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OTR Air Dash Light ?
My OTR Air worked Awesome when I got the Coach. And It will still work , But is intermittent. There is a Amber A/C light that comes on the Dash just under the Heat / AC Switch. Second Light down. The top one is for the Heat.
When the amber light comes on. I can hear a faint click behind the lower dash panel near the floor on the passenger side. And the Air seems to quit.
Does anyone know what this light means ?
Thanks in Advance !
Rocky
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36 Replies
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There should be two lights. Just to avoid confusion I will attempt to describe both.
One indicates when the heat valve is open to modulate the cold air coming through the evaporator. It is not uncommon to see that light cycle on and off. Usually if you set the temp control to the coldest and let the coach interior get cold, when you turn the temp knob to a higher setting you will see the light come on to indicate the system is adding a little heat.
The second light is an indicator of high pressure in the system and when that comes on it usually is an indication the condensing unit fan(s) are not working. It is possible for that to cycle also. When it comes on I believe the compressor stops working. When the system pressures drop to an acceptable level the compressor kicks back on and for a while, before the pressures build up again the system functions. That is akin to using the thermal overload on an electric motor to control the motor operation.
If that is the problem it could be anything from a tripped circuit breaker for the condensing unit fan(s), a failed motor, a bad relay. Whatever the cause it is easy to check. Turn on the OTR and if the condensing fan is not running that is the problem.
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Ok , Where is the condensing Fan ?
Thanks,
Rocky
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The fans are in the port and starboard bays. With the coach running and the OTR running switch to heat. Go to OTR bays and open the doors. As others often preface their remarks with “can’t remember” so don’t hold it against me, I do the same. The heat is on I think the starboard side and the cool on the port. Does ot matter though you will check both.
Check to see if the heating fan is running. If yes switch to cooling and check if the cooling fan is running. Both must be in running condition.
Turn coach and heat and ac off.
You will have to be mechanical and somewhat competant/confident in examining the fan motor for what I describe.
A small pick with a right angle tip is a useful tool, aswell as a brass pin with radiused ends (sharp ends might fracture the carbon brush) and a plastic hammer to tap on the brush end to be sure it is seated in the pocket. EASY DOES IT or else.
Check the brushes of each motor(heat and AC), 4 each. They sometimes stick in their pockets. (very carefully free them to slide in the pocket, if necessary, caution not to chip or damage them) the brushes need changing if their top surface is below the top edge of the pocket. To change the brushes the fan and blower need come out of the compartment. Some special small wrenches and a magnifying glass will be needed as well as a full vocabulary of cuss words.
The brushes stick because as they run on the armatures they wear and so doing generate carbon dust that contaminates their operating area and if you run down the road in wet weather the dust becomes paste like and siezes the brushes in their pockets.
If you like mechanical work this is a good project for you and it will save money. Prevost mechanic will acknowlede several hours required.
Well your just checking now. If you find stuck brushes and have freed them start the coach again and test the heat and AC again. You may be home free.
If this did nothing for you, do not dispair, you should know how to do it anyway and you will know if you need new brushes or not.
So, still no heat or AC, next go to the box on the starboard side of the coach with coach and OTR off remove the cover from the relay/fuse box and then with a volt meter go through the circuit and check for voltage at the various points with the units on, testing the circuit breaker has not poped (doubtfull), testing the two relays (likely failure point). Basically your tracing through the maze of wire making sure the supply voltage is moving along the circuit from its source through all components to the motors. If you didn’t know, the relay is activated by the low amp switch to transfer the high amp load of the motor circuit. You have two circuits. The switch circuit and the load circuit. That sounds simplistic, but that in fact is what you are doing.
These relays are an important spare part to carry on the road. These relays are from Prevost or are used on lift trucks for an after market part. Prevost Pt No. from Prevost. Generic No. Solenoid SNLS-24B (24B =24V….12B=12V). My coach is 24V. this part may be 24V across the board, don’t know, check your voltage at the terminal.
I purchased solenoids with good results from HGM Lift parts,inc., Pt.No. PLSAS-5401A ARO $150 ea.
hgmforkliftparts.com
Rather difficult to describe this all in writing to someone I don’t know, but for what it’s worth, you can do it.
If you want more, ask away, but I don’t know much more if any.
I do think I have described this in a previous thread, but I have no idea how you will find it.
If none of the above fixes your situation, it is still good to know these things that will probably affect you on the road.
Check to be sure the compressor clutch is turning, if not look at wire connections.
Possibly refrigerant is marginally low.
Anything else ask Jon, he took the Prevost course for OTR offered by Prevost.
JIM
Understanding your coach gives peace of mind on the road!
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Jim,
Thanks so Much for the detailed descriptions. I started the Bus today turned the AC on and opened the door 3rd bay back on the Passenger side and The fans were running. I sit in the Bus for a couple of Hours , And the AC never failed. It will wait until I am in Traffic in 90 Degree weather most likely. But I noticed the inside of that bay is rather Dusty and Dirty. Time for Some Spring Cleaning. I need to get a Brush and wash out the fins on the condenser radiator I guess You would call it. I removed the cover of the Box inside of that Bay. And found (2) 4 post relays . Like the old Ford type.
Are these the ones that You are talking about that are Problematic with Age ? I had to change one like that to get My interior lights fixed. And in the process , I found out that there are a few different kinds that look the same.
If You can find the information on them , It would be Greatly Apreciated !
Sincerely,
Rocky
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The relays you describe are not totally reliable. It would not hurt to carry a spare.
If I had to list the items I would look at (aside from freon charge) here they are:
Make sure the fans are running.
If the fan is not running check the fan circuit breakers, the relays, the brushes if everything else checks (you have power to the fan motors) and make sure the clutch is engaging.
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Read my previous post again for answers to your subsequent question and to see additional added information.
JIM
It is easier to say NO, yes means MORE WORK!
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Just reinforcing your post Jim. The items I mentioned were in approximate order of frequency of problems I have been involved with.
Prevost has an excellent webinar on the OTR AC system and it is a great way to spend a little time for background information before calling a tech to service the AC system.
Access the webinar throught the Prevost site, commercial side.
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My Prevost Installed OTR blower continues to shoot the 120 circuit breaker located 3rd bay from the front drivers side. I have replaced the breaker with a brand new one and the problem continues. Any one had a similiar esxperience and can give me a suggestion on what to do next ?Relays? The blower will attempt to run and stops almost immediately.
The compressor works fine and I can still get cold air thru the dash vents. This is the blower motor that circulates the conditioned air thru out the remainder of the bus.
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Sounds like the motor is pulling too much amperage and tripping the breaker. I would start with the motor and check the amp load. There may be a motor in your future.
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Roger,
Does the motor turn the fans freely? How are the brushes?
Do you have a clamp on meter so you can read the motor current draw to compare to the breaker? Do not rule out a new breaker being defective.
The breaker should be handling the 24 volts for the motor. You said 120?
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I noticed the second time in the past weeks that mine does this also. If I have run the cruise airs at site then leave and coach is already cooled down inside light will flicker and let you know it’s adding heat. . It will also ficker on and off every once in a while while driving down the road when it is really cool inside. I think one of the good folks on here said it does it every once in a while if things (condenser) is freezing up. I always heard it was low freon level but who knows. My coach is Haunted! Mine is 91 with 8v92a.
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Mine does it also and lights the Webasto light on the dash, but the Webasto wouldn’t be firing, just turning on the pump to circulate the coolant when it calls for some heat.
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Rather than start a new thread, thought I’d tag to this one.
We’ve owned our rig 6.3 years. Today, for the first time, the over the road ac did not go on when switched to do so. I have read all the posts on this that were reported for the past year. We got the yellow light on the dash below the switch with the image of a connecting rod imbedded in it.
Based on the charging connections on the compressor, we are 134a, not r12. I have not tested the charge yet.
From prior posts, I’m familiar with the failure possibilities of 1)low charge, 2) circuit breaker popped, 3) failed solenoid (relay), and 4) blower motor brush stuck in pocket or worn.
What I have done:
A) Inspected and tweaked the motor brushes that are visible (two out of four) on the heat side and the ac side. Found no evidence of failure being sensitive to “stuck in pocket”, worn down as to not have spring pressure against them, spring bottomed on pocket.
B) Spun the blowers/motors on both sides by hand, and found that they spin freely.
C) With everything shut off, checked for voltage inside the white plastic box located inside the condenser bay (starboard) side. There was none anywhere. The content of this box includes everything pictured in a previous post, plus a circuit breaker, which was not popped, located in the upper left quadrant of the white box as you look at it.
D) Started the Detroit (60 series), switched to heat, the blower ran normally. Then switched to A/C, no blower action, and no voltage entering the white box.
So, does anyone know where to backup to next to find voltage to feed the white box? Could low 134a charge cause no voltage? Is somethiong going on with the compressor to trigger no voltage? Nothing is popped in the electrical compartment below the driver, and couldn’t see anything on the schematic inside that door that was relative.
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Dan,
Brother Jay still into coaches? Maybe see you both at Branson?
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