Replacing Batteries/ Over the Road A/C

[MyPrevost]

I spent the day removing my old chassis batteries, cleaning, scraping, painting, and installing new ones. The coach originally had Volvo 950 CCA commercial heavy-duty batteries, which I replaced with matching Exide batteries (920 CCA). After charging the coach for about an hour with my built-in 24-volt, 35-amp charger, it started right up.

While the engine was running, I turned on the A/C to cool down the bus, but it only ran for about five seconds before shutting off. Now it won’t turn back on. I’ve checked all the circuit breakers and fuses related to the A/C system, but none are tripped or blown. Is there anything else I should test or check before reaching out to Prevost or Liberty?

It feels like every time I fix one thing, something else breaks!

[MyPrevost]

What exactly isn’t running? Is the evaporator blower operating and air is coming out, but it’s not cold? Or is the issue that the compressor won’t engage?

[MyPrevost]

Gary,

I once had a similar issue with a weak circuit breaker in a previous coach. The big red circuit breaker didn’t look tripped at first glance, but when I used a multimeter, I found it had actually failed. It took a special tool to reset it, as my thumb just couldn’t apply enough pressure.

I recommend checking for continuity in your circuit breakers. You can find the electrical diagrams on the Prevost site, which should help you locate the AC controls. In my experience, they were positioned at the top of the first bay on the driver’s side, but your setup might differ.

[MyPrevost]

Both the fans and condenser aren’t functioning, so I suspect it might be a main breaker issue or a problem with the control circuit. The dash air fan operates, but there’s no cooling. I’ll do some further investigation today. I’m curious—if my batteries aren’t fully charged, could that potentially trip a breaker or cause the system to shut down? That seems possible.

• This reply was modified 2 months, 1 week ago by MyPrevost.

[MyPrevost]

I went back to the Prevost Operating Manual and found that the OTR system won’t function properly if the batteries aren’t fully charged. Even with the engine running and charging the batteries at over 15 volts, the system shut down. I plan to charge and equalize my batteries over the next few days.

[MyPrevost]

Gary,

I was going to suggest that, as the condenser and evaporator motors draw a significant amount of power. It would be wise to locate the breakers to check if any have tripped, especially if the AC doesn’t turn on after charging the batteries.

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