Dash AC Question

[bluwtr49]

Quick question regarding dash AC.

My system high side pressure is ruining a bit hit...(slowly rising to ~350 psig at 90F) so I'm thinking I will evacuate the system and pull a good vacuum for a couple of hours than refill. I'm doing this in the hope that I might have some moisture in the system causing ice crystals in the TX valve.

My question is: will I need to add/replace compressor oil when I refill with refrigerant? And, if so, roughly how much?

Any other thoughts about what to look for?

[bluwtr49]

I popped out to the coach and took readings again. High side went to 315 psig at 77F, low side 22 to 30 psig. It took about 25 minutes for it to stabilize and I could see the pressure change as as the TX valve would operate. I would say the operating range was 280 to 320. Generally if the high side drops the low side went up slightly and vice versa.

[RLS7201]

A restricted TX valve will actually cause both high side and low side pressures to drop. With restricted TX valve, the compressor has less refrigerant to pump and the pressures will drop.

Richard

[MountainAir05]

What was the low pressure reading? There related.

[bluwtr49]

Thanks for all the replies.

I suspect the problem may be elsewhere but, on the other hand, it's pretty cheap and easy to replace the refrigerant so I'll see what happens.

The condenser fan is working properly, the clutch seems fine and I can see the pressure change as the TX valve does it's thing. Pressure is highest when the system has both AC fans running on high speed and drops to ~320 psig when the fans are switched to low speed. It cools very well with the outlet ducts showing ~48F at 90 F ambient

This all suggests I have a slight restriction someplace and I'm just hoping it isn't an issue with the hose deteriorating.

[allbrandauto]

oil in system is circulated by refridgerant so yes when we use are recyle machine in the shop you loose about half a oz. but you will find your problem in the cooling fan or fan clutch

[fishingbob61]

Just a thought, is the cooling fan working on the condenser?? If not that could cause high pressure.

[dougrainer]

1. Doing what you are doing will not fix the hi pressure problem. But, there is nothing to lose by trying other than the cost of refrigerant.
2. NEVER add oil to a system. There is a specific amount of oil in the compressor oil reservoir. adding oil can over saturate the system and cause low cooling and gum up components. To add oil you remove the compressor and drain the oil and flush out the system then put the specified amount of oil in the compressor for that particular compressor. Some new compressors have NO oil and have a chart for the required amount. Doug