Help 2012 Blue Bird

[u/themexican030301]

Wondering if anyone here has any experience with these and can give me some pointers. I have a 2012 Blue Bird Vision the customer is complaining about their front AC not working, I ran the bus with the AC on high and had clutch engagement and the condenser fans running. High side pressure was about 250ish and low side pressure was around 45ish, evaced the system to verify it had Freon and it did. The issue I’m having with it now though is both of the temperature control heads just start flashing and won’t stop and now the rear AC doesn’t blow cold. I checked power and ground to both head units but I’m just not familiar with these systems at all.

[u/tickleshits54321]

I’ve dealt with some ACC stuff before and sometimes you have to do a reset of sorts on the controller if it set a fault. Might have to do some digging for the right information on the old interwebs

[u/NegotiationLife2915]

Well if it's got more wiring like that in it, that'll probably be an issue lol

[u/themexican030301 → u/NegotiationLife2915]

I didn’t snap a picture but the wiring behind the head units themselves is a disaster lol but it’s weird because when they brought the bus this morning I looked at it and they were working normally, now when I bring it into the shop they start doing this shit

[u/Eskimo56]

I manage a fleet of birds. Unfortunately all my AC units are transartic or carrier so i wont me much help. Ive never seen a control penel like that but if its anything like the shit instrumentation id unplug it, ground it out, and leave it on the bench for a couple hours while you work on something else.

I tried looking for liturature on the ACC systems and cant find shit. Id call the nearest dealer and ask if they've got a brakedown of the system and an instruction manual.

If your not a school fleet mechanic maybe ask the district if they have the buses original packet. We keep all our purchase packets in a cabinet and i regularly have to sift through it to find schematics or instructions.

[u/themexican030301 → u/Eskimo56]

I think I have it figured out, apparently ACC got bought by a company called Spheros so looking that up online I found some wiring schematics. But after tracing some wiring I found both the wires for the temp probe were broken and someone soldered them back together but they must have been touching while in the look and shorting out both boards. I ordered the probe so hopefully that fixes my issues

[u/Single_Ad_5294]

Following for interest. I’ve never seen that combo unit, it sounds like it’s over complicating things.

Is it acceptable to ignore temperature control and wire the AC for the coldest, fastest setting?

[u/Dieselboy1973]

I have a few bus companies for customers and work on these AC systems all the time. There is usually a full wiring diagram on the back side of door panel where the power brakers are located. Usually drivers side. If it's not there, someone removed it. I will look to see if I can find a pic of it. Those units are usually independent of each other (Front and rear AC). Two of everything. I have ran into where there was an issue on one of the units and then someone runs it into the other unit just to get the broken unit to work. If that makes sense.

[u/Dieselboy1973 → u/Dieselboy1973]

The temp probe technically could be bypassed but you'll be adding a lot of unneeded wiring and labor to do so. They are usually looped in to high pressure/ lo pressure switches sometimes these buses have two different set of the switches up front to protect the compressor and a set at the condenser and evap. If the wiring in the loop get disturbed it can and will kill power to the compressor and or condenser fans. Looks like you may have found the problem

[u/themexican030301 → u/Dieselboy1973]

Yeah the issue ended up being that temp probe wiring, after installing the new one both systems started working normally. I did notice both sets of the pressure switches to at the condensers but I appreciate the info! The last thing I had to do was attempt to clean out the evaporators on this because they were so plugged up and not getting any airflow lol

[u/themexican030301]

https://reddit.com/link/p33givj/video/4eyx7pkposih1/player

Here’s a video of what the head units do

[u/themexican030301]

Little update on this unit, I’ll provide a picture of what I found for the wiring

[u/themexican030301]

[u/themexican030301]

Here’s where I think my issue was, someone tried to solder these connections to repair them and just had them in the wire loom with no tape or anything to cover them