Recharging the A/C

[televascular]

Is recharging the A/C system part of regular maintenance, or a remedy for a problem? How long does R134a last? I don't know jack about this stuff.

Approaching 50,000 miles, looking for ways to keep my hands occupied.

 

[duaneb9729]

Refrigerant does not wear out or go bad, it will leak out but if the system is cooling your car, i would leave it alone.

 

[-Clayton-]

No a A/C system doesn't consume refrigerant, The only time it will need refilled is if there is a leak or if the system has to be opened up for another problem. The only real preventative maintenance for a A/C system is to ensure that it's run regularly even through the winter so the seals don't dry up.

 

[mechtech2]

All systems leak. Teh average is 7 ounces/year, according to Ford. It leaks through the compressor seal, line seals, and right through the hoses.
Top it off every year with a kit with a can and gauge.

 

[Chris142]

I do not recomend that you try to recharge it w/o any knowlege of how the system works. At the least buy a book and a set of high and low pressure guages before you try anything.

 

[onion]

Originally Posted By: mechtech2
All systems leak. Teh average is 7 ounces/year, according to Ford. It leaks through the compressor seal, line seals, and right through the hoses.
Top it off every year with a kit with a can and gauge.


Um... don't do that. Bad idea.

A/C systems leak, and may need topping off on occasion. But even with a proper set of gauges AND a sight glass (which have been eliminated in most systems these days), you can only get a fair guestimate of whether or not an a/c system is fully charged. The ONLY way to know for sure is to recover the refrigerant and weigh it... which is a valid and fairly easy troubleshooting procedure if you have the right equipment.

IMO, if your a/c is cooling adequately, then it's a BAD idea to top it off. Over-charging can make the system cool less efficiently and is hard on the compressor.

If your system hasn't been charged or topped off in several years, AND it isn't cooling like it used to... then it might be worthwhile to add a can of refrigerant to see if that improves cooling. But just topping off regularly (when you've no way of knowing how much refrigerant is in the system) WILL cause problems.

 

[severach]

>All systems leak.

No they do not. Most systems leak because there are many parts in the system that are prone to damage or failure.

The most common failure is a stone strike to the condenser in front of the radiator. Since that and the rest of the failures are so expensive people end up adding refrigerant to get through the hot season. Improperly serviced systems are where the idea comes from that refrigerant must be replenished periodically.

Systems repaired properly will be leak free until the next failure occurs. A few vehicles with good luck and above average AC parts will remain leak free and require no service for the entire life of the vehicle.

>to recover the refrigerant and weigh it...
>if you have the right equipment.

We extract refrigerant with an empty propane bottle and a freezer. It takes about 4 hours. A vacuum pump is necessary to ensure the tank is clean.

 

[The Critic]

Don't worry about it unless there's a problem. If there is, take to a shop and have them evacuate the system and measure how much was removed, then recharge to the listed capacity in the manual.

Gauges and DIY cans are worthless, the only correct way of doing it is to take it to a shop and have it done.

 

[Merkava_4]

Get a meat thermometer and stick it in the air vent. If you're 40 degrees cooler inside than the outside, you're in good shape.

 

[BearZDefect]

Originally Posted By: Merkava_4
Get a meat thermometer and stick it in the air vent. If you're 40 degrees cooler inside than the outside, you're in good shape.
What fan speed for this test?
May I add that you should have the engine running at around 2,000rpm rather than idle to judge the AC performance?

 

[MrCritical]

I put the fan on the first or second speed, while driving the car. Use one of the center vents, and have the switch on recirculate.

 

[JHZR2]

My 98 chevy truck cools like day 1, never been touched.

Unless you really control your lines, every time you fill up, youll also introduce a bit of air and humidity.

There is a dryer to scavenge it, but the fewer times you have to open the system, the better.

There is no reason to have to add refrigerant at 50k. I have original systems that are 20+ years old and 220K+ miles on them... And window AC units that are 20 years old and still cool like champs...

There can be leakage, especially if the system isnt used regularly, as seals can dry out and then be more leak prone. We run our AC systems year round, nearly 100% of the time, and still beat EPA highway mileage, so if you drive right, it isnt that huge an efficiency killer.

Top it up if you sense it isnt cooling as good as normal. You can look at equilibrium pressure of a cold-soaked AC system (pressure vs. abmient temp charts exist) to ensure that your fill is nearly 100% correct. That might give you peace of mind.

But Id rather avoid opening or tapping the system unless I had need to do so.

JMH

 

[mechtech2]

All automotive AC systems leak - unless it is a sealed home system, expect leaks.
Ford's testing was accurate.
It is a GOOD idea to keep the refrigerant topped up.

 

[onion]

Ok, mechtech. For those folks around here who don't have access to a proper manifold gauge set, and a factory service manual that shows appropriate high and low side pressures for their specific vehicle according to a given ambient air temperature... how exactly do you propose that folks "keep the refrigerant topped up" without risking an over-charge situation?

A single cheap "can and a gauge" ain't gonna do the trick. People who try this without knowing what they're doing are going to end up with systems that do not cool properly... and possibly compressor failure.

Yes, a/c systems leak to some extent. But you can't count on 7 ounces per year. It may be more, may be less, may be danm near zero- depending on application. If the system is cooling properly, leave it alone.

 

[Merkava_4]

Originally Posted By: BearZDefect

May I add that you should have the engine running at around 2,000rpm rather than idle to judge the AC performance?


Yes ... I left that part out.

Fan speed on at half way between low and high for the first reading and at full speed for the second reading. On an 80-85 degree day, mine gets down to 40-41 degrees with the coldest reading on medium fan speed.

 

[BrianWC]

Originally Posted By: onion

A single cheap "can and a gauge" ain't gonna do the trick. People who try this without knowing what they're doing are going to end up with systems that do not cool properly... and possibly compressor failure.


Guilty.

Blew up my already volatile CR-V compressor once with that very method. Had about one gillion lbs of pressure on it.

 

[wantin150]

Tis the season for AC issues. Mine quit cooling the other day after I turned the car off and then on again about 5 min later (03 Matrix XRS). With the car running, I turned the fan switch off and then on again and the cool came back. Any ideas?

 

[mechtech2]

Cheap can and a gauge works great.
1/2 hour on the internet will get anyone enough advice.
It is a very simple procedure.
AC on Max, fan on high, windows open. Rev engine 1,500 to 2,00 RPM.
Let it stabilize for a minute.
Only read the gauge when the compressor clutch is engaged on a cycling system. It will read high when in an 'OFF' cycle.
Yawn... nothing to it.

 

[onion]

So you understand a/c systems. Good for you... so do I.

But most people don't. And they'll screw up their system by following your advice.

 

[Schmoe]

If it ain't broke, don't fix it.