Air Conditioner Test

Old-Biscuit wrote:
Complete misunderstanding of what that 20* drop is in reference too.......

A properly functioning A/C unit should be able to reduce the RETURN air temp by 20* when compared to the DISCHARGE air temp.

Nothing to do with OUTSIDE air temps.

RV A/C Units 'recirculate' the inside air of rig. They only cool the air inside.
So measure the air temp just before the evap coil and then again on the outlet side of evap coil to get an idea of how the A/C Unit is functioning.

But CavemanCharlie was seeing a 37° drop across his unit a couple of minutes after starting it. If you could only get a 20° drop he would have been waiting a while to see the register temperature drop below 75°.

I suppose he could have been recirculating in the unit but I'd still expect it to take longer to cool down if 20° was really the limit.

The compressor is the heart of the unit. Its discharge pressure will be whatever is required for the condenser to condense refrigerant at the outside temperature. The suction pressure is determined by the compressor as well. The higher the discharge pressure (determined by outside temp) the higher the suction pressure.

The suction pressure in turn governs the evaporator temperature. The evap temp will be the boiling point of the refrigerant at the suction pressure. Lower suction pressure means lower evap temps. (This is why evaporators will freeze if the charge is too low)

To make that long story short, it's the outside temperature that governs how cold it can be inside your trailer, car, house or anything else since the compressor is the fixed part of the equation. As long as you have enough compressor and condenser you can be comfortable inside at just about any outside temperature.