[HO455]

I did some M&R yesterday. On cold mornings the air compressor had started cycling on and off as it approached the shutdown pressure. This was really messing with the alternator. The lights would go bright, dim, bright dim..... I pulled the compressor relay to make it stop and headed to work. That evening after work I could not get the problem to reoccur. So I crossed my fingers and hoped it was fixed. Since I am old and out of coupons I was sure wasn't the case so I put my test light in the truck. Of course several mornings later it happened again. I jumped out of the truck and did quick check of relay by touching it showed it was cycling with the compressor. So it was an electrical problem.
I put a test light to the coil power to relay and found the voltage was constant. That ruled out the pressure switch as a source of the problem. However when I checked the power to the relay from the battery it was cycling on and off. Definitely peculiar,so I pulled the relay and headed to work.
Today I began by following the circuit back to the battery. The next component was a circuit breaker. I had installed a 20 amp automatic reseting circuit breaker back when the WMB was in the body shop. Since I couldn't get the problem to reoccur I made the assumption the circuit breaker was at fault.
Now to confirm whether the circuit breaker was bad or the compressor was drawing more amperage than before thus causing the breaker to open, meant taking checking the amperage of the compressor.
To get a reasonably accurate amperage reading I put a jumper across the circuit breaker then toggled the power manually while watching my meter. This showed there was nothing amiss with the compressor. The amp draw at starting pressure was around 14 amps and at shut off was 18 amps. To me this meant the circuit breaker was tripping early. I have not confirmed it but, I am assuming the compressor draws a bit more amperage when it is cold. It has been in the mid 40's when I leave for work lately.
I bought a new 30 amp circuit breaker to replace the 20 amp one. (First photo) I would have preferred a 25 amp one but I couldn't locate that size. The original 20 amp one was actually correctly sized for the original compressor that came with the truck. When I replaced the compressor I saw that it would be drawing 18 to 20 amps which is pretty closed to the rating of the breaker. Last photo the green arrow indicates the new relay.
I guess my borrowed time had expired.