Hey guys. Last summer my A/C was great....pretty cold.

I did my motor in my car, got it charged, and the A/C was warm. I had the entire A/C system apart when I had the motor out condensor/compressor/dryer so I figure the O-Rings got ripped apart maybe.... so after the first charge I figured it was the O-Rings. I had all the O-Rings replaced....Charged up again and now the A/C just really isnt like a SHOT of cold like it used to be....Its cool just not really cold as last summer.

Now as for the Freon. Ive been buying the canisters from Wal-Mart and my macanics been using them to charge the system. TWO at a time. Do you think that may be the problem why its really not that cold ??

Are there different grades of Freon that would really make a difference ??


-matt

 

You need to check the low side and high side PSI value. The long A/C thread has a lot of info in it.

 

Im taking a ride down there tomorrow...He should know what the values should be at...but do you you know them off hand maybe ??

-matt

 

At 75deg F ambient, low side should be 25PSI, high side 150PSI.
At 100 deg F ambient, low side should be 30PSI, high side 200PSI.

 

another thing the drier takes moisture out of the system, they can only stay open for a couple hours before they pull too much moisture out of the air and become trash. i'm not sure how much of an effect this would have though.

 

That is true. Florida is probably worse than California. Even when system is empty, keep the system close is a good idea. The new Nissan dryer I bought only came sealed in a plastic bag.

 

I replaced the dryer on mine with one I got at Advance Auto and it looked identical to OEM. It was about $26. The one at Auto Zone was $63. The system works much better now.

 

Alright guys. Alittle a/c problem update. I went down to the shop that charged the system and we added another can. Got the air temp to 55...not too good either way. It stayed cold for the day but is back to NOT being that cold. Its cold but not super cold.

Could the compressor be shot or could it just need a good leakdown with vaccum and a good re-charge ??
All of the front O-Rings have been replaced.

-matt

 

What are the high and low side pressure now?

 

When I put in that second can, it was right around 32ish. I would think its at about 25 right now because its acting just like it did before I added that extra can.

-matt

 

If your mechanic put your system in a vacuum, then he should have let it sit for atleast 15 min to see if there was a change in vacuum this would tell him there was a leak in one of you rings before going ahead and charging the system, also check the low side hose, where the rubber meets the alum for leaks (from vibrations, heat, etc) with a leak detector- if u don't have a leak detector, make a mix of Dial soap and water and spray it on the connections and rubber hose if you see any bubbles-> you have a leak were the bubbles are coming from. BTW fsm calls for 1.43 lbs of refrigerant, just shy of two 12 oz cans, add to much and ur operating temps will be off, possibly shut comp- good luck matty.

 

Getting the right amount of freon in the system is tricky. The shop did replace the expansion valve to get my job to work.

Is the valve or the evaporator frosted over?

 

My symptom: low side getting up to 55psi and cool (70deg). It's supposed to be 25-30, so I have my mechanic drop it down, and it's warm. Maybe Matty and I have the same problem, w/the system being colder when overcharged.
Jae

 

Speaking of Freon grades, where to get PAG oil? And how much, and how to measure?
Jae

 

R134a is all you need, the system was designed with this refrigerants properties in mind. You can get PAG at any parts store or walmart, IMO charging by weight is best because the factory charges this way, both oil and refrigerant. FSM has all specs, you'll need a pocket scale (specialty tool) to see how much is leaving the cans. Take it to a shop that dials in the charge with a scale (hard to find though), most charge by pressure and as SVI30 said this is tricky because ambient temp and operating temps are constanly changing.Plus because the charge is never exact when charging by pres, this is why it's never as cold as factory. In residential/commercial a/c we use a superheat method for charging, however most techs still charge by pressure<-is this correct? Not neccesarily, but it's approximate (isn't working at optimum). Automotive application is more sensitive because of the sun, speed/rpm's, and almost no insulation to keep the cab cool for long periods, basically there's alot of cooling loss in automotive because of varying factors.

 

Our Calsonic CWV618 use PAG46 oil and it was Castrol brand from Pepboys. The bottle is 8oz and I used nearly the entire bottle on a new compressor which was shipped dry.

 

I had the same symptoms and changing the expansion valve fixed it. This is not an expensive item to replace. To open the evaporator box, you have to remove the glove box, remove the bottom metal bracket. Cut the plastic piece below the glove box between the two screws on each side. Then remove the front screws and clip on the evaporator box and force it partly open.

 

In case any one needs a scale harborfreight.com has one on sale for $16> item# 95363-1vga

 

Well I got the system totally evacuated the other day, and charged with the correct amount of R134a and its cold as ice. Thanks guys

-matt

 

its all about temps and pressure