dash air recharge

[Doug Allman]

Anyone know the amount you are supposed to purge the system down to, microns, prior to replacing refrigerant?  2004 Marquis C12.

Then how much 134A does it take, lbs, to recharge a total system.

We have installed new compressor & accumulator and have system on nitrogen now testing for leaks. Replaced all the o rings also.

[Gerald Farris]

Doug,
I normally evacuate an A/C system for about 30 to 45 minutes. This will yield a vacuum reading of usually about 28 inches. If it holds that vacuum for an hour or longer, depending on how big of a rush you are in, then recharge the system. I would imagine that your dash air system has the same capacity as my coach's, and that is 3 pounds (four 12 ounce cans). If you replaced the compressor and dryer, I personally would add about 4 ounces of PAG oil to the system before recharging it.

Gerald 

[Doug Allman]

Gerald,
Thank You, I will pass info on to my a/c man. We have the PAG oil so will add. We checked new compressor and it had PAG oil in it (loosened plug on bottom to check).

[Edward Buker]

It is an era on our coaches when the dash air systems are old enough to expect compressor issues. I'm in the process of changing out my compressor and receiver dryer at the 14 year point.

This is the compressor PN information from my 2002 Marquis and some additional lube info. The original unit was a Seltec PN488-46120 and may be one of the common units used in this era Beaver coaches.

http://www.buyautoparts.com/buynow.asp?partnumber=60-02168_NC

There is an info sticker on the rear cover with PN, Comp Type, Refrigerant, etc but the actual usable PN info is just a number sticker on the top of the housing. Seltec and several other brands are now consolidated under Valeo and this Seltec compressor now has a Valeo PN of 103-56120. It looks to be exactly the same and the good thing is it appears to be of high quality and is manufactured in Japan.

As Gerald points while changing the compressor and receiver dryer out, you usually add a few ounces of oil. The information on the back cover label of the compressor will tell you that it comes with a 6oz (converted from 180cm3 on the label) precharge of ZXL100 oil which is not readily available. I asked the compressor part supplier what to use and they said PAG 100 oil is compatible. One would think that from the ZXL100 oil label.

I checked with Valeo tech support to be sure, and although it is confusing, the ZXL100 is actually a PAG46 oil. The 46 is the viscosity number and that is the only viscosity Valeo considers compatible with the compressor design. Given the number is the viscosity, that is a significant difference, so it is important whether you do the work yourself or you have a shop do it, be sure they are aware of this issue and use PAG 46 oil if you use this compressor. Hope this helps.

Later Ed

[David T. Richelderfer]

I went out yesterday and found the recharging port for my dash air.  It is above the generator - 15 inches or so above the top of the generator and slightly street side of center.  It is not easy to reach, I might add.  It cannot be seen except by using a flashlight and small mirror... holding the mirror to be able to look up behind the nose cap.  So today I went and purchased a couple cans (19 oz. each) of R-134 to put in.  I attached the bottle to the port and went in to start the coach.  Now when I turn on the dash fan, temp to full cool, and push the a/c button, it's all dead.  I checked power in the left bus bar in the power bay - 16.75v.  I turn on the key and right bus bar shows 16.75v.  The fifth wire above the crossover solenoid on the ignition side of the bus bar is labeled "a/c" on the schematic on the door - it shows 16.75v.  The dashboard lights all appear to work fine.  But the fan switch doesn't turn on the fan.  Pushing the a/c button doesn't light it up.  It all worked Labor Day weekend.  Is there a fuse behind the dash plate for the fan switch, etc.  Interestingly, on the Labor Day weekend I found a flat washer and a short screw with attached lock washer on the floor under the steering wheel.  What do ya think?  A loose wire?

[Edward Buker]

David,

It would be hard to know without tracing the circuit where the fault lies. You could check the wiring on the back of the control panel to see if all plugs are well seated. The circuits in the side panel electrical bay, where the busses are, use thermal breakers. If you have voltage there for the dash air breaker on both sides, you should have it at the back of the dash air control panel. There is a fan speed resistor set below in the front of the coach, to the left of the steering box on mine, which is bypassed on the high fan speed position. You could check there for voltage also.

I do not know if you are using a digital volt meter but 16.75 V is well above what is expected. Not sure if it is a meter issue or not. Take the meter to your car with the engine off just sitting and it should read about 12.6-12.8V, if so something is off with your motorhome charging system. If the meter is working properly then check at the coach batteries, if they are at 16.75V ,you would be boiling out the electrolyte rapidly. If so you should shut down the charging system until it can be corrected.

Later Ed