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Message |
Prevost83 (67.137.160.130)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 07, 2004 - 5:03 pm: | |
Anyone know approximately how much freon the ac unit in a 1983 Prevost LeMirage would hold. It is 134 A and I do not have a manual for it. That also brings me to another question, does anyone have a Prevost manual that could be photocopied, I would be willing to work something out with anyone who would have a manual I could borrow for a few days to copy? Anyway, the AC has been charged but does not seem to blow as cold as it should and the mechanic that charged it was wandering if I could find out exactly how much it was supposed to hold as he is going to vacuum the system down, check for any leaks and what not, and then re-charge the system. Thanks |
James Maxwell (Jmaxwell) (66.81.60.39)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 07, 2004 - 6:30 pm: | |
Approx. 30-35# if it is whole bus A/C, based on similarly sized systems in other buses. I am not specifically familiar with Prevo but if it was recharged to approx. correct charge level, have u checked unloader settings, superheat at the x-pansion valve, and the hot water reheat valve for full closing. Another problem may be a dirty evaporator coil. If the system is under charge, the best method to find a leak is with a halide or electronic detector or u could add an inert dye that changes the color of the oil and maybe visualizes the leak to u. Much easier to detect leaks under pressure than in a vacuum. |
Bruce Henderson (Oonrahnjay) (208.34.240.40)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 07, 2004 - 7:26 pm: | |
__. Yes, it's much easier to find leaks under pressure than on a vacuum but drawing down to a vacuum is a standard procedure for A/C work. It has a number of advantages - it allows you to judge the size of any leak (based upon how soon the vacuum leaks away) and allows you to start with a "clean slate" for the addition of coolant to a system. One thing that I've seen done is vacuum on a system, and - when a leak is confirmed - only about 1/10th of a full charge is put in with leak detector dye. Once the place of the leak is found, the leak can be fixed and a full charge installed. This is one of those "full procedure" things that usually works very well.
__. Also, it would be very rare for an '83 system to have been designed at the factory with R-134a (is this a standard, factory system or an add-on?). For systems that were designed for R-12 ("Freon") and converted to R-134a, you'll find that performance is not as good as you'd expect. (R-134a isn't as good a coolant but it's much more environmentally friendly and a system that's designed for it from the ground up can be pretty close in performance to a Freon system.)
__. James is also exactly right about places to check. I'd also check for leaks and possible hot air mixing in ductwork, too (in addition to the hot water shutoff -- which, if it's not closing all the way -- can result in a LOT of heat being put into the A/C.
Good luck, A/C can be handful to troubleshoot. Bruce Henderson, Wallace NC |
Ray D (68.123.111.104)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 07, 2004 - 10:27 pm: | |
You can by the manual on CD from www.coachinfo.com
Have a Prevost day,
Ray D |
Stephen Fessenden (Sffess) (65.130.19.245)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 07, 2004 - 10:58 pm: | |
It has been suggested to me that a very small amount of R22 (after vacuuming) will make it possible to use old fashioned leak detectors which don't work with R134a. Not sure it is legal, and I have not done it, but it should work. Best auto AC leak detection I had was by a shop that put in a small amount of R12 ( in an R12 system) and then ran the system to distribute the R12, then stopped the engine and compressor and pressurized to operating pressure with nitrogen. They found every little leak because there was no airflow from radiator fans, Alternator cooling fans, condensor and evaporator fans to dilute the leak. Unfortunately that shop was bought by people to lazy to continue the practice. If your system was originally R12, why wouldn't it be legal to vacuum it out, add a little R12, find the leaks, remove the R12 into a legal R12 recylcling system and fix the leaks, repeat the leak check with R12, draw off R12 and add R134a or Freeze12. I have also been told it takes less R134a than R12 in an R12 system. You should be able to pressurize with pure argon from a mig welder tank if there is no nitrogen is readily available. Argon also comes from the atmosphere by liquification of air and does no harm to the atmosphere when it is put back in the air. |
Bruce Henderson (Oonrahnjay) (208.34.240.49)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2004 - 12:37 am: | |
__. All of Stephen's posts are very appropriate -- it's VERY useful to be able to use a "sniffer" to find leaks. Dye can hide behind bends and bulkhead entries (right where it will be likely to leak anyway).
__. The problem with R-12 (I'm not sure about R-22) is that it's getting to be very expensive and hard to find. That's what the government authorities are trying to make happen. So, if you can find it, it's a lot of $$$$.
__> But, again, Stephen's post show a lot of knowledge and logical thought so - if you're less experienced with A/C - take some time to think his points through.
Good luck, Bruce Henderson, Wallace NC |
Mike T (66.82.9.35)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 13, 2004 - 8:59 pm: | |
I have trouble keeping my prevost charged and I found out why. I was at Prevost, Mira Loma and the guys there showed me how the Aeroquip lines built for R-12 don't hold 134-A. Soapy water test shows tiny bubbles leaking right through the fabric. I would love to know the solution if there is one besides replacing all of the lines. |
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