[HO455]

I have discovered that the rear defroster moves so much air that when it meets the heat from the front defroster next to my shoulder it fogs the driver's side wndow. I guess 2 fans would have probably been enough to do the job.

At some point before 12/5/18 and after 8/29/17 I replaced the pressure switch for the compressor. If I still had a memory would know when. Thank goodness I have this thread to help me if only I could remember to post everything.
Anyway at some point the pressure switch that was installed when I bought the WMB failed and I replaced it with a new one from Viair. I chose the Viair switch due to the nice rubber protective coating on it and I felt it was a better brand. However it has failed in the on position. Thankfully I decided to install the pressure relief valve in the system otherwise who knows what else would have broken.
After replacing the switch and inspecting it was noticed the deterioration of the outer coating around the wires (photos 1&2) so I cut the rubber coating off thinking there might be water underneath that was shorting the wires and keeping the compressor running.
I didn't find any sign of water or shorts so even though the coating wasn't looking good on the outside it was still keeping moisture out. When I looked into the air inlet port on the bottom it was obvious the problem is corrosion inside of the switch.
I find this unacceptable! This is a pressure switch sold for use in a small tank automobile system where there is going to be moisture/water in the tank. It should not be so susceptible to water damage.
For a replacement I used a Air Lift Pressure Switch # 24544. At least the body is brass and should be less likely to corrode.(The brass you see in the first 2 photos is a 1/4 NPT to 3/8 NPT adapter bushing.) Time will tell though. I also went to a lower PSI range since I no longer have front air bags. That should reduce wear on the compressor.