We need help trying to figure out an air conditioner problem. The compressor kicks on, but no cool air. About 60-70 pressure on the low side, 126 on the high side. We just bought this tractor with less than 800 hrs on it & the only thing we were told was that the ac had leaks. I am not the mechanic. I am asking for the mechanic. All this new fangled technology is not what he is use to, so trying to find him some help.
Massey Ferguson 5475 SA air conditioner not cooling
- Thread starter MyRivers
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Tx Jim
New Member
I think AC is low on coolant also referred to as freon. High side should be 225 psi on a 90+ degree day.
banjodunn
Veteran Member
G'day low side is too high as well as the high side low I would think the TX valve is stuck might be time for a full A/C service
Jon
Jon
Tx Jim
New Member
Why not buy a set of AC gauges and learn how to service your own AC system.?? It's not rocket scientist level work. I've been diagnosing/repairing my AC systems for years.
Assuming you have HFC-134 freon, ideally, you want your low side pressure to be about 30-40psig for nice cold temps across the evaporator core. Any lower, it may ice up or cut off the compressor via a low pressure switch. Much higher and the evaporator core is just not very cold (see here: Pressure - Temperature Chart for HFC-134a).
As in previous posts, your low side pressure is too high, and your high side pressure is unusually low. Like BanjoDunn says, this suggests that either the expansion valve (or orifice) has a problem with not restricting flow enough so that the pressure difference from high to low is sufficient. If the tractor has just an orifice, they seldom get BIGGER. Clogging (too small) is their usual failure mode. So the problem is very likely to be a malfunctioning thermal expansion valve. Assuming you DO have a TX valve and not an orifice, as a first step, check the sensing bulb and the tiny sensing bulb line coming from the TX to see if everything is securely fastened down and not kinked or broken.
- Jay
As in previous posts, your low side pressure is too high, and your high side pressure is unusually low. Like BanjoDunn says, this suggests that either the expansion valve (or orifice) has a problem with not restricting flow enough so that the pressure difference from high to low is sufficient. If the tractor has just an orifice, they seldom get BIGGER. Clogging (too small) is their usual failure mode. So the problem is very likely to be a malfunctioning thermal expansion valve. Assuming you DO have a TX valve and not an orifice, as a first step, check the sensing bulb and the tiny sensing bulb line coming from the TX to see if everything is securely fastened down and not kinked or broken.
- Jay
Thank you so much for the info. I am relaying everything to the mechanic who is actually doing the work. I believe he is going to replace the expansion valve, but I will update as soon as I know the outcome. All y'alls advice has been very helpful.