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Over the Road AC not working properly

Yahoo Message Number: 23934
I experienced a similar OTR AC problem while returning from JC with the new (for me) coach.
When the outside temp hit about 93-95, the temp of the air coming out of the AC started dropping. As the outside temp went further up, the OTR AC got warmer and warmer... The fan works fine, it just blew warmer air.
When I started the generator and got the house AC working, the OTR AC began to blow cooler air.
I hit temps at 109 in Redding, Ca and 104 in Bakersfield. At least there was Flagstaff, which was nice. Even Texas wasn't that hot (relatively).

Ideas?

David

Re: Over the Road AC not working properly

Reply #1 –
Yahoo Message Number: 24105
Quote from: David Cole \[br\
]
I experienced a similar OTR AC problem while returning from JC
with the new (for me) coach.



Quote
Ideas?

David
David, I have developed a problem with my dash air that may or may not be the same as yours, but is easy enough to check.
I believe my heater control valve is letting hot engine coolant into the conditioned air path (think "heat turned on"). I have determined this by measuring the eyeball duct temperature when first turning on the dash air and letting it stabilize; turning the heat control knob to hot and back to cold, and watching the temperature plummet. I have to do this every time I restart the engine, but it works every time.

The first time I did it, the duct temperature went from a steady 80 degrees to a steady 56 degrees.
Jay

05 Inspire daVinci 51457

Re: Over the Road AC not working properly

Reply #2 –
Yahoo Message Number: 24106
Jay,

Mine seems to be related to the interior temp of the coach...but who knows what's causing it?

Thanks.
David

Re: Over the Road AC not working properly

Reply #3 –
Yahoo Message Number: 24116
David, have you checked the passenger side temp control? I found that if it is still on heat, it will override the driver's side and prevent cooling.

Walt Rothermel

03Allure30811 --still for sale

Re: Over the Road AC not working properly

Reply #4 –
Yahoo Message Number: 24117
That was cranked to freezing...I'll look again, but I did look there.

David

Spiker1029@... wrote:

Re: Over the Road AC not working properly

Reply #5 –
Yahoo Message Number: 24133
David

I would suspect the Heater Control Valves (HCV), one for DS one for PS. These are motor driven ball valves which modulate the flow of hot water when you diddle the DS or PS temp. knobs. When they get blocked or malfunction they seem to be on constant "HOT". If you can rap on them with a tool handle, you might dislodge whatever is blocking it.... Otherwise, replace 'em.

Joe On-The-Road in Deer Lodge, MT '04 Allure 36' #31031

Sign up to receive e-mail copies of our OTRA (On-The-Road-Again) reports describing our adventures as we travel the U.S. and Canada in our RV. Send me an e-mail at: joe@... ..... or view past reports and trip statistics on-line at: http://www.pehoushek.com/RV/r-ving.htm

Re: Over the Road AC not working properly

Reply #6 –
Yahoo Message Number: 24137
Hi Folks,

When the dash A/C doesn't work, there are 3 systems involved to investigate: the electrical, the cooling and heat, and the vacuum.
The vacuum controls the dampers and the H valve for heater coolant flow. The dash control, vacuum motors(servos), reservoir, pressure switch and vacuum pump make up this system. The plumbing is by SCS/ Frigette, Ft Worth, TX and found in master service manual, vacuum diagram, p. F12. Wiring diagram #S0695 is for the electrical part which shows the dash controls and wiring.
The cooling system includes the engine a/c compressor and clutch, the condensor coils in the radiator compartment and the hi-lo pressure switch in the engine compartment, the wiring for which is found in #S0699(foldout), the two hoses to the front dash evaporator coils and fan.

If the vacuum pump pressure switch fails - control of the H valve for heater fluid flow is lost. Some folks in the past have reported success in replacing the switch. If there is a refrigerant leak, the hi-low pressure switch will prevent the compressor from engaging.
Fuses, interconnects and relays are always suspect if nothing else is wrong (see #S0695.02).

My failure was a hole at one connection to the condensor coils due to rubbing on the attaching bracket.
Fred Kovol
The

Quote from: Joe Pehoushek
>

David

> I would suspect the Heater Control Valves (HCV), one for DS one for

PS.

Quote
These are motor driven ball valves which modulate the flow of hot

water when

Quote
you diddle the DS or PS temp. knobs. When they get blocked or

malfunction

Quote
they seem to be on constant "HOT". If you can rap on them with a

tool

Quote
handle, you might dislodge whatever is blocking it.. Otherwise,

replace 'em.

Quote
>

Joe On-The-Road in Deer Lodge, MT >

'04 Allure 36' #31031

Sign up to receive e-mail copies of our OTRA (On-The-Road-Again)

reports

Quote
describing our adventures as we travel the U.S. and Canada in our

RV. Send

Re: Over the Road AC not working properly

Reply #7 –
Yahoo Message Number: 24151
I have found the folks at SCS Frigette to be very helpful and great to work with, both on this coach and my SOB.
A Call to their tech people will go a long way to solving this prob.
800-293-5313

ddtuttle

2000 Allure #30443