Chassis AC not working...

PeterB · 07-13-2011, 11:27 AM

Hi All,

I have a 2002 Damon Daybreak with a workhorse chassis and during our last trip the A/C just quit and started to blow hot air. Even when I selected the vent setting I was still getting hot air. I finally turned it off and had to start the genny and run the ceiling a/c to cool things down. Does anybody have experience with a problem like this and what the cause may be?

Thanks,

Peter

howdja · 07-13-2011, 02:32 PM

Peter, there could be a lot of causes for this problem. From a faulty AC compressor clutch to low freon. Best thing to do, if you are not familiar with AC systems, is have a qualified AC mechanic check it for you. It shouldn't cost very much to diagnose the problem.

She and I · 07-13-2011, 03:05 PM

Quote:

Originally Posted by PeterB

Hi All,

I have a 2002 Damon Daybreak with a workhorse chassis and during our last trip the A/C just quit and started to blow hot air. Even when I selected the vent setting I was still getting hot air. I finally turned it off and had to start the genny and run the ceiling a/c to cool things down. Does anybody have experience with a problem like this and what the cause may be?

Thanks,

Peter

Hi, Have you checked fuses?..Can you hear the A/C compressor kick on?.If the compressor is running.. check vaccum hoses ...Start there and let us know...Oh forgot Welcome!
Richard

pkmesser · 07-13-2011, 05:11 PM

After the engine is warmed up, check the heater hoses that goe to the heater. The heater control valve may have failed, and be passing hot coolant to the heater. The AC cannot overcome that amount of heat. If that is the problem, the valve can be somewhat expensive. I put a ball valve inline, next to the heater control valve. Turn it off in the warm seasons, back on in cold seasons.

ga traveler · 07-13-2011, 05:32 PM

the most likely reason is low freon. you have a low pressure switch that cuts out the compressor if the freon gets low. I would start there.

Full-Timers · 07-13-2011, 09:35 PM

If it is blowing hot air in vent mode then it is the so called Evens Valve. Either it is bad or it is being told to pass hot water to the heater core by the dash switch.

pkmesser · 07-13-2011, 09:56 PM

Quote:

Originally Posted by Full-Timers

If it is blowing hot air in vent mode then it is the so called Evens Valve. Either it is bad or it is being told to pass hot water to the heater core by the dash switch.

That is why I posted to check the heater hoses. Newmars have Evans brand valves, I don't know if that is the brand other manufacturers use, so I did not say a brand name. As you say, it could be the dash control switch also, in either case, if you have hot coolant going to the heater when you don't want it to, an inline ball valve, when turned off, will assure there is no hot engine coolant going to the heater.

DAN L · 07-14-2011, 03:07 AM

Quote:

Originally Posted by Full-Timers

If it is blowing hot air in vent mode then it is the so called Evens Valve. Either it is bad or it is being told to pass hot water to the heater core by the dash switch.

i replaced my vacuum operated ''evans'' heater control valve a year ago with a valve from schucks auto supply (now oreillys) mfg. by factory air, pn 74612. it works very well. ims, it cost <$10.

pkmesser · 07-15-2011, 10:44 AM

Quote:

Originally Posted by DAN L

i replaced my vacuum operated ''evans'' heater control valve a year ago with a valve from schucks auto supply (now oreillys) mfg. by factory air, pn 74612. it works very well. ims, it cost <$10.

Mine, an Evans Tempco, is electric, and as mentioned is $130.

Full-Timers · 07-15-2011, 09:50 PM

Adding a ball valve inline with the heater hose is a good solution for AC use if you have a bad “Evans” valve. However, if you have a bad “Evans” valve and open the ball valve for heat you will have full hot with no control. The correct solution is to replace the “Evans” valve. I replaced mine 6 years ago and have had no problem with it since. They did admit at the time they had a bad batch and replaced it for free.

az bound · 07-16-2011, 05:10 AM

If its a P32 chassis I would suspect ether the The Evans tempcon valve or the rheostat on the dash temperature control.
To check the rheostat turn the ignition to the on position and rotate the temp. control knob and observe wheather or not the evans valve is operating. It moves very slowly.
To check the evans valve bring the engine to normal operating temp and with the dash temp control set to the coolest setting, feel the hose on the outlet side of the evans valve. If it is hot the valve is the problem. www.evanstempcon.com

PeterB · 07-16-2011, 08:19 AM

Wow, thanks all for the information...should be very helpful. Where would the "evans valve" be located? It sounds like this valve makes sense. The problem happened immediately, one minute I was thinking of turning the A/C down since it was a bit chilly then wham...hot air. If it was a leak it would be a gradual loss of cooling I would think. I get hot air on every setting of the temperature control even in the vent mode. I will check this out tonight, we have a trip next weekend and the forecast is for hot weather so getting this fixed would be great. The only saving grace was being able to run the generator and use the ceiling A/C...always nice to have a backup plan!

Thanks!

Peter

az bound · 07-16-2011, 09:28 AM

The valve is usually located directly above the dipsticks for the transmission and engine. It will be on the the heater hoses running to the core.

pkmesser · 07-16-2011, 11:53 AM

Quote:

Originally Posted by Full-Timers

Adding a ball valve inline with the heater hose is a good solution for AC use if you have a bad “Evans” valve. However, if you have a bad “Evans” valve and open the ball valve for heat you will have full hot with no control. The correct solution is to replace the “Evans” valve. I replaced mine 6 years ago and have had no problem with it since. They did admit at the time they had a bad batch and replaced it for free.

Not true in my case so far, the Evans valve controls to a great extent, it just does not shut off completely.