DIY A/C Refrigerant Recharge

[ex_MGB]

For whatever reason, I've never delved into a/c refrigerant recharging. I just took my 10 year old BMW into the dealer to get the a/c looked at. Not a good feeling

The car had been sitting for 5 years so I guess the compressor seals were bad. Fortunately, at start-up it blew cold, but seemed to lose it after a few days.

Anyhow, the day after I dropped it off, I'm up at AutoZone to get a battery for my son's Nissan Frontier. I notice, of coiurse, the large display of R134 with gages. Some of the R134 cans even claimed to have a stop leak additive. I was regretting not taking a stab at this.

I'm a bit of a shade tree mechanic, maybe I need to expand my repertoire. Any thoughts or guides to doinf refrigerant charges oneself?

 

[Chris142]

Do not put the stop leak in your car! It might work for a few months or whatever but when it comes time to repair the system everything will need to be replaced as the stop leak plugs everything up.

To properly recharge a R134a system you must recover whats in the system, vacuum, add oil if necessary and charge using a scale. you cant really go with pressures with r134a.

 

[carlprop]

Chris142 gives good advice. Any A/C shop will not work on your car if they know stop leak was used. The gunk ruins their equipment. Don't use this stuff!

 

[The Critic]

http://theoildrop.server101.com/forums/s...ge=0#Post955396
http://theoildrop.server101.com/forums/s...ge=1#Post955909

Went out to dinner last night, A/C blew cool. Seemed a bit better than before.

 

[mechtech2]

Ford tests show that all AC systems lose refrigerant.
About 6-7 ounces per year.
It goes right through the hoses, and right out the line seals and compressor seal.
It would be a miracle if your car didn't need any refrigerant.
Over the counter fillers with a gauge are great. They are not for shop diagnosis, but for maintaining your system.

 

[Kestas]

If the system has no static pressure, you need to assume there is air in the system. Once the leak is repaired, this requires a complete vacuum and recharge. Air in the system will lead to problems.

If the system has some appreciable static pressure, but it doesn't blow as cold as it once did, you can go ahead and top it off with refrigerant.

When I charge a system, I turn the fan on high, in recirc mode, with the windows and doors open, and a thermometer in one of the vents. I charge a bit at a time until the vent temperatures don't drop any further. It helps to spray down the condenser with water during charging to keep the head pressures low.

Don't use anything with stop leak.

 

[ex_MGB]

Guys, thanks for the replies. really great to hear from people who have "been there, done that".

Dealer called, did just as was suggested. Evacuated the system and recharged (with a dye). Couldn't find a leak, so the damage wasn't too bad.

Kestas, I'm going to try what you say, my 10 year old Maxima could use a bit of an A/C boost.

MechTech2, thanks for the info that all systems lose some refrig over time.

Guess I'll be googling for a step by step recharge procedure.

 

[ex_MGB]

Critic, thanks for the links. Chris, good cautionary! Now I'm flummoxed!