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Topic: Dash AC Troubleshooting (87 GV) (Read 591 times) previous topic - next topic

Dash AC Troubleshooting (87 GV)

My dash blew cold air when I bought the coach over a year ago. Once I realized the compressor belt was squealing like a stuck pig I quit using it. Supposedly the AC was recharged just prior to my purchase. I fixed the squealing tonight and tried the dash AC but it only blows hot hair. Here's what I know:
    • The clutch on the compressor is engaging and the pully face is spinning and looking good
    • The cold line out of the compressor is cooler than air temp but not real cold
    • The cold line going into the box at the front of the coach (heat exchanger? radiator? Not sure what it's called) is ice cold
    • The hot line going into the compressor is very hot (can barely touch it)
    • The hot line exiting the box at the front of the coach (return line for AC) is warmish but not hot like it is at the compressor
    • The coolant lines on the other side of the box for the dash heat are hot like you would expect
    • If I turn the switch on the dash to "AC" it blows hot hair
    • If I turn the switch to "Heat" instead, no air comes out at all
    • If I turn the switch to "defrost" hot air comes out of the dash vents like you'd expect
    [/list]

    I haven't opened up the aforementioned box at the front of the coach but there appear to be two fans. One on each side that correspond to the AC and engine coolant lines that enter the box on either side. Is it possible there is some sort of diverter door inside the box that is possibly stuck to one side?

    In attached pictures, the two lines entering the box on the left side are the coolant lines and the two entering the box on the right side are the AC lines.
    1987 Grand Villa ORED
    2001 U320 4010

    Not all that wander are lost... but I often am.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #1 –
    The first thing you need to do is hook up ac gauges to see what the pressure is. It could have a clogged expansion valve.
    previous 1984 35 ft ORED 250 HP 3208 Cat       
    previous 1998 40 ft U295 CAI 325 hp Cummins
    previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
    1999 Mazda Miata
    Ron, Nancy, Tipper the cat, Max The dog
    1997 U 270 36 ft build number 5174 8.3 Cummins

    Re: Dash AC Troubleshooting (87 GV)

    Reply #2 –
    In the first picture that shows the coolant lines to the heater core, at the top of that back line is a valve to turn off the coolant flow to the heater. Make sure that is working and stops the flow when not in heat mode.
     It sounds like the ac is working,  it's just not getting the air flow right. Probably worth popping the cover on that box to see what's going on.
    1991 U300 Side Aisle 6V92 Silver #3897
    2004 U320 40' #6246

    Re: Dash AC Troubleshooting (87 GV)

    Reply #3 –
    Quote from: kgrover –
    In the first picture that shows the coolant lines to the heater core, at the top of that back line is a valve to turn off the coolant flow to the heater. Make sure that is working and stops the flow when not in heat mode.
    Thanks, this was at least part of my problem. There is basically a bicycle cable attached to the horizontal temp adjuster pictured below and that operates the valve you mentioned. It is no longer opening/closing that valve so it was stuck on open and the hot air was basically overpowering the cold air. I pushed it closed with my finger and now I'm getting cold-ish air that my laser thermometer reads in the mid 50 degrees. Ambient temp is 68. So it's still about 10 degrees off of where it should be.
    1987 Grand Villa ORED
    2001 U320 4010

    Not all that wander are lost... but I often am.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #4 –
    Next step would be to get some AC gauges on it. You can borrow them from AutoZone, or pick up a set on Amazon
    1991 U300 Side Aisle 6V92 Silver #3897
    2004 U320 40' #6246

    Re: Dash AC Troubleshooting (87 GV)

    Reply #5 –
    Quote from: kgrover –
    Next step would be to get some AC gauges on it. You can borrow them from AutoZone, or pick up a set on Amazon
    I ordered them earlier today  ^.^d
    1987 Grand Villa ORED
    2001 U320 4010

    Not all that wander are lost... but I often am.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #6 –
    I'm somewhere around 10psi low on both sides of the system. Readings taken at 68 degrees ambient temp. At some point this was converted over to r134a.
    1987 Grand Villa ORED
    2001 U320 4010

    Not all that wander are lost... but I often am.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #7 –
    Low on Freon.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #8 –
    So a year ago it was charged and worked. Nice that it has a little charge but you need to kinda start over IMO if you plan o get to a reliable working system.
    You know you have a leak.
    The is a great time to change the dryer.
    This would also be a great time to have a service machine to be able to recover any Freon and charge with a known value. Not having any history doesn't help either.
    Adding a leak detection dye will help troubleshooting.
    I would look the system over closely preferably before anything has been washed and look for evidence of oil wetted lines fittings and the compressor. Indicating a leak. If you find anything to have a reliable system it will have to be addresses

    Re: Dash AC Troubleshooting (87 GV)

    Reply #9 –
    Quote from: Elliott –
    At some point this was converted over to r134a.
    I would want to see if they just put the conversion fitting on or actually converted the system. R134 systems have a Hi pressure switch on the high pressure side. A lot of R12 didn't. If it has it great, but if it doesn't I would add one. Just goes in series with the low pressure switch. Too low of pressure and the low pressure switch go open. Too Hi and the Hi goes open. One or both can be Binary switches also. Example would be the low pressure going open below 5 psi /closed above and if the pressure gets above 65 psi goes open being too hi for the low side.
    Another consideration in these conversions is the condenser. R134 need a bigger condenser. If you have a round tube condenser it's a great time to replace it with a flat tube and this will give you the needed size increase in the same area. Evaluate the condenser fan too.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #10 –
    Good advice from Scott. 

    Personally I would just add freon now and see if it works at least good enough until back at home and then dig into it there.
    Dave and Kelli
    1997 U295 40' Build #5188 CSGI
    1995 U240 36' Build #4621 SBID-SOLD
    2006 Jeep Wrangler Rubicon

    Re: Dash AC Troubleshooting (87 GV)

    Reply #11 –
    Both dsd and Dave have good suggestions. It just depends on how much work you want to do on it. I would either get some refrigerant with UV dye in it, or some other way to get the UV dye in it. That would help find any current leaks or leaks in the future. The pressure your seeing isn't terrible at 68°. It doesn't seem like it's that low. Definitely low, just not super low. You could stick a can or two of R-134a in it and keep using it for a year or two while you plan the upgrade.
    1991 U300 Side Aisle 6V92 Silver #3897
    2004 U320 40' #6246

    Re: Dash AC Troubleshooting (87 GV)

    Reply #12 –
    Thanks guys, I grabbed a can of r134a and will shoot it in tomorrow if this rain stops. It is just normal refrigerant with no stop leak added but I am curious what you all think of the refrigerant that comes with the stop leak included. I have read mixed reviews on the Internet, seems to me it could clog the expansion valve.

    1987 Grand Villa ORED
    2001 U320 4010

    Not all that wander are lost... but I often am.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #13 –

    So static your at 10/10 psi. Good working numbers will be 20-30 / 200-400. One can will put you closer to the right direction but I'm doubtful it will be enough to close the low pressure switch enabling it to even operate. I've never used but seems I recall something like redhead/ or something like that used
    Red angel
    https://www.amazon.com/Angel-Stop-Conditioner-BlueDevil-Products/dp/B01LRHWHVE?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A2J6AQRUR1XPU9

    As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

    Re: Dash AC Troubleshooting (87 GV)

    Reply #14 –
    There may be simple hose clamps on the hose ends. Snug them up and a take a peek with some spray bubbles  as you add a can of charge.
    The sealant style will help if you're lucky.  You should need about 4-5 cans to get near 210# and 46#
    If the pressure spread is way over this. , under 30, Change the expansion valve.
    Way under , like  over 60 on the low side  , change the valve.
    But short story is that if you have some
    pressure spread , it will blow cool .
    Foregot!! All of the under dash ducts have to be connected and leak free . Tape them up with vinyl tape .
     

    Re: Dash AC Troubleshooting (87 GV)

    Reply #15 –
    I don't remember for sure but the earlier ORED had the condenser mounted between the fan and radiator. These were prone to get plugged with oil and dirt.
    previous 1984 35 ft ORED 250 HP 3208 Cat       
    previous 1998 40 ft U295 CAI 325 hp Cummins
    previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
    1999 Mazda Miata
    Ron, Nancy, Tipper the cat, Max The dog
    1997 U 270 36 ft build number 5174 8.3 Cummins