Dash Air

[Jim Shaw]

The dash air on my 2003 Monterey, 350 Cummins has stopped working. I check it with gauges and have about 90 lbs on both high and low side which tells me it is not out of freon, but the compressor is not coming on and the condenser fan is not working. The green light is coming on when I turn the dash air on. Are there any fuses for the dash air that may be the problem. About the compressor, I am assuming it is not coming on since the pressures are equal, but I can't see the clutch. Any ideas will help.
Jim

[Edward Buker]

Jim,

If I am not mistaken, I think the switch to the compressor clutch runs the system. The voltage input may pass through a relay first. The condenser fans will probably be fired up by a trinary pressure switch on the high side. Until the pressure, due to the compressor operation, raises the pressure high enough on the high side, the condenser fans will probably remain off. Some systems turn those fans on all the time, so this is not an exact input, given I do not know your specific system. I think 90lbs, low and high side pressure should be enough to not have a low pressure cut off sensor stop the compressor from coming on. There are two wires that go to the clutch. You need to measure there and see if you are getting voltage with the dash switch on. You could apply voltage with a temporary  wire to see if the clutch and system is operational. That would confirm a wiring/switch/breaker or fuse issue that feeds the compressor clutch or the clutch itself.

I know that you indicated that you cannot see the clutch but in order to diagnose this problem I think you will need to gain access to the clutch wiring somehow.

Later Ed

[Butch Martin]

My Dash A/C on my 2003 Monterey is also not working.  Its on the list for my next visit to Beaver in Bend along with the leaking slide seals and seeping radiator.  Apparently the service techs have a lot of job security.  It will be interesting to see if my extended warranty is any good.

[Gerald Farris]

Jim,
There are a number of electrical problems that can cause the problem that you mentioned. There is a switch that senses the pressure in the high side of the system that will prevent the compressor clutch from engaging if the pressure in the system drops to low (around 30 PSI) in order to prevent the compressor from operating when the system does not have enough refrigerant.

The condenser fan is also operated by a pressure switch that will turn it on when the pressure in the high side is high enough and that will never happen until the compressor engages. So you condenser should not be running if the compressor is not running.

Your problem could be the control panel in the dash, a relay, the above mentioned switch, wiring, or the clutch coil its self although clutch coil failures are not common. The bottom line is unless you are familiar with diagnosing automotive A/C electrical problems you may need to see a professional unless you have a lot of time and patience to run the circuit to see where the open is in the circuit.

Gerald  

[Robert Mathis]

On the other hand, it could be something as simple as a loose wire. When they replaced my blown engine, the mechanic neglected to plug the compressor wire back in. I found it lying loose on top of the engine.

[Tom and Pam Brown]

i had issues with my a/c this spring.  Replaced the compressor and dryer.
if all else is working properly and there is enough freon in the system there should be a 12 volt reading on the single wire at the compressor.(with the controls turned on of course)

If you want to simply check the compressor for proper engagement then find a 12v supply(battery will suffice) and connect to the single wire on the compressor (unhook from harness) and it should pull in the magnets for engagement. do this without the engine running.

If the compressor clutch engages then it could be as simple as adding freon but do this with the proper guages.

My systme had a leak at one of the fittings and once repaired everything works great.

Hope this helps!

[JimCasazze]

Jim,
I too spent considerable time working on my dash ac this spring.  '99 Patriot Thunder, so not exactly the same. In any case, I uploaded quite a few pages of technical wiring drawings for ACME dash air to the website.  This would be a good place to start as you'll need a good diagram before anything will make much sense.  On my patriot, there were 3 relays under the dash itself (the diagrams are great, but they don't tell you where everything is located).  I had a burned up switch and a bad ground under the dash from which turned out to be the electrical issues.

Best of luck.
Jim

[Brad Burgess]

Hi Jim

On my last coach (not a Monaco brand) there was a sensor on the evaporator coil that would turn off the compressor if the evaporator iced up, usually due to very high humidity.  My evaporator coil was not iced up but the sensor itself had failed and prevented the compressor from engaging.  I am pretty sure that this is a standard feature on all dash air systems - might be worth a check.

Kindest Regards,

Brad Burgess
03 Monterey #800460

[Jim Shaw]

Thanks for all of the idea's, I have a lot to check. I'm sure one of the idea's will be the fix.
Jim