Ac work

[JOHNFAK]

Going to be vacuuming down my ac system soon ... And then recharge ... Any hints ?? Have the gear but not done before ,... ;)

[Wild and Free]

Knowing what type of gear / tools you have will help in giving advice. The technique is different with different types of ac tools and equipment.

[JOHNFAK]

Knowing what type of gear / tools you have will help in giving advice. The technique is different with different types of ac tools and equipment.

Just a vacuum pump with a 3 way manifold set ...... So attach ..... Vacuum down ... Hold vacuum ... And then attach/inject new refrigerant .... Basically ?

[Mopar1973Man]

Quick and dirty... http://mopar.mopar1973man.com/cummins/2ndgen24v/hvac/recharge/recharge.htm

[JOHNFAK]

Quick and dirty... http://mopar.mopar1973man.com/cummins/2ndgen24v/hvac/recharge/recharge.htm

Cool anything to be careful of ???

[Mopar1973Man]

Hmmm....

Make sure to vacuum down the system good. (Remove moisture)

Make sure to add oil if compressor is being replaced or any parts of the system being replaced. (Make up lost lube oil)

Don't add the freon as a liquid compressor can't pump liquid. (Can up side down)

Watch both lo and hi side pressures.

Don't over add freon because the pressure is low. (If you flood the evaporator then the freon can't evaporate and cause cooling)

Don't buy freon with oil charge (This will flood the system with too much oil and cause problems with cooling too!)

NO! -><- NO!

Use PAG oil charge

Then R134a Freon

[JOHNFAK]

Vacuumed down ... Saw a very small move in vacuum after 30 mins .. Like from 27 to 25 .... So I added 2 cans freon ... After turning on ignition compressor was stable ... And air temp was 49 in 77 day .... High pressure was 210 and low was 38 .... Was nervous to add 3rd can ... So stopped there ....

[Mopar1973Man]

About right... If your looking for the pressure tables they are located in the Dodge FSM...

[JOHNFAK]

Hey MIkeYeah but only 2x12 OZ cans ... and my stickers say its takes 2lbs. So I am only at around 1.5lbs ....... do you think I need to add the other 0.5 lbs ?? Was getig a bit worried on the pressure high/low based on your tables in that writeup you did

[Mopar1973Man]

That's the thing... The high/low pressures will change as weather changes. Like pressures will get lower as the weather get colder. Then the pressures will rise as the weather warms and the under hood temps rise it will push it higher... Tell you the truth... If you do a bit of reading there is a point where less is better. As long as the evaporator is not flood with liquid freon it will get colder. Basically the lower the low side pressure the colder the A/C will get. But the low pressure switch is the limiting factor. This keeps enough pressure in the system so the evaporator can't freeze. So it continually sweats instead. So if you got enough freon to keep the compressor running constant at say 1,500-2,000 RPM's then I wouldn't sweat it... Just chill out... (Yeah I was being punny)

[JOHNFAK]

So if you got enough freon to keep the compressor running constant at say 1,500-2,000 RPM's then I wouldn't sweat it... Just chill out... (Yeah I was being punny)

Hahaha - thx bud I am not convinced I don't still have a small leak .......... any tips of better ways to isolate the leak ....... I heard someone talk about specific tools like 'sniffers' or something ............. I am glad top be able to recycle my A/C for $30 tho ............ and get cold air So I appreciate that writeup you did as always

[Mopar1973Man]

Just get a can of UV dye and use a black light over the piping... If you don.t find any UV dye in the engine bay then its in the HVAC unit under the dash that simple... This when I pulled the pipe apart and there was still a puff of freon left...

[JOHNFAK]

Yeah I added PAG Oil and UV dye prior to AC freon.Not used the black light yet ................... seems to come out well on yours in that PIC ...... I remember lookign at it during the daytime at AC place that tried to fix it before - and was hard to see the UV light.Might get one and try and night - probably easier to spot the colors.Any old black light ?

[Mopar1973Man]

Any old black light works... But I'll tell you a secret... Once the dye is expose to the atomphere in about 6-12 hours the dye fades away so if you going to hunt A/C leak go out and take a drive with the A/C on and come back and check this will circulate the dye around so if the leak is on the high side it will bled for you and be visable for a short period.

[LiveOak]

Cool anything to be careful of ???

Be very careful not to add too much oil like I did. I used one of the freon refills like Mike shows in his pics above. It turns out that I just needed some freon and had enough oil. I ended up having to let some oil out of the high side schrader valve to stop the ugly noise my compressor was making. Been running good since.

[jlwelding]

I had to pull my evap. out to get motor out, there was no way to work around it, I know some have done it but. Anyway, I am trying to get my A/C back to 29 degree . What we did is record the temp 65 the humidity 72 and the pressure on the line (not running) was at 30. If I get luck and the temp's are the same I am going to shoot for it. But of course we will go by the sticker first then see what we can do.My a/c used to freeze you out at 29 degree in 100 degree weather and humidity. My question is what do you do about the liquid from the feon that's traped in the lines? Like what was mentioned, the liquid messes with the pressure in the system. It almost seem like the thing to do would be to empty the system and start over.

[Mopar1973Man]

That's why you draw a vacuum on the system to remove any freon residue and moisture. That why the measured amount of freon its to keep a person from over loading the system...

[jlwelding]

Ok I get it the feon gases are removed also with the moisture.

[JOHNFAK]

ok.Still have cold air and the compressor is not cycling too often. Haven't checked for leaks yet ...... might try this weekend.But my ambients are around 85 degrees ..... and my ac runs around 48-52. Someone told me as long as its 20 degrees under ambient ...... but ??? What controls how cold the air actually gets ?? The amount of freon ? The compressor ?? Should I be able to hit 30's with 85 ambients ? cheers

[Wild and Free]

ok.

Still have cold air and the compressor is not cycling too often. Haven't checked for leaks yet ...... might try this weekend.

But my ambients are around 85 degrees ..... and my ac runs around 48-52. Someone told me as long as its 20 degrees under ambient ...... but ???

Thats just a general rule of thumb which I use as a minimum depending on the piece of equipment and what type of system it has usually they will cool well below that point.

What controls how cold the air actually gets ?? The amount of freon ? The compressor ?? Should I be able to hit 30's with 85 ambients ?

The days of thermostatic switches went away long ago now the blend door is what controls inside temps. and as far as cooling the pressure switches control that now and the amount of freon is critical. The compressor cycles whenever the pressure switches kick it in and out which will vary depending on ambient temps and how much cab fan speed you have pulling the cold out of the evaporator and how much and what temp the air is flowing through the condensor.

cheers

Replys in red.