How to recharge A/C when compressor not running?

[callbay]

My son's 08 Dodge 5500 pickup overheated due to the fan clutch not working. The A/C over pressured and puked out freon.

Fan is fixed but now the compressor not running. Can I charge the freon slowly until compressor will start? We checked fuses and all are fine.

Thanks a ton!

 

[440Magnum]

I'm assuming you know how to charge an AC system, have the necessary guages, etc.

The answer is yes, turn on the AC, apply charge pressure to the low side port, and when the pressure comes up enough the compressor will kick on and you can charge normally. There's a low-side minimum pressure switch there to prevent the compressor from pulling a vacuum on the low side and sucking in air.

 

[zanzabar]

You may need to jump the compressor to get it running in order to properly cycle the contents of the system. This is a blunt fix and you would be much better off getting it to a proper shop that has the right tools to read pressures, and ideally evacuate the system so that no water or other contaminants are present (which they most likely are).

Conclusion, get it to a proper AC shop!

 

[oldhp]

You would be far better vacuuming the system down to nothing and checking for leaks first. Then you can add the proper amount of refrigerant. These new systems are pretty exact on how much they take for the correct charge. They are not like the old R12 systems.

 

[Fleetmon]

the best way, as indicated, is to pull the proper vacuum, put at least half in (engine off) via liquid (which should allow the compressor to come in when the engine is started0 and then fill the remainder of the required amount via vapor.

 

[TFB1]

If there is still pressure in the system it DOES NOT need evacuated...

Proceed as 440magnum stated...

 

[Fleetmon]

yeah, my bad....I didn't read the thread thoroughly.....there will be refrigerant left in the system so add enough vapor until the compressor starts.....shouldn't take much.

 

[callbay]

There was still some pressure in the system. Tried to get the first can of freon in but it was like it hit a wall and could not get all the can in.

The compressor did not start and the pressure read very high, in the red zone. It started way down in the very low part of the green zone before I added freon.

 

[Chris142]

Whats the high side pressure? Those stupid low side guages on the can don't mean a thing! If you give me a high side reading and curant temp I can tell you if your low or overcharged

 

[default]

Pressure from the can kicks the switch on. Depending on the design, you might need to replace the blow off valve and vacuum down first.

 

[oldhp]

The only correct way is to vacuum down and add correct amount. Otherwise its just a guess.

 

[Donald]

You need a normal A/C gauge set to work on a vehicle's A/C. Once you have that you can tell where you stand. I would not mess with it using just a cheap low pressure gauge.

 

[demarpaint]

Originally Posted By: oldhp
The only correct way is to vacuum down and add correct amount. Otherwise its just a guess.


+1 it could also end up being a dangerous guess too.

 

[dishdude]

Put the can of refrigerant in a small bucket of warm water to keep it from freezing up.

 

[TFB1]

Originally Posted By: demarpaint
Originally Posted By: oldhp
The only correct way is to vacuum down and add correct amount. Otherwise its just a guess.


+1 it could also end up being a dangerous guess too.


Bah unless you can't read a gauge there is absolutely ZERO wrong with adding refrigerant to a system that's a little low...

If we were talking a sealed system like in a window A/C, refrigerator, freezer, etc I'd agree with you... No that statement doesn't include a home system, I'm yet to see a tech that didn't connect their gauges and add what was necessary to bring pressures back to the proper point... With varying installations of the outside unit(Compressor & condenser) and the evaporator, the same components can require different amount of refrigerant to operate in the proper pressure range...

 

[jrustles]

Make sure the can is inverted, so that the the liquid is forced into the system. If you pressurize it with gas, you'll have a heck of a time trying to get liquid in there without purging or jumping the compressor.

Originally Posted By: dishdude
Put the can of refrigerant in a small bucket of warm water to keep it from freezing up.


Yes, warming the can will help to motivate the liquid refrigerant out of the can if it stalls (compressor off method). Again, always charge with the can's bottom-end up.

Also, double check your static pressure (against an R134 static pressure/temp chart), to see if you have any liquid in the system right now. If your STATIC pressures are inadequate, it will indicate that there is no liquid present in the system and you will without a doubt need nearly a full recharge. If there is liquid refrigerant present, you'll need a top off only.

If you do it yourself, just be careful. No one will die, no one will be injured (IMO one would really have to try to be injured) you just need to read up a bit, understand what you read and take care in doing it.

best of luck

 

[440Magnum]

If the compressor didn't kick on, then its possible that the over-pressure "eVENT" (pun intended) did more than just pop the relief valve. :-/