Auto airconditioning

[banjo5491]

I have a 07 tour with a 400 hp Cummings engine. My problem is with the auto air. The Freon is good but the compressor doesn?t seem to be engaged. Has anybody out there experienced this problem and what?s the corrective action?        Thanks!

edit by staff - changed message icon to topic solved

 

[Willandgiselarv]

Usually if Freon is low the compressor won't start to engage. How did you figure that Freon level is Good?
The sight glass?

 

[Neal]

We  had the  high pressure switch fail open, probably due to one of the condenser fan motors going bad.
If I remember correctly, both fans are supposed to run any time the compressor is calling for cooling.
We installed both the switch and fan, new. We did get a generic fan and adapted.

 

[cerd]

There's nothing really specific about diagnosing AC systems. Check the high and low pressures with a manifold gauge set while the engine is running and the AC turned on high, recharge if low. Diagnose further if it is empty because you may have a leak somewhere. I have had gaskets go out on my compressor connections and I have also had schrader valves leak on the test ports. Check the function of the high pressure switch and make sure the clutch is getting power to turn on. Once you do a few, A/C is really easy to diagnose and fix.

 

[John Canfield]

^^ Yup ^^

I've had a packed up dryer/filter, leaky Schrader valve and a leaking compressor seal - spread out over several years. My last dash air problem was a leaky duct box, that took quite a while to diagnose. Winnebago factory service finally found the problem.

 

[cerd]

^^ Yup ^^

I've had a packed up dryer/filter, leaky Schrader valve and a leaking compressor seal - spread out over several years. My last dash air problem was a leaky duct box, that took quite a while to diagnose. Winnebago factory service finally found the problem.

When I was finding my last leak, I added just a little bit of freon, and sprayed soapy water on all of the joints. That was how I found the leak on the connection to the compressor behind it. An ounce or two goes a long way to pressurize the system for leak testing.

 

[catblaster]

you might want to check fuse/breaker for AC to see if compressor clutch is even getting power. Then check high/cutoff for power or bypass with jumper, The condenser fans on our luxor only can on when pressure built up enough to trip switch....along with the items everyone else has had our compressor "O" rings were of the older lower pressure type, schrader/charging valve leaking and factor installed condenser filter/dryer was installed backward.

Basically check for power first then for a defective compressor clutch....that is assuming the belt is still on installed.

 

[sandpsycho]

Hi from the new guy here.

My dash AC was doing the same thing. No compressor clutch locking up and the condenser fan not coming on. It was a bad thermostat, if it doesn't pass voltage (close the circuit) the above items will not kick in and no cool air.  It's a small metal box with 2 wires and one metal wire probe that goes into the housing where your evaporator and heat core are located. Easiest way to check it is pull the 2 wires put a 30 amp blade fuse in the wire connectors making sure you have good contact and turn the ac on. The thermostat is meant to shut down the compressor before the evaporator starts to ice up. On my moho this part right behind the front hatch above the generator.. You can bypass the thermostat and get on with life but you will have to pay attention for frost or icing. Not a real issue in the southwest where it's dry and stupid hot but more humid parts you'll be turning your ac off and on and your temp dial more to control this.

This is the one with the same specs of my original and give you an idea what to look for
https://www.napaonline.com/en/p/TWRMEI1332

Good luck

 

[John Canfield]

Welcome and thanks for the helpful info!

 

[banjo5491]

Freight liner found a leak in one of the lines that was also plugged. Thanks for all of your input!

I also printed your suggestions and showed them to the service manager who found them quite helpful.

 

[John Canfield]

Great! Thanks for checking in with the results.

 

[mickey53usa]

John,

Can you explain the leaky duct box? As you know, I have had issues with my dash air for the last two years and $2K plus has not fixed it. You may have found my answer.

(KG5UMH)

 

[John Canfield]

I'm ashamed to admit I have no idea exactly what factory service taped (or used mastic) up to fix the problem. The symptoms were warm and humid air periodically coming out the dash vents. I was at my wits end to get to the root of the problem, I insisted there was a problem and by golly Winnie stepped up to the challenge 

 

[taoshum]

I think I have the exact same issue.  When we start out the AC works great but after a while it stops blowing cold air.  It's a long story... Anyway, one bright soul told me it might be the thermostat or the wires near it or a pressure switch.  So I pulled the wires off the thermostat and plugged it back in and then the AC started working again.  So I probably need one of the thermostats.  I found the A46-3122 replacement (i was worried it would be unavailable) but I haven't bought it yet.  I went back to the RV to see how much of a job it will be to replace it...  Then I noticed the small tube!  I can get the unit off the firewall, wire, etc but getting that small tube out of the black box (evaporator?) and the new tube back into the right place might put me "over the top"!

One posting mentioning taping the tiny tube to the cold side hose/tube fitting?

Or, Just bypass it and short out the two cables?  Out west here, probably won't see icing very often?  I do recall '67 Dodge I had would ice-up if the conditions were such.

OTOH, I'd like to replace it, just because.

Maybe someone can lead me/us thru the process or at least tell us how much work is entailed???

Thx, G.