heat pump manufacturers

What make sense and what they do is two different things. Gauges cost money x the # of units they sell makes it a no-go. Everything they do, cheap overseas capacitors, microchannel coils and 1 pole contactors that should be 2 pole and no pressure switches that could save a compressor on refrigerant loss……they won't put gauges on. They have a planned life cycle.

Try these.

Less loss than a fly fart.

No, we can't have pressure switches because we now have to pay for refrigerant leak sensors for refrigerant that will not sustain a fire if you hold a torch on it and pay for ECM motors and other crap that costs a bunch to replace.

Next thing that will happen is homeowners' insurance rates will rise if you have R-32 or R454B due to flammability issues.

Insurance companies never loose

What will happen is they will be disconnected and bypassed. Just silly. They say the refrigerant will not sustain a fire even if a torch is put on it.

My ~2001 lennox has high and low pressure switches, they just screw on to extra access valves. It keeps it from melting down if one of the fan motors stops or it leaks. It doesn't really affect reliability. Other than cleaning, a capacitor, and a furnace blower motor it has needed no other work. I would like to figure out what to do about the plastic coated grill that the plastic is peeling off of.

And yet, the one I just fixed didn't melt down without any pressure switches.

The compressor's overload trips, and it takes longer and longer to reset every time it happens. Best guess on my dad's part was it was probably attempting to run without the condenser fan for a good 3 hours before he realized there was an issue.

Absolutely zero damage to the compressor, best I can tell.

I thought the pressure switches were an absolute must as well, until this happened. Now I'm kinda confused why they're needed? In fact, would a high side pressure switch actually make the compressor cycle more than it's own internal overload tripping (with a dead condenser fan)? On my unit I'm sure the circuit board would lock it out with an error, so that's good. But there's plenty of arguments against circuit boards in outdoor units as well and a plain contactor isn't going to lock anything out.

Obviously the low pressure switch serves a different purpose. I hear running with very high superheat is really hard on a compressor.

I feel it's best to ask the guys like @pecmsg and @EBEBRATT-Ed and @Harvey Ramer who work with this stuff all day every day what they've seen. We can guess all day long, but it's hard to beat real world experience.

The overload will shut the compressor down with inadequate condenser airflow but it will take longer than a pressure switch, the compressor will have to get hot in order for it to happen. The pressure rise will happen before the compressor starts getting excessively hot. Also the overload is usually internal so if it goes unnoticed for days or weeks it can burn out the contacts on the overload and the only way to fix that is to replace the compressor. It also may get hot enough to decompose a bit of the oil and/or refrigerant every time it trips.

My lennox has pressure switches and a time delay so it won't cut back in after the pressure switch cuts it out until the time delay elapses.

Every compressor has a safe playing field. Installing guardrails (pressure switches) is a good thing. They are relatively trouble free and frequently alert to an issue before equipment damage occurs. They also protect the consumer from knuckleheads who fix every problem with a Freon jug.

That being said; I have no problem installing a straight AC without pressure switches on a tight budget.

I think the most insane thing a lot of manufacturers are doing, is using R454B when R32 is a readily availible option. The insanity blows my mind actually. 454B is a blend with a substantial glide. R32 is a straight blend and more efficient.