Recharging A/C

[Married2Allis]

I used a recharge canister on the wife's 2013 Town and Country. So easy a cavemen can do it. Followed instructions to the letter but pressure only made it up to 10 PSI and needs to get up to 40 PSI. Is it common to need 2 cans to recharge or is there maybe something else going on? The compressor kicks in fine and the pressure has held for several days.

 

[kcm.MN]

If your system was really low (which is probably why you noticed it), then there's a good chance it'll need part of another small can. Yes, I like these refill cannisters also, especially how you can re-use the hose on other cans, which means you can get the lower-priced cans without the hose from now on.......providing you don't forget where you put said hose, like I have! :lol:

 

[jacksun65]

Different vehicles take different amounts, even same vehicle may take different amount.

 

[JMOR]

(quoted from post at 08:43:35 07/31/17) I used a recharge canister on the wife's 2013 Town and Country. So easy a cavemen can do it. Followed instructions to the letter but pressure only made it up to 10 PSI and needs to get up to 40 PSI. Is it common to need 2 cans to recharge or is there maybe something else going on? The compressor kicks in fine and the pressure has held for several days.

here is usually a sticker near radiator support that specifies the amount needed to fully charge the system. "It held for 10 days".......well, it looks like it took 4 years to leak down to this point.

 

[Bob]

Working on an AC system without having basic data at hand is probably NOT a good idea. Can you find the AC data tag (EXAMPLE shown below) under the hood somewhere?

<img src = "https://lh3.googleusercontent.com/UsochCMtJ791JqefSLuAEf7CKCZzMLSAPJYhltBRjcgMlLO-gQhHxOoXFftpoNPi7UpU8GNaMNbxNQ=w800-no">

Even with that info, you won't know exactly how much it takes unless it's been totally evacuated.

That being said, your system likely holds somewhere between 30 and 50 oz (the higher # with rear air), so one 12 oz can isn't gonna do it if the system was nearly MT.

If you decide to add more, proceed with caution, it's easy to find a lot of basic AC charging info on the 'net as to what to watch for.

Too much will result in extreme high-side pressure and possible compressor damage if unevaporated liquid refrigerant enters the suction side of the compressor.

 

[dzc3]

Get a meat thermometer stick in in the vent when on Max AC and fan on high. This will "help" tell you if have added enough Freon. Should be in the 50 degree range.

 

[Married2Allis]

Thanks for the info Bob. Exactly what I'm looking for. Although ...

(quoted from post at 06:04:14 07/31/17) Working on an AC system without having basic data at hand is probably NOT a good idea.

If I didn't have a basic idea of what I was doing I wouldn't be cautious about the next step ... adding more refrigerant. I've done this before on other vehicles with success. I asked the question because I didn't realize there was a sticker showing the capacity. I only have 500 other things going on at the same time. Are you a professional mechanic?

(quoted from post at 06:04:14 07/31/17)
Too much will result in extreme high-side pressure and possible compressor damage if unevaporated liquid refrigerant enters the suction side of the compressor.

Exactly what I'm worried about. Thanks.

 

[Roger Tomfohrde]

Been working with refrigerants both in autos, residential and commercial since 2000. Best to know what the other port or high side is doing if you add more, usually there is a limit switch around 275 to 300
there. 40 psig seems a bit high as most systems operate around 25.Once you go higher in pressure the evaporating temp also rises and cooling ability is lost. I use a book that lists most cars and trucks but
is getting old. Tractors usually have a sight glass but I do not trust that completely also. If it keeps up on a hot day leave it alone is my best advice. I agree with the 50 degree temp posted before. As
usual check the coils for cleanliness as it will change pressures in a heartbeat and when checking temp the fan is on high.

 

[Bob]

I am certified under EPA Section 609, (easy) and EPA Section 608 as a "Universal Technician" (a bit tougher).

 

[Married2Allis]

Thanks for the professional advice Rodger. Maybe I can add more to get to about 25 lbs and see where I am. Don't want to blow the high side.

 

[El Hombre]

(quoted from post at 14:32:35 07/31/17) Get a meat thermometer stick in in the vent when on Max AC and fan on high. This will "help" tell you if have added enough Freon. Should be in the 50 degree range.

Actually if the fan is on low, it gives the air a little more time to dump the heat into the evaporator. That was how I was instructed at trade school. Middle vent duct, that one is the closest to the evap and will be the coldest. The vents at the end of the dash would run hotter.

Usually runs a couple of degrees colder on low. I was always shooting for high 30's pressure on low gauge; that meant the evap was running about 34-37 degrees and was staying just above freezing.

That was a good as that system was going to run....

 

[BobReeves]

Use the thermometer in a vent, add till the temperature is no longer dropping then quit. A cheap remote digital sitting on the dash works well, you can see the display from under the hood.

Fast idle, use something to hold it a little above idle, all windows closed, fan full on recirculate on.

 

[Geo-TH,In]

It's been a long time since I charged a car AC, so
not sure if a site glass is still on newer cars. The
site glass is on top of the filter dryer. When you
have a full charge, liquid Freon should be present
in the filter dryer and the site glass will be
clear, full of liquid. If you are low on Freon,
there will be air bubbles in glass.

The filter dryer is cylinder shaped. Has tow pipes
connected to it. One pipe is connected to the
condenser, the other pipe goes to the evaporator.

Report back of if you have a site glass and does it
have air bubbles or clear?

 

[GarryinNC]

A good rule of thumb is to slowly add more refrigerant until the suction line gets cold and 'sweaty' all the way back to the compressor. R-134 reaches 32f at about 20-21 psi. At that point the compressor should cut out to prevent the evaporator from freezing. If it was just low, you should be okay without a high side gauge. Charge it up and see how long it lasts before it needs more. We have a 2003 Town and Country. As others have said, better to under charge a little than to over charge.

Garry

 

[sotxbill]

Always taught.. fan on high.. set to outside air, all windows down and engine reved up above an idle.

You want to fully fill the system, so you want it to fully condense and evaporate.. so windows down and set to out side air.. Otherwise you will not charge it enough to get a full charge, and it will show prematurely charged under mild conditions...

its 105 today.. so much for prematurely charged.

 

[kevinthefixer]

One thing they hammered on when I took the certification course for 134A (it was new then). Do Not Try To Clear Up A Sight Glass! If you manage it, it will severely overcharge the system. Of course, they also said that you'd need the certification to buy the cold juice, but that seems to have been lost somewhere.

 

[tractorguy2]

How much you need to add all depends on how much has leaked out. On tractors and combines it's not uncommon for some to need two
or three cans.

 

[Geo-TH,In]

Why would there be a site glass if it wasn't used to
check Freon levels? Article says newer cars may not
have site glasses. The old cars R12 did and 134A was
a replacement for 12.
Article says there may be an occasional bubble. I was always taught if there are many bubbles and AC isn't cooling good sign you're low on freon. If you have too much freon, you may notice frost forming on compressor, liquid getting back to compressor.
using site glass.

 

[BobReeves]

Hasn't been sight glasses on cars since the 70's, at least none I have owned. Charging till the temperature quits dropping was a tip given to me by an old coot Chrysler dealer mechanic and it always worked for me.

 

[4play]

@ cans to recharge? Was the system empty and what size are the cans used? If the system was empty, it either takes 1.8lbs (28oz) for front air only, or 2.5lbs ( 40oz ) for front &amp; rear air.

Typical low side pressure varies from around 20-45psi, with compressor on.

 

[Married2Allis]

Working now. Thanks for all of incredible advice. Used a 2nd bottle to get the low-side pressure up to about 37psi and stopped there. Then checked the temp at the center vent later while being 72F outside, and it was blowing 39F! We'll see how it does this afternoon in the upper 80's. Hopefully I have COLD AC.

 

[El Hombre]

(quoted from post at 13:58:33 08/01/17) Working now. Thanks for all of incredible advice. Used a 2nd bottle to get the low-side pressure up to about 37psi and stopped there. Then checked the temp at the center vent later while being 72F outside, and it was blowing 39F! We'll see how it does this afternoon in the upper 80's. Hopefully I have COLD AC.

If it leaks out again, you can look for an oil stain on the visible parts like the hoses and condenser. Probably won't see any, so it's probably the O-rings are leaking at the connections.

Get a can of seal conditioner with R134a and inject that. The 15 year old system on the Buick was leaking, slowly. 2 years after the seal conditioner, still cold air.

DON'T get the sealer with some kind of goop that will actually plug a hole. You got a hole, fix the hole. But swelling and softening the O-rings to seal, that's a viable repair and won't foul the rest of the system.

 

[chadsd]

Rear ac lines are common to leak, corrosion where they go through the body. Look behind the pass rear tire for any signs of oil. Here in
south dakota our shop does several a year. If they use any salt in your area, my guess is they are corroded, and leaking.

 

[showcrop]

Wow! It looks like there are lottos different AC programs being taught.