Hi all- I could use a bit of confirmation here. I just D.I.Y. A/C overhaul after my car experienced the dreaded black death. A/C blows cold at 39 degrees coming from the vents at idle and under load on an 80 degree day with 35% humidity. The performance seems right and I am definitely not complaining because this was significantly better than when I had the car with an ailing A/C system. I could be over thinking it but can someone confirm if my low pressure readings aren't correct and won't cause any other system failures down the road:

Idle -25psi

Under load 1500-200 rpm: drops down to 10-15psi before compressor cycles off so pressure can climb back to 50psi before kicking back on

just to confirm, at no time did my vent temperatures ever climb above 45 degrees.

 

Low pressure cutoff appear to be working correctly. Your pressures and temperatures overall appear to be low, which to me is indicative of a vehicle interior that is already cold. I have drawn axes on the Honda A/C chart for this vehicle below. I would estimate that the condenser could be a replacement unit, or the cooling fan is moving more air over it. It is much lower than the chart would suggest, which is not a bad thing in reality. As long as the amount of charge was correctly dispensed, and the system was evacuated, I would say this is a normal system, that has an interior that has already been cooled, or the blower speed is not at the highest setting (recirculation mode could also be on).

 

thanks so much for your input! the condenser is certainly a newer unit as I replaced that once the compressor blew up. Also is there a rule of thumb as to whether an a/c compressor is cycling on/off to frequently? I have no baseline of what the typical length between it cycling on and off

 

The cycle time of the compressor is dependent on a lot of environmental factors. In colder temperatures, the compressor will cycle more frequently because less heat will be removed from the interior. This causes the low side pressure to drop too low, and cause the system to cycle. Likewise, in the heat of the summer, enough heat will be removed that the system may not cycle off for many minutes, as all the refrigerant will boil. This causes the low side pressure to be higher.

In short, with a defect-free system, the higher the ambient temperature, the longer the compressor cycle time. As the vehicle interior cools off the cycle time will decrease.