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Low A/C Pressure
Has anyone ever had a “low a/c pressure” warning pop up on the dash? I don’t get this all the time but every once in a while, it will appear on the dash and then usually after a short time it disappears. The driver’s a/c that is vented out from the dash works fine whether the warning is on or not. I assume this warning is only for the dash a/c and not the cruise airs, which are also working fine.
I don’t like to ignore any warnings but this one which is intermittent, does not seem to matter. Anyone have any insight into this?
Thanks,
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18 Replies
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OTR or driver’s air only?
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Uasuly that is a sign of low freon, if it is dash air only there is a sight glass at rear engine, if it is otr it has one in the a/c bay, check them with a/c on engine running.
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I had this on a. 2008 shell. Prevost checked it many times changed an expansion valve recharged it it was better but I occanisionsly had to turn off the dash AC for 5 minutes and reset it. I had an issue at Prevost in NJ they reset the multiplex system and all was well for a while. It may not be anything but a qurick. Lots of warranty hours and expense never really nailed it. For what’s it worth.
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Mike,
I have the exact same thing happening and getting it checked tomorrow. I’ll let you know, the assumption is it needs freon.
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I have had it happen and I know it is not freon level.
It could be a pressure switch issue, an expansion valve or something else but the easy way to verify freon is to look at the sight glass when the system is running. On OTR equipped coaches the normal status is the red ball will be centered in the lower sight glass on the receiver.
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I have full OTR A/C and mine comes on but I know it is low on freon. I had it charged last year and it lasted less than 6 months. Need to fix a leak. I know that on mine when the light comes on it disengages the magnetic pully on the compressor to prevent damage. I would think a bad sensor would cause that to happen as well cutting off A/C.
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The cooler the outside air is the more this will happen if low on freon, night time, rain, anything cooler
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I appreciate all the replies so far. I do not have OTR a/c but the dash a/c seems to work fine whether the light is on or not. Even when it does come on, it does not last long at all…maybe a few minutes at the most.
If you are having this issue Tom, I would be happy to hear what the diagnosis is after your coach has been checked out.
As always, appreciate everyone’s help and insight.
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Mike,
Mine was low on Freon and had a leak near the dryer. Leak fixed, new dryer, pressure tested with nitrogen, vaccumed and now working.
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I get that sometimes also. But I haven’t noticed any problem with the dash heat or AC when it is lit.
It may not mean anything. The Prevost manual, in describing the meaning of the warning lights, says about this light:
“When outside temperature is low or high, it is possible and normal for that telltale light to come ON. “
Having a warning light come on when there isn’t a problem doesn’t seem like a brilliant idea, but that’s what it says.
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Thanks for all the info guys. I suppose I can continue to monitor it and record when the light comes on and off and narrow down the specific details as you all have mentioned. Intermittent problems are always the worst to diagnose especially when the operation and function does not seem to be affected.
I’ve got the coach at Donnie Myers shop right now so I may get them to check for freon and possible leaks. I just hate the thought of spending money on issues that are not really issues.
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I was going to start a similar thread until I read this one after I noticed my light coming on today. It was 74 degrees outside and sunny. It came on after start up, and would not cool at all. So, I guess I’m safe to think its low on freon, based on Tom’s issue.
Really pissed me off, because I love my over the road air,BUT, I had to crank the Gen up and turn on Rvac and cruise air.
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Jerry,
My problem was dash air not OTR.
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OK Tom, adding freon to an OTR unit, is that something I could do, or do I need to take it to Prevost?
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If you have the gauges and understand how to charge an AC system you can do it.
However……….you have a leak based on what I think the light is telling you. If your system still has pressure you can recharge it but in a while you will need to recharge it again.
If it has no pressure then the issue becomes more complex because you still have a leak which must be repaired. the fact the system has no pressure indicates air could have entered the system so you are going to have to replace the dryer, and then you need a vacuum pump to evacuate the system, probably some nitrogen to charge the system to check for leaks, and then 24# of freon to charge the system.
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