Been a minute since I've posted here (I suppose that's a good thing, with zero issues right? lol)

My better half complained the AC in her 16 RDX takes forever to get cold, and then it's hit or miss if it even does get cold.

I thought maybe it was just low refrigerant. Added some and these were the pressures that we saw (attached photo)

I'm no tech, but I think the high side pressure is not correct for it being a 95 degree day outside. Adding refrigerant had no effect, maybe even a negative effect on interior temps.

My question is, what next?

Could it be a blend actuator issue? I know on the odysseys and other hondas this was a common issue.

Compressor? The AC used to work decent but it seems to be just getting weaker with time (which is why I thought it was a refrigerant issue).

Something else? Condenser issue? Whatever the part is that dries out the system? There's always water on the ground after driving so no clogged drain lines. No visible leaks with UV light either

Sorry for rambling. Any input or advice would be appreciated.

 

These pressures look very low, especially for a 95 degree day. How much refrigerant did you add?

 

We added less than 1lb, and the pressures didn't move too much. If the system has the appropriate amount of refrigerant, I was wondering maybe if the AC compressor itself is weak, even though it's still engaging.

 

If the system is charged correctly (which I doubt), I would start with the simple, change the expansion valve and charge the system correctly (create a vacuum for at least 30 minutes and charge it with 470 grams of freon).

 

This:


folks really need to understand that since AC is a closed system, if the refrigerant is low, it means that it leaked out somewhere.. so you really need to find the leak, then pull a vacuum and then re-charge with the proper amount of freon. the mass market of freon top-off options makes people think that there's an easy solution to solve but unfortunately not.

 

I'll look into the expansion valve, as well as following those instructions with the vacuum. Thanks

 

The system only holds 15.2-17 oz of r134a so I'm surprised you didn't see the pressures rise some towards the expected range when adding refrigerant, it's possible you were very, very low on refrigerant. The low side is way too low and so is the high side and this means a low refrigerant charge. Ideally, it's best to weight in the refrigerant to a empty and vacuum system but you might try adding a few more ounces to see if the pressure come up some and confirm the refrigerant charge is low. The main thing is you don't want to overcharge the system but based on these pressure readings you're not anywhere close to an overcharged system. I wouldn't condemn any of the parts in the AC system yet until the charge is correct. One tool that's really helpful when working on the AC system is an infrared thermometer, knowing the temperature of the high and low side lines in various key spots can tell you a lot about what's going on. The only other possible problem associated with these pressure readings might be a restriction somewhere else in the system but this is a much less likely cause and this is where the IR thermometer would be useful.

 

One thing I should have ask about is how the needles move when the compressor cycles on and off. Does the low side needle drop down quickly and by a significant amount when the compressor cycles on? In general do the needles jump quickly when the compressor cycles on or off? If there's a restriction in the system, either with the expansion valve or elsewhere in the system the needles will jump more when the compressor cycles, the gauge needles will more gradually in a normally operating system and within an expected pressure range.
One other thing you can do is look for any moisture or frosting anywhere on the lines and at the firewall where the expansion valve is, look primarily look at the high side line from the condenser through the filter/drier to the firewall. If there is any moisture or frosting that can be seen on the high side line that's is where the restriction is and if the expansion valve is stuck closed or there's some blockage in the valve you might see moisture or frosting at the firewall where the high and low side lines enter, the expansion valve is behind the firewall plate.