoms of low Freon. This is very easy to verify yourself, with little expense. Some HVAC repair shops can be quite unscrupulous, so I am just offering some buyer beware advice. If your system actually is low on Freon, the you will be dealing with a shop to find and repair the leak. The FSM has a procedure to test the switch.

Most places are running specials right now to see how much R134A your actually low and find the leak if there is one for $10-$50.

tjkj2002 · **Posted:** Tue Jun 27, 2017 12:04 pm

WWDiesel wrote:

papaindigo wrote:

normally to charge a 134a system all the coolant is evacuated; a vacuum is pulled; the system is recharged with coolant, by weight, and lube. Just adding 134a with dye from a can won't "fix" your problem in the long term but it might stop the cycling and ID the leak. Unless you are an AC tech I suspect a shop is in your future.

Not true! I have topped off hundreds of 134A systems just by adding enough freon to get high side and low side pressures up to correct pressures!
A tiny, tiny seepage leak may require you to add freon every year, or every two or three years! I have seen them all!

I do pull a vacuum on a system that has been fully discharged or exposed to atmosphere. Pulling a vacuum evacuates all the moisture out of the system and makes it easier to fill.

Long before they had machines to remove freon, weigh it, and install the proper amount, it was all done with a vacuum pump and proper AC gauges and can still be done that way if you know what you are doing! Not everyone can afford a $2,000 dollar AC machine!

You can buy nowadays in the parts stores a 134A freon charge can that has a gauge on it for do-it-yourselfers, they work fairly good as long as you follow the instructions even if are not experienced at adding freon. Most system need ~25-40 psig on the low pressure side to be fully charged and satisfy the LP switch, and the low pressure freon line should be cold to the touch all the way back to the AC compressor when fully charged.

As others have stated, if adding freon does not make the compressor engage, the the LP switch is most likely bad. The LP switch connector can be jumped out to test the function of the LP switch.
But in all my years working on vehicles, in most all cases when you encounter an AC compressor clutch cycling in & out in some repeated secession, the problem is low freon! The LP switch is doing what it is supposed to do when this happens to protect the compressor! If the LP switch goes bad it usually fails completely in my experience!

If you are not comfortable performing the adding of freon operation yourself, find a friend who has done it and let them help you. It's not rocket science! This is a piece of cake compared to changing a timing belt!!! :roll:

Or if you want to spend $100 bucks or better, take it to a qualified shop that performs AC work, it's your vehicle and your choice! :juggle:

R134A AC systems are filled by specific weight,not pressure.If you don't know how much is in the system you can't possibly now how much to put in.

R134A is nothing like R12,freon is a dupont trademark name for there R12 by the way.R134A will leak out at about 0.25 oz per year on a 100% sealed(IE no leaks) system since R134A molecules are much smaller then R12's and will bleed through the rubber hoses,no way to stop that.By the way all newer vehicles(last 20 or so years) have come with UV dye in the AC systems from the factory already since the high fail rate of R134A systems.

Plus most of those "DIY" kits at parts stores have stop leak in them and you do not want that stuff in your AC system,that is a $2000-$3000 repair bill since the entire AC system has to be replaced when you add that junk into it.

Without the proper tools and training you will do more harm then good.Just adding some R134A in is the worst idea ever and you need to know more then just the low pressure sides psi to actually figure out what's going on in the system,not to mention there are simple tests to determine if it's a electrical issue,mechanical issue,or a leak(low R134A).

geordi · **Posted:** Tue Jun 27, 2017 12:10 pm

Jpd686 wrote:

ok ill try jump the relay under hood and see if i can get it to spin. so the general consensus is that im low on freon?

Should the compressor not have span though when i jumped the low pressure line though? or is there another sensor on the unit that wont turn it on unless there is enough freon?

Also, my vents inside the truck did not get cold when i jumped the LP switch, is this because the compressor wheel was not spinning?

First things first - the AC compressor is at the BOTTOM of the engine on the driver's side, not the top on the passenger side. That is the viscous heater and has the same kind of clutch. Perhaps you were looking at the wrong unit?

If the lines got cold when you jumped the sensor, then the compressor IS running, but you probably do not have enough refrigerant in the system to make sure it is cold enough. Tiny leaks happen, this is somewhat normal to have to top it off once in a long while. You need to know the pressure, get a can that has a gauge (it will say on the can / gauge whether you can check the pressure without using the can) and see what the low-side pressure is WHEN RUNNING. If it is less than 25, you need more refrigerant, use the can. If it is above 25 when running (or jumped) then replace the switch. But from what you describe, I think the switch is fine, you need more refrigerant.

Don't overfill it, start with one 12 ounce can of just R134a (just refrigerant) and not the cans that have "leak sealer" or cans with oil as well - you likely don't need any more oil, and that will just take the place of refrigerant and reduce your system capacity.

Jpd686 · **Joined:** Tue May 30, 2017 12:14 pm **Posts:** 50

Wow I have been looking at the wrong system bahaha. I feel like an idiot. I tried jumping the one under fuse panel in the engine compartment. Same thing happens when I jumped the LP line, sounded like compressor came on and the LP line got cold.

So next is to check the freon level and hopefully fill it and get my system working again!!

I will also confirm that the compressor is actually turning on by jumping it one more time and check that the compressor wheel is actually spinning haha.

Jpd686 · **Joined:** Tue May 30, 2017 12:14 pm **Posts:** 50

https://m.canadiantire.ca/products/prod ... ku=0146129

Will this product work?? Says for 134 and for 12 systems....?

WWDiesel · **Posted:** Tue Jun 27, 2017 1:10 pm

Jpd686 wrote:

http://www.canadiantire.ca/en/pdp/red-t ... 46129.html
Will this product work?? Says for 134 and for 12 systems....?

Yes, looks like that should work just fine!

Be sure and follow all instructions and wear safety glasses anytime you are working on freon systems! :wink:

geordi · **Posted:** Tue Jun 27, 2017 1:43 pm

Yes, that should work fine to check the pressure, and that kind of gauge / can tap will also allow you to use any can of gas, not just the one / two that it comes with.

You may need to have the can on the tap (with the needle fully retracted) just to act as a seal on that end of the hose. There should be a one-way valve in the adapter, but just in case. The filling is not quite as precise as someone above likes to say it is - he works for a chain place that loses money when people DIY. Measuring the pressure from both the high and low sides is the precise way to know it is full and working properly if you aren't fully evacuating the system, but the high side also varies with outside temperature, so you CAN properly gauge the fill with only the low side number that this gauge will give you.

Also - the system has both a high pressure and a low pressure cut-out for protection, so you aren't going to do much of anything other than waste some cash if you screw it up somehow. But this is an easy fix. Once you know the pressure, I'm sure you will find that with the compressor on, the low side is somewhere around 0-15 psi, which is give-or-take about a 12 ounce can low. You can look at the sticker on the front crossmember to know for certain, but I believe the "full" charge of this vehicle is 1.5 lbs, or 24 ounces. Just look at the specific can contents, you want only Tetrafluoroethane (the refrigerant) in whatever number of ounces the can says it is - no oil, no leak stop. You CAN GET cans that are only refrigerant - I'm also partial to the "Arctic Freeze" line of products by Interdynamics. Here in Florida, whatever blend they are using in this can does seem to provide better performance than regular 134a, which is itself a blend of chemicals.

https://shop.advanceautoparts.com/p/interdynamics-arctic-freeze-ultra-synthetic-r-134a-refrigerant-19-oz.-af-6/10055040-P?navigationPath=L1*14922%7CL2*15020

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