AZ vs ViAir vs HB pressure switch?

Automotive Onboard Air Systems
1

I’ve been using an AZ 110/150 on my ViAir 450c compressor for quite a few years without issue.

That is, until recently when I noticed the compressor was taking a little longer than usual to shut off during an ice cold rain storm (my tank and pressure switch is mounted to the chassis)

Drained the tank multiple times and it refilled to 150 as usual, but after hitting a few potholes, the switch would somehow make contact again and continue to run until I hit the main cutoff :o

Today was a dry day and I did multiple drain/refills without issue, but I figure I’d replace the switch anyways…

Looked up on AZ’s website and couldn’t find a 110/150 switch listed :confused:

Only found 140/175 and 160/200

Did a little more searching and found a ViAir 110/150 switch (dual prong) as well as the HB 110/150 (dual wire)

Now, back in the day, I used the old ViAir pressure switch relay and it was garbage.

It always cut out early and never gave me a full 150psi as it was rated for.

I’m hoping the stand alone switch works better, but how does it compare to the HB units?

2

My ViaAir 160/200 seems to cut out within ~2psi of 200 in cold (45F or colder) weather, but cuts out earlier (~6psi shy of 200) in warm weather. The warmer it is, the sooner it seems to cut out, as I’ve had it cut out ~8psi shy of 200 in our hottest (~100F) weather.

On the flip side, it seems to cut on when my readings from both a digital sending unit AND from a manual, glycerin-filled gauge are near ~184-188psi. This might bug some, but I prefer it since my system is free of leaks and because this oddity brings the compressor on sooner, which translates to a slower depletion or quicker refill when using tools or honking.

I’m fine with it, as-is, but this level of variance might be more than some care for. YMMV…