Ac wont take charge

[randylee14]

I have a 2009 New Holland TD5050 that the Ac wont take a charge. It had a leak which I fixed ( replace o ring on fitting) I put a -30psi vacuum on it for 45 min then let it set for 90 min it held so I tried to charge it . the compressor will only run for 1 sec then off for 3 with a can of Freon hooked up to it the low pressure is 55 psi when on and 40 psi when off the high is 60 psi and 45 psi, I have done this for 45 min no change , I then repeated this whole process with same results . I have been told it is low on Freon but it wont take any more less then 4 oz in system now. anyone know whats wrong?

 

[CalG]

I'm not familiar with your tractor A/C system, but it may be designed for a high side charge. If the pressure sensing switch only allows 1 second of compressor activation, It will be very difficult to do a low side charge. You may need to jumper the A/C clutch to keep the pump spinning.

It never hurts to add heat to the refrigerant while doing a low side charge. ;-)

 

[dadster4]

Warm the refrigerant can in hot water several times to increase it's internal pressure. Keep the can upside down when adding to system until compressor runs longer cycles- then keep upright to only add vapor after the compressor cycles become longer. Open the refrigerant can or gage set valve only when the compressor kicks in- then close when it 's off, the compressor will run a little longer after it gets enough refrigerant in the system. Keep the cooling fan on high and the cab door open. Charge the system in the heat of the day also.

 

[JRobyn]

High side pressures seem VERY low, even with the compressor only running intermittently. The compressor may be knackered. Do you know if your system uses an orifice or an expansion valve?

 

[TractorGuy]

My NH backhoe was taking forever to charge and I found the low side connection on the Harbor Freight gauges was the problem. I bought new port connectors and so far it has worked much better. It still has to have full can pressure to get the low side port connection to start allowing freon to pass through it. The design of the 134A connectors leaves something to be desired. ry opening the low side valve with a can connected and the port connector not on the tractor and see if you get a decent flow of gas out.

Your pressures are whacky but can't be trusted until you get it to take a charge. You could try pulling a vacuum on it and feed the freon in through the high side with the engine off. Let it settle a good while before stating it and make sure the high side valve is closed when you do. You should be able to get almost a full can in from full vacuum. I wouldn't do this normally as you stand a chance of damaging the reed vlaves in the compressor but I have done it on occasion. So far I haven't broken anything charging the first can this way.

Even when things are flowing correctly I always feed the freon as a gas and warm the can in hot water as I charge. The cold can will cool the water and you may have to refill with hot to swish the can around in. I use a 4 cup pyrex measuring bowl for this and just swish the can in circle in the water while I charge.