Driver's AC separate from OTR A/C ? OTR compressor power requirement ?

[someguy]

Is the driver's A/C completely separate from the OTR A/C on an E/J4500 ?  Or does the driver's A/C use the OTR compressor ?  How does one restore the driver's A/C if one removed the OTR compressor ?

Silly question... how much power does it take to turn the OTR compressor ?

Edit: 12 to 14HP  https://www.carrier.com/marine-offshore/en/worldwide/products/compressors/05g/

14 HP = ~ 10 KW = 40A ish on a 240VAC circuit.  Probably much more to start it, depending on the motor starter.

But really up to 27.5 HP, see page 11. https://www.shareddocs.com/hvac/docs/1001/Public/0D/62-10430.pdf

[richard5933]

If you are just going to run the a/c for the driver and not for the entire bus, then I'm sure you can find a different compressor that will do the job and consume less power. The GM A-6 rotary compressor comes to mind. One of those cools my entire bus - surely it would power the forward unit on a bus.

[fortyniner]

Direct operation of the compressor off the engine is more efficient than converting to electric and running electric compressor. For OTR that's a great way to go since the engine is obviously already running. Also,  the compressor may cycle which reduces power consumption. 
.
My old 4905 had dual A-6 for the entire bus full of people plus the driver had their own evaporator unit.
A single A-6 should easily handle the forward section of most buses.
.

[richard5933]

...Also,  the compressor may cycle which reduces power consumption...

Interesting to note that in the GM setup, the A-6 compressor operated all the time the a/c was engaged. To moderate temperature inside the cabin there is a valve to open coolant flow to the heater core, adding warmed air back into the mix. This was done to keep humidity levels down. I also suspect that a reason this is done is to avoid damage to the compressor from engaging it at highway speeds. My bus will not permit the a/c compressor to engage if the oil pressure is up at all - it has to be at the point it would be idling with a warmed engine.

[someguy]

In the E/J4500s is the driver A/C powered by the Carrier OTR compressor ?  Or is there a separate compressor for the driver ? 

Does the driver have A/C on buses without OTR A/C?

[luvrbus]

It is a all one system controlled by electronics the driver can have AC when the passengers want heat a very high tech system with self diagnostic holds 23 lbs of R134   

[richard5933]

Did you remove the entire a/c system or just the compressor?

[usbusin]

Did you remove the entire a/c system or just the compressor?

The question is directed to whom?  I believe the OP doesn't have a bus.

[muldoonman]

Would one look like this? Carrier O5G 41CFM

[richard5933]

Did you remove the entire a/c system or just the compressor?

The question is directed to whom?  I believe the OP doesn't have a bus.

I didn't realize that this was theoretical and assumed the OP was asking about a bus he was working on.

[someguy]

I'm trying to figure out how these things work prior to buying one.

23 pound of freon !

[Jim Blackwood]

Yeah, you can buy r134 in the 30lb bottles. Not too bad that way.

Jim

[ktmossman]

Yes, the Driver's A/C uses the same compressor as the rest of the bus.

FWIW, my plan is to re-use the mechanicals of the Driver A/C (everything in the front of the bus), but connect it to a stand-alone 12K mini-split.  That way I can use it OTR, but it could also function as a backup A/C unit as well.  My A/C expert friend has already verified it will work mechanically.  The only thing we have to sort out is the controls.  I will probably end up with a mini-split control pod on the dash somewhere.

[someguy]

Yes, the Driver's A/C uses the same compressor as the rest of the bus.

I have since found out that it is on MCIs.  Some Prevosts have a separate compressor for the driver's A/C.

FWIW, my plan is to re-use the mechanicals of the Driver A/C (everything in the front of the bus), but connect it to a stand-alone 12K mini-split.

I was wondering if that would be a viable way of doing it.  I'd like to do something similar.  Please keep me informed of your progress.

How are you going to power your minisplits while driving down the road ?  Alternator -> inverter ?   Generator ?

That way I can use it OTR, but it could also function as a backup A/C unit as well.

You mean you'd have an extra evaporator in the system ?   

My A/C expert friend has already verified it will work mechanically.  The only thing we have to sort out is the controls.  I will probably end up with a mini-split control pod on the dash somewhere.

Depending on the year of coach, the A/C control logic is implemented in the multiplex system.   And I'm guessing that the compressor module on a mini split just watches the freon pressure.  When it falls and hits a certain setpoint the compressor trips on a charges things up.  It might be very easy to implement a driver's A/C system using a mini split.

[ktmossman]

The power system is still a working plan (hell, it's all still a working plan).  I am going to be doing some experimentation with solar and large lithium battery banks.  The goal is to be able to run the house systems (including the two primary A/Cs) from solar/batteries.  But I will have a gen backup as well.  My thoughts on the extra driver A/C is that it would only run off of the alternator or generator.  Thus, it would only be used OTR or in extreme heat scenarios, when I will need the generator anyway.  When supplementing the house A/C, we would just use a portable fan to circulate it from the dash area into the rest of the coach.

On the re-using the OTR dash system, the original ducting, "cassette,' and fans are still there, plumbed into the vents. It is all a Carrier brand system.  I can use a mini-split and plumb it to the Carrier "cassette."  It is probably still theoretically possible to wire into the dash controls, but not sure it's worth the trouble.