AC Use / Problems in Winter

[xxandrewnxx]

It's a brisk 35 degrees when I was out and noted this oddity with my AC.

Hopped into the the Patriot today with the wife for a quick trip to the store; her usual self, she flips it from vent to defrost before the vehicle is on. I strap in the kiddo and she starts the Jeep with the defrost in the on position. I'm only reinforcing this because I did not hear the RPMs drop or hear the compressor kick on. The air did smell ... conditioned[?]

As we leave the store, the position is still on defrost [I think]. Jeep wouldn't start ... just cranks. Any way, I stop cranking, back off the key, try again ... Jeep starts after a few cranks. Temps have been fluctuating a lot; didn't let the Jeep get very warm; short trip ... vapor lock? Could be anything. Who cares, it started.

So, we get home and I pop the hood to give it a quick visual inspection of anything loose, anything making noise. I ask her to turn it off of defrost. No difference. I don't hear the AC click off, no quick drop and pick up of the RPM. I ask her to put it on vent and hit the AC button on. Again, brief change of RPM, no click of the compressor turning on. And so now I'm getting worried there is a problem with the system, especially because we're only about a month or so away from 90 degree temps and a little one in the back seat.

I'm fairly certain the AC was working last week in the defrost position, as I almost clearly remember a puddle of condensation under the Jeep.

Is it something with the ECM or something that regulates differently when the compressor will kick on during colder temps? Does it sense for humidity level before running when in the feet/defrost or defrost position? Or will it work 100 percent normal just like it does in the summer months?

Thanks in advance!

[dixiedawg]

As far as I know the A/C does kick on for defrost, but I can't remember details.

[xxandrewnxx]

Thanks for the look! Yeah, I'm sure it runs while on any position using defrost. I think my question was confusing.

I know I won't hear the compressor click or notice any draw off the battery or minor rpm drop if the vehicle starts with the compressor on. What has me worried is that with defrost on and in the regular vent position, I'm not noticing a draw or drop or hearing the compressor when turning on the ac either.

I know I won't see a condensation puddle because its frosty out and the it would seem unlikely to be exchaning heat/creating condensation.

Is there any reason why the compressor would be engaged and I wouldn't notice a voltage draw or minor fluxtuation in rpm? It seems so normal in the summer, I'm missing it now and am worried something is broken!

[Afmcronnie]

Im not an a/c expert, but I think its a staged system. Something in the valving. In the defrost position, with the temp control set to heat, it operates to remove moisture. If the condensor is already cold enough, the compressor may not need to run all the time.

[Tater1800]

Is the compressor turning all the time? Some of what you said makes me think about the A/C clutch. This would cause it to feel like it wasn't working since there is very little loading in cold weather.

The clutch connects the compressor to the drive belt. If everything in the chain moves the clutch is locked. It should cycle on and off and allow the compressor to stop.

[goguadi]

Originally Posted by Afmcronnie

Im not an a/c expert, but I think its a staged system. Something in the valving. In the defrost position, with the temp control set to heat, it operates to remove moisture. If the condensor is already cold enough, the compressor may not need to run all the time.

+1

[xxandrewnxx]

Originally Posted by Afmcronnie

Im not an a/c expert, but I think its a staged system. Something in the valving. In the defrost position, with the temp control set to heat, it operates to remove moisture. If the condensor is already cold enough, the compressor may not need to run all the time.

Thanks! This makes me feel a little better ... I'm not an A/C expert either, but this does seem, to me, the logical way it would operate and the reason I'm not experiencing the same function in the colder months.

With an infant and the expenses that come with her, it's just easier for me to be proactively paranoid and plan for the worst, but I really think I need to settle down and wait this one out until it's a more clear whether there is a problem or not.

There is nothing visually mechanically seized, and there is nothing indicating there is a potential issue — squeaks, smells, miscellaneous shenanigans....

Appreciate the help ... I'll save my panicking for next month when we bounce back to 90 degree temps.

[The_Jeep_Life]

I have noticed that my a/c will come on if I have the controls set to auto, I have the climate control.

[Metaxa]

I think it probably is coming on for you in defrost and just to be certain why not set it to max cold and AC...feel the air from the vents.

The only thing (not talking to mechanical stuff broken) that might be happening is a low refrigerant level...that is an easy thing to check.

If your R134 is low make sure the place you get to recharge the system puts in tracer dye so you can see any leaks...often you can tighten them down yourself.

And one last, general tidbit, for everyone:
Automotive air conditioning is definitely a use it or lose it item. There are lubricants and cleaners in the refrigerant as well and they must circulate to keep things clean, lubed and working. If you have air run it...letting it sit idle causes more issues than the minor fuel savings. Use it year round, you can heat with air conditioned air. I make sure to use air at least one day per week on my 200+/- km work day.

[JoeP]

Originally Posted by Metaxa

I think it probably is coming on for you in defrost and just to be certain why not set it to max cold and AC...feel the air from the vents.

The only thing (not talking to mechanical stuff broken) that might be happening is a low refrigerant level...that is an easy thing to check.

If your R134 is low make sure the place you get to recharge the system puts in tracer dye so you can see any leaks...often you can tighten them down yourself.

And one last, general tidbit, for everyone:
Automotive air conditioning is definitely a use it or lose it item. There are lubricants and cleaners in the refrigerant as well and they must circulate to keep things clean, lubed and working. If you have air run it...letting it sit idle causes more issues than the minor fuel savings. Use it year round, you can heat with air conditioned air. I make sure to use air at least one day per week on my 200+/- km work day.

Yes and no.

Yes, put the air con on and check if the air coming out is colder than the air going in.

No, a loss or refrigerant is not the only thing that might be happening, and checking the level is only an easy thing if you have the equipment and expertise to do it.

No, the reason why the system should be run occasionally is to prevent the seal on the compressor from drying out. The refrigerant doesn't contain cleaners, the refrigerant is itself a cleaner, and as long as the system is tight, the inside will not suffer during a prolonged period of not being used.

And one last, general tidbit, for everyone:
The dye in general use fluoresces under uv, so if you want to take advantage of dye in your system, use a black light to inspect.

[Metaxa]

Well, excuse me!

Allow me to re-phrase:
The refrigerant is formulated to act as both a cleaner and lubricant as well as refrigerant so run your AC on occasion.

And Joe, up here in the cold north country every second garage has an AC machine, costs in and around $50 CAN to get checked out. So I'd say its an easy thing to check.
Did you miss the part about excluding "mechanical stuff broken"? If the AC seems to not work under cold operation the next logical step is to check the refrigerant level. If that checks out fine then you must start the significantly more expensive diagnosis of mechanical parts.

Go have a cup of coffee and settle down, eh?

[Arthur]

Originally Posted by xxandrewnxx

Hopped into the the Patriot today with the wife for a quick trip to the store; her usual self, she flips it from vent to defrost before the vehicle is on. I strap in the kiddo...

I know you're looking for answers but this line made me LOL from personal experience.

[dixiedawg]

We have a rule, My Jeep, I handle the controls, her Truck, she handles it. The tracker, whoever is driving handles the controls.

[JoeP]

Originally Posted by Metaxa

Well, excuse me!

Allow me to re-phrase:
The refrigerant is formulated to act as both a cleaner and lubricant as well as refrigerant so run your AC on occasion.

No. That is not true. It just so happens that the refrigerant is an effective cleaner, it does not carry out that function by design. Also, the refrigerant does not lubricate, there is oil in the system to do that.

And Joe, up here in the cold north country every second garage has an AC machine, costs in and around $50 CAN to get checked out. So I'd say its an easy thing to check.

Following that logic, every check possible is an easy check.

Did you miss the part about excluding "mechanical stuff broken"?

No.

If the AC seems to not work under cold operation the next logical step is to check the refrigerant level.

Only, that's not what they check. They check the pressure in the system, which will show if the system is completely devoid of refrigerant, but will not give you a level. The only way most people could tell you for sure what the level is would be by removing the charge and weighing it.

If that checks out fine then you must start the significantly more expensive diagnosis of mechanical parts.

Again, not the case. If the refrigerant charge has gone, it has obviously gone somewhere, so it is pointless (not to mention against the Kyoto protocol) to add refrigerant to a system with a known leak. So if you find that the refrigerant is gone, then begins the task of finding and rectifying the leak (potentially quite expensive). A decent refrigeration engineer wouldn't just dive in and remove the charge without doing some simple diagnosis first, and attempting to diagnose the fault, and the remedy to most faults is likely to cost little more than renewing the refrigerant charge. Trouble is, when every second garage has some bloke who knows how to check the pressures and renew the charge but little else, you end up paying over the odds to get them to do more than that.

Go have a cup of coffee and settle down, eh?

I'm quite chilled thanks, but as you're offering, black please, no sugar. And bring me some of your gateau too

[xxandrewnxx]

In Raleigh yesterday, we went from upper 20s to upper 70s. Makes me miss Southwestern PA [a little bit] where 50 degree swings are not as common.

I did run the A/C as a test before opting for windows down. Everything seems to be functioning properly; got cold, no oddities, dripping condensate.

The other night — about 40 degrees — I did turn A/C to max and felt a temperature difference without noticing if the compressor was working, and did not have a thermometer to check for a proper temperature drop. I thought of it as a false-positive because of the cold.

But it would point to Afmcronnie's suggestion being accurate. It's logical for ambient/system/control temperatures and vent setting to determine operation. On vehicles without climate control, it's not switching from drying in a heat setting to conditioning on a cool setting to maintain a set comfort zone; it's all or nothing.

The wife — from my tuner Civic to my Charger to my Jeep — is always pushing my buttons.

Thanks for helping out, everybody!