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Prevost Dash Air/Heat
As I headed out from New Orleans (good times had by all during Mardi Gras) heading to FL, my Prevost dash air/heat cycled off every minute or so. I could turn it back on, but within a couple minutes or sooner, it turned back off. My Aux dash air stayed on.
After a rest stop and turning the bus off, the dash air stayed on the rest of the trip. It couldn’t be a blown fuse or circuit breaker, or I would have had to turn it back on manually.
After looking at some schematics, it looks like maybe the dash air and dash aux air may be on different electrical circuits. One on the 24v and the other on 12v. I still don’t know why this happened, but anyone else ever happ
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6 Replies
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Tim,
Read my post and repair of similar issue dated 1-15- 2016 in HVAC section.
AL
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Keep in mind boy’s, BA has OTR and Tim has Prevost dash air. So BA’s control has driver and coach air functions and Tim has dash air and aux functions.
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Thx Al … But no doubt Tom has a point that they wired your OTR differently since the load is much more. But hopefully your driver side, where my problem occurred, would be wired the same. Read your Thread and it may indeed be the dash air box. Prevost quoted me $800, but I’ll wait ti it fails since it’s working now. I’ve not had any issues with the speed of the fan, just it turning off on its own. I don’t think it would be the temperature sensor since that would not turn the entire unit off.
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Our fan speed came on after pressing the on button, with a 2-5 second pause first time. Speed remained constant only to go on and off. This happened at any fan set speed.
On our Canada trip I checked what I could without taking dash apart. At one point worked flawless for 3 days. 4th morning punched the on button and we’re back to the same problem.
It was a general opinion that the fan regulator was the problem ($180) and the cheapest part in the system, fairly easy to replace with minor dash and panel removal.
Then replaced fan blower, that is a whole separate issue as some jack ass really messed that up trying to re-mount blower. Finally the jack ass gave up letting it sit on top of heater core unbolted. Probably a bad armature in the blower motor. ($500)
That left the dash control at $800 smackers. If I had to make a WAG (wild a** guess) your description sounds pretty close to my on-off blower speed complaint.
Prevost has an retro fit dash unit which includes a much better sensor then original installed. I have replaced the dash box and installed the sensor upgrade, ran the system 3 times in the bus barn and taken a road trip turning the system on and off multiple times. It’s working as designed now.
Pressing the ON button now fan is on in nano second.
Use the PC private email so we can talk by phone if you have questions.
AL
New box –top photo with sensor included. The plug in wire harness adapts too existing 2 plugs. The sensor connector must be found on drivers side dash wiring. I found mine zip tied inside large loom on back side of radio.
new sensor re-mounted above drivers right leg, parts come in kit.
Blower motor inside air box, mounted on top of housing. Regulaor mounts back side of regulator plate
New control box (sku tag) showing installed below radio housing.
I screwed around for a couple of hours trying to get at the back side of dash box mount screws loose…. 2 on each side with a holding plate.
There is a trick to getting that dash box out and that my friend will cost you BBQ’ ribs or pizza when you come through KC.
And Truk…no telling
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Thanks Al,
So the new sensor upgrade is something separate than the new dash control unit?
I’ll open the panel with access to the back of my dash later when it warms up a little (go figure I’m in FL and it’s almost 32 this a.m.
I
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$800 dash control box and sensor upgrade kit……..single part number. If you replace your dash air box you need to make sure you have the correct part number. In my case I have the large A/C system, ….dash air with OTR air.
Your case would be small dash air system.. dash air with AUX air.
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