What would cause this ...?

[Ray Davis]

Mentioned in previous threads (I think). Got dash air and cruise airs serviced at Prevost. While driving home from SLC Utah, dash air compressor seized up, and cruise airs stopped working.

So, but spent a week at Prevost, and just Monday they installed a new dash air compressor from Country Coach, filled the system with R12, and I drove off at 7PM.

Today (Tuesday) my neighbor takes off for what is to be a 6 week trip to the east coast. 4 hours into the drive, he reports dash air is no longer functioning. A little later, when he stops at a rest stop, he reports that dash air compressor (brand new), is seized up, breaking both fan belts to AC and alternator.

OK, twice now after a service? What would cause this. I mentioned at the time that they put R12 into the system, while there was a placard indicating it had previously been filled with R114. Could that be a cause of all this?

I'm hard pressed to believe that a new compressor would fail in the same fashion in 6+ hours of use!

Any thoughts?

Thanks,
Ray

[Just Plain Jeff]

My first thought is that, depending on how you wrote up the problem with Prevost, you got a 1 year warranty on their work. I would have a tough time understanding how a new compressor would fail under the circumstances you have described as well.

Prevost has a national network of service which can be accessed by any service center.

I can't understand the technical side of this problem based on what I have read, but the fix is on Prevost's side of the desk. If the problem was written 'a/c inop' they own it at no additional cost to you.

[Jon Wehrenberg]

Any compressor will sieze if it does not have lubrication, so I would verify when it was replaced the correct amount of oil was used. I would also make sure this is not a compressor clutch issue. The good news is Prevost will repair this at their expense, but it is reasonable for you to be asking hard questions to verify they really understand what they are doing.

On the other thread there was a lot of discussion in the past about problems Prevost was having with dash air compressors. There might be some additional information there if you do a search. I don't know if that will be a different issue than what you are encountering with a compressor from CC.

I have no clue about why the system uses the refrigerants you said. One is not commonly available, and the other has been an environmental issue.

One point you raise is that the AC compressor belts also drive the alternator (you did not specify if that was the house, bus or both alternator). The AC failure makes you uncomfortable, the alternator failure can shut you down. I would see what could be done to use belts independent of one another to drive those accessories.

Ray, take heart. You will get through these problems. When you do you will finally be able to enjoy a lot of trouble free miles but I think I can say we are all feeling your pain on this.

[Ray Davis]

So, got the coach back to Prevost today, and it appears that they are trying to track down "what" the problem is, rather than just throwing new parts at it. I didn't specifically ask, but it seems like they are covering this under warranty, but I guess these compressors are pricey, and they don't want to eat any costs that are not due to them.

So, I believe they are trying to do the right thing.

I spoke with a tech at Country Coach this morning though, and got some confusing information. First, the compressor they replaced, sits on top of the alternator, and is driven by the same two belts (main - alt - ac). This seems to be the 24 volt system only, as the 12V meters all indicate everything is fine, but the 24V system slowly drops as you drive, especially if you need to have lights on. I think carrying a replacement belt which goes only to the alternator is probably a good idea, although in thinking about that, I'm not sure if the belt adjustment is on the alternator, or on the AC compressor. I think it's on the compressor, so I'd have no way to tighten the belt.

There is some question on the previous coolant used. Because they thought that perhaps there was 134 used in this system (it was originally R12), they replaced the compressor oil with an oil that is compatible with both R12 and 134. I saw them putting this oil into the compressor (just when I arrived on Monday afternoon), and then I watched them put a lot of R12 into the system. (I still say there is a placard there though which indicates 114 was used, but it's barely legible, and I can't for sure say if it's 114, or 134. It doesn't look like 134, though)

I asked Country Coach if putting R12 into a system which had 134 in it would cause a seizure. They felt that it could. That would almost make sense to me. It was only after R12 was added to this system (now twice), that I had these problems. But, there was no indication that the system was converted to 134 (other than this slightly legible placard)

Now, just to make everything more confusing (sorry, that seems to be all of my threads!), in speaking again today with CC, they indicated that this compressor does not handle dash air, but only the galley and bedroom pieces of the Country Coach OTR. That's what they say, but I will indicate that they put R12 in this (supposedly OTR) compressor, and the dash blows colder?

I wasn't trying to get the OTR to work, as there definitely is some kind of logic board problem which prevents the OTR system from being engaged while the ignition is on. Several of the systems are now working backwards, i.e. on when the ignition is off, and vice versa. I don't remember it doing that until Prevost tried to make the galley and bedroom air work in the previous service.

I'm sorry if this is confusing. It's confusing to me, and obviously Prevost was very surprised when the bus showed up at 730AM.

Hopefully they will get to the bottom of it ...

ray

[Jon Wehrenberg]

Ray,

I am not aware of any refrigerant oils being compatible with both 134 and 12. If I'm wrong I hope someone corrects me.

FWIW, usually the refrigerant fittings on the system are refrigerant specific. For example, you cannot connect the 12 fitting with a 134 fitting so putting the wrong refrigerant in the system requires the technician to use an adapter or makeshift connection, a clue something is wrong.

Glad to hear Prevost owns the problem. It is annoying to you, but at least your wallet suffers no further damage. I would urge you get your guy at CC and your guy at Prevost to talk, and ask them both to keep you out of the middle. You will then be one more step removed from any liability in this situation. Neither Prevost or CC wants to eat this and if they can you are the one they will turn to.

[mike kerley]

Ray, Our CC AC compressor sets on top of the alternator. Alternator is used to tighten the belts that drives both. I have a set of belts that will just go just to the alternator to use when needed (thanks to Ken Robertson and Lester).

AC compressor on mine feeds three evaporator units. Bedroom, galley and dash. There are three switches up front for "ac compressor, galley fan and bedroom fan". If any of the three are on, compressor is active.

Ours was converted to 134 (and it leaks) but it holds a charge for about 30 days. I purchase freon in the 30lb cannister and recharge as needed. It is getting worse (the leak, that is) and i must have a fitting loose somewhere. I'll get around to digging for it someday.

[Ray Davis]

Sounds just like my system. It's good to hear that the tensioner is the alternator, I'll grab a set of belts to work in that mode.

As best as we can tell, a previous owner introduced something other than R12 into the system. The connections on the compressor were not changed, although there is this barely legible placard saying something about 114.

Prevost is telling me the issue is line contamination, and are attempting to get it thoroughly cleaned, and back to R12. It seems that if the refridgerant was changed, the PO did not complete the task which should have included changing O-rings and the adaptors onto the compressor.

The tech did show me the bottle of oil he was putting in the previous compressor, and it did indicate R12 and 134 compatibility. I'm not sure of the name of the oil, but I can check if you'd like?

[Ray Davis]

Mike, do you know the belt numbers on the belt which goes only to the alternator?

[mike kerley]

Ray, the short belt is a NAPA 5L680. You'll need two and matching sizes are important.

Mike

[Orren Zook]

On smaller diesel engines (a 7.3L Ford to be exact) over charging the dash system can cause the air conditioning compressor to sieze. At idle the engine has enough torque to allow the crankshaft pulley to burn through the fan belts when they cease to turn. I would think that an 8V or series 60 would also burn through a selt of belts with ease.

[Ray Davis]

Well, in this case, it seems the original issue was caused by R12 being put in a system, which contained "something else". There was a sticker in the normal location, which indicated that some other refridgerant had been put in the system. But, R12 was introduced, and these two things didn't intermix at all well. In fact twice, with taking out two compressors.

I got the coach back Thursday. Drove it for about 1.5 hours enroute home. I took it back to storage today, another 1.5 hours, and the AC worked great. Am I 100% confident that the problems are solved. Not on your life. But, they evidently cleaned the system really, really well, this time, and then put R12 in it again. They stated that the current hoses etc were not designed for 134, and that replacing the whole system would be $5000-$8000. More Lew Bucks than I have in the bank!

So, I've got a bus that seems to work again. I'm scheduled for POG2 in October, and I'm praying it's gonna be a lot cooler than now! :D