Getting a car that's been sitting 6 years back on the road. A/C compressor kicks on but pressure on the gauges are low. It's in the low 40's today. Any problem doing an evac and recharge? I was surprised it even worked. Don't they have a sensor to prevent operation below 50° or 55°?
Lowest temp you can charge A/C?
- Thread starter atikovi
- Start date
Someone asked if they could recharge in cold weather and someone else answered yes, but that doesn't say if they mean 50° or 5° is considered cold. I'll assume if the compressor came on, it's not too cold.
Yes the compressor cycles in relation to the suction pressure. So if it’s running then it’s running, I’ve charged many systems when it is cold. You may have to heat the refrigerant container and it may take a while to get the entire weight into the system but if it’s running it will work eventually.
Charged up find with heated tank half full. Glad I don't need a new tank anytime soon. Prices are more than triple what I paid less than 2 years ago.
Hmmm, my system has a pressure switch that only allows the compressor to engage when the pressure is higher than x value.. Anyone else have this feature?
Around 30 psi or so. System gets to that after a few ounces flow in.
Yes they all do. For one thing it helps to keep liquid out of the compressor.
Forgive my ignorance, my understanding is that the oil lubricates the compressor? Am I wrong here?
Meaning that the pressure needs to be high enough to engage the compressor, thereby saving your compressor from running with out lubrication?
No the oil lubricates the compressor. I was talking about liqufied refrigerant.
I see that now. Thanks!
Try Sunday afternoon. It's supposed to be in the mid 50's then.
My 134a recovery machine decided to act-up today, Needed to finish up a engine swap.....
Using a 30 pounder roughly 80% full, Set on my Scale upside down (Liquid). I was able to get the entire 1.04 pounds in the system using a Mapp to heat the cylinder.....Without the engine/compressor running.
Then I manually rotated the compressor to clear the Liquid just to be on the safe side.
IF you know there is enough oil in the system, then any temp safe recharge is possible as long as you have access to the HP side via a port after you pulled a vacuum on the system AND you know the correct mass of refrigerant to insert .................. going in via the HP side (and NOT LP side), the liquid will flash and circulate automatically throughout the whole system with no danger of damaging the compressor.
If the system only needs "topping-up" then you need to know about AC theory and have access to the P/T tables for the specific refrigerant
If the system only needs "topping-up" then you need to know about AC theory and have access to the P/T tables for the specific refrigerant
Always evacuate, always charge, by weight, liquid refrigerant to the HIGH SIDE ONLY (to avoid damaging the compressor valves), finish with low side if necessary making sure to vaporize liquid (by only cracking open gauge low side a little, low gauge bouncing, or a kwik charge/vaporizer). Keeping tanks indoors helps to increase tank pressure, & charging inverted/liquid helps too. I don't top up outside in winter, too easy to overcharge! (Always nice to have a question in my specialty!)
When I use a machine, I always and exclusively use the HP port to charge. Unless the HP port is not there or can't be reached or something. Exactly for the reason you describe.
I did do some big systems where we didn't know the exact weight it took, then I do it with the system running after a low initial fill, and monitor the pressures and temperatures. But these tend to be big systems, taking over 50 pounds of refrigerant.
Every manual I have read says to charge through the low side. The compressor puts out much more pressure than the tank and you could explode it.
Similar threads
