intermittent dash AC

[Guest Kent Madison]

On my 09 holiday rambler navigator Bismark 4 the dash AC works some times and not some times. I had the same problem with the wipers so I installed the 5V fix and that corrected the wiper problem. I am wondering if the Dash AC is also ran through the front CCM and if the low voltage that front CCM is providing could be part of the problem. I have checked all the fuses and they are good and I put in a new AC condenser fan a few months ago. Getting ready to travel south for a few weeks and would really like the AC working.  Any suggestion on if I need to add the 5Volt fix to the front AC CCM wires like I did for the wipers?

Thanks

[jacwjames]

What stops working, does the fan quit or does it stop cooling?

 

[Guest Kent Madison]

The fan blows but the AC clutch will not engage and the condenser fan will not run.

[jacwjames]

When was the last time you check the refrigerant pressures, if it is low on refrigerant the compressor will not run.  You should be able to check by jumping the low pressure switch. 

When I first bought my 2002 Windsor in 2008 the AC would not run.  I added one can of refrigerant and it took off and ran until ~2018.  I then had to add a little.  In 2021 I bought a cheap set of gauges to check and my neighbor who's a HVAC guy sold me a large canister of freon and help me check it.    Late last year the AC didn't cool as good as I would like so checked it a couple weeks ago and had to add a little.   At some point I may have to tear into it and look for a leak but adding a little every 3 years works for me.  It would take a lot of $$$ and to completely rebuild the system. 

 

[Frank McElroy]

1 hour ago, Kent Madison said:

On my 09 holiday rambler navigator Bismark 4 the dash AC works some times and not some times. I had the same problem with the wipers so I installed the 5V fix and that corrected the wiper problem. I am wondering if the Dash AC is also ran through the front CCM and if the low voltage that front CCM is providing could be part of the problem. I have checked all the fuses and they are good and I put in a new AC condenser fan a few months ago. Getting ready to travel south for a few weeks and would really like the AC working.  Any suggestion on if I need to add the 5Volt fix to the front AC CCM wires like I did for the wipers?

Thanks

On your coach, the HVAC gets power from the 30 amp fuse VCE5/6 on the large PCB in the FRB.  It is not powered through the CCM like the wipers.

[Guest Kent Madison]

PCB in the FRB????  Not sure that this means. Sorry

[Frank Bergamo]

Circuit Board in the Front Run Bay. Front Run Bay is located outside, under driver position. Good luck.

[Guest Kent Madison]

Thanks

[Guest Kent Madison]

it ended up being this temperature switch. Tapped on it and it started cycling like it should.  Thanks everyone for the help.

[Ivylog]

16 hours ago, Kent Madison said:

it ended up being this temperature switch. Tapped on it and it started cycling like it should.  Thanks everyone for the help.

I take the plug off that and insert a 15A fuse in the plug bypassing it so the compressor runs all the time. Yes, it will freeze up the evaporator BUT out West it usually takes 7+ hours before the airflow decreases enough to notice. In the East it can be 4-5 hours so I turn the AC off with the fan on high for 15-20 minutes (still get cool air as it defrosts) and then turn the AC back on…rarely have to run the generator,

[Guest Kent Madison]

I might try that if I need more cooling.  Thanks

[96 EVO]

That evaporator temp control switch failed on mine as well.

There was plenty of corrosion on the spade connectors.

[Guest Kent Madison]

Thanks

[Happycarz]

 

 

http://acmeairparts.com/rvacheaterparts.html
 

 

 

 

[96 EVO]

13 minutes ago, Happycarz said:

 

 

http://acmeairparts.com/rvacheaterparts.html
 

 

 

 

Yeah, I may need to tweak the adjustment screw on my new one.

Not looking forward to getting at the mounting screws, again 😣!

[Guest Kent Madison]

Thanks

[Happycarz]

As Ben said, you can adjust these thermostatic switches. GM used these same switches 50 years ago.
 
The capillary bulb on the end of the tubing monitors the evaporator temperature and applies pressure against a spring loaded set of contacts.  If the evaporator gets below freezing, the contacts open, turning off the compressor clutch. Once the temperature rises and the capillary bulb pressure drop below the spring rate, the contacts close and the compressor engages.

Using a small Torx, or even a flat bladed screwdriver, you can adjust the cycling temperature up or down from the outside of the thermostatic switch. But since the adjusting screw is out of sight, toward the firewall, it would be wise to unscrew it while trying the different adjustments. Once happy with the cycling temperature, screw it back on the evaporator box..

Yellow arrow points to adjusting screw on end of spring .

[Guest Kent Madison]

Thanks. I now know how to fix it if it acts up again.