OTR Bus Air

[phorner]

After spending a week in Charleston, SC and headed south toward the Mobile Oyster Fest, we're cruising nicely along I-95 when I decide to switch on the bus air.

Everything appeared to be fine, cold air, etc. when the "AC HI Pressure" warning light came on. This happened 5 to 10 minutes after turning it on.

We've been using the bus air without a problem all along the last 6,000 miles or so, and as recently as a week ago.

Shut off the AC for the remainder of the day until we got to our next stop where I turned it back on to see if the problem would duplicate itself. Ran the bus AC for about 10 minutes while we were waiting and the warning didn't re-appear. May not have been running long enough to duplicate conditions?

Anyway, is there something that I should be checking to determine if there is, in fact a problem? Assuming there is, is this a major project to get into?

I have zero experience with this....

[Jon Wehrenberg]

If I were to guess Paul I would say the first place to look for a problem is to see if the condenser fan is working.

Run the bus on fast idle, set the switch to AC and go out to see if the blower in the condenser bay is functioning.

If it is not locate the circuit breaker for the condenser fan and see if it has tripped. Reset it if it has. I verify the CB has tripped with a multi-meter because visually you cannot tell if the breaker has tripped, and there are at least two.

I have seen the circuit breakers for the big OTR fans in the following places so I won't presume to guess where yours is located:

87 Liberty.........top of first bay, driver's side.
92 Angola.........top of third bay, driver's side
97 Liberty.........rear wall, passenger side, condenser bay

That is a common problem and if it persists the CB may have just gotten lazy and needs to be replaced.

[Jon Wehrenberg]

Forgot to mention, running it 10 minutes the internal pressures may not have yet built up. If in fact you can run it longer without problem it is not the CB. It may be blockage of the condenser coil. Other than that I can't help.

[phorner]

Thanks, Jon.

I'll give it a shot....

[Jon Wehrenberg]

Paul,

I forgot to mention the blower motor might not run because the brushes are worn. According to the prevost spec they should be replaced at 3/4" of length. If the CB has not tripped, but the blower motor isn't running, check the brushes. They are easily removed, although access to the ones in the rear are a little tricky.

I wrote an article once that may be listed under information sharing about the brushes.

I also check all the relays for open circuits.

Jon

[MangoMike]

Paul,

In the bay with the condensor fan is a grey box with a couple of solenoids. The old car starter type.

Picture 7.jpg

I've had two of these fail on the Liberty. So it's worth a check.

Mike

[Denny]

Mike,
Thanks for the revelation that something failed on a Liberty! I thought Libertys were direct descendants of Adam and nothing ever went wrong with them or if there was a failure, the Liberty gods performed a miracle and you never knew about it.

[Jon Wehrenberg]

Denny,

Forget what Mike says. He has bailed on us Liberty folks and is now a left coaster with his Brand M.

The critical part is to read Paul's post again. He said it quit working, so he left it alone until the next day and it started working again.

I'm not supposed to tell people this secret about Liberty coaches, but since Paul let the cat out of the bag I guess I can. Liberty support is so great, if they even hear about an owner with a problem they send a team of experts out at night to track down the coach and repair it.

Of course you guys that drive the CCs won't believe that because your guys don't even answer the phone. In fact, I think their phone has been disconnected.

[dale farley]

Denny,

CC called me a month after I ordered an $89 part to make sure I got it and finished the repair. When has Liberty done this for anyone?

[phorner]

You're right, Jon.

Once Team Liberty got a whiff that one of their devoted might even THINK that there could be an issue directly related to the comfort and convenience of a LIBERTY COACH, they were on it....

Anyway, in about 10 seconds they explained that, on the rare occasion that the blower won't run, the usual suspect is either a dirty condenser coil (extremely unlikely as Liberty owners are well known to take extraordinary care of their beloved busses) or a failed relay.

Also, it should be noted that both the condenser and evaporator relays and breakers are conveniently well marked and located in a sealed box in the evaporator bay.

I ran the bus at high idle, turned on the bus AC and the blower runs just fine. So far, I've been unable to duplicate the warning light indication.

Liberty Coach details this phenomenon as typical "Owner Angst". Most Liberty owners simply feel left out of the crowd when the owners of other converted busses start detailing their tales of trials and tribulations, and so the occasional mishap, either real or imagined, is presented so as to afford the Liberty Owner an opportunity to join the conversation

Joe C..... you are hereby sworn to secrecy regarding any work, er.. "adjustments" that you may or may not be performing in January which I will neither confirm nor deny to the general POG public....

Mike, thanks for the relay info. Might be worth my while to carry a spare. Are they available any where in particular?