Operation of front heat/ac

[Slojoe72]

Looks like the hvac panel is all electric and no cables. I was wondering how it works. Is there a heater core up front, or in back.... Ect.
2 problems I have .... Blower only works on high, and no heat. Only cold air comes out. I know in a car the blower speed is controlled but a resister that regulates voltage going to the blower motor to control fan speed. Just don't know if the same.
1999 holiday rambler imperial 40'

[Slojoe72]

Thank you guys for all the input. I'll get checking and let you know what I found.

[JimM68]

The dahs HVAC is a box under the pass side of the dash, probably accessible if you open the front hood as if to get to the genny.

The speeds will be a resister pack similar to a car setup.

The always cold will be one of two things.
There will be a shutoff valve in a heater hose, probably electric, possibly mechanical. Feel the heater hoses, see if they get warm.

There will also be a "blend valve" similar to what is in a car, it controls how much air passes thru the heater core vs how much goes around it.
Then blend valve could be cable controlled, or DC stepper motor, or even a vacuum motor.

[Slojoe72]

Thank you guys ..... Ill start looking deeper

[Bikeboy57]

The heater core is up front, and so is the fan. You have correctly diagnosed your problem. It's two or three resistors that step down the DC voltage to give you lower speeds.

I have no idea where you might find the resistors, but they are usually found somewhere in the air flow so that the blowing air keeps them cool. Find the blower, and find the electrical connection. You will probably find the resistors there. Also look for a fusible link there. Some have a high temperature fuse in series with the resistors to prevent a fire. The can blow out.

Good luck and report back what you find.

[10forty2]

For the blower, it's probably the switch as has been stated. For not having heat come out...it could also be a stuck valve in between the radiator and the heater core not allowing hot water to enter the heater core. My coach has a manual 1/4-turn valve in the line before the heater core (installed prior to my ownership) that has to be turned to allow hot water to enter the core. It must be turned off in the summer to get air conditioning to work properly. The OEM setup was automatic and was controlled by the dash controls, but apparently failed at some point and was replaced by what I have now. I'm probably going to replace that manual valve with an electric valve that I can control from inside the coach so I can change it when I want to and not have to raise the hood.

[jerseyjim]

As far as the fan only working on "high", that is probably just the switch itself. Burned out due to wear and/or age. Had that in one of my cars...dealer cost me 100 bucks. And the switch itself was "nothing" plastic. But...I needed it, they had it...so there it is.
As far as keeping warm, some folks use the furnace when traveling (check your propane), or to keep cool, if you have a generator, turn on the roof a/c units when traveling.

GATORCQ is right. (maybe the core is clogged. That= replacement)

[gatorcq]

Most Class A's have 3 systems
1) A Dash AC system / heater - just like a car. AC compressor mounted on engine. A heater core up front which derides it hot water from the radiator. For reference see http://www.acmeairparts.com/

2) Qty 2 Roof top AC unit or a basement AC unit which consists of 2 compressors.

3) Propane heater.

[AstroRig57]

I'm sure people aren't quite sure what you're asking. Can you start off by writing complete sentences and filling in the gaps? There's no limits on words or characters so there's no need for some type of shorthand.

[Slojoe72]

I'm cold ....... Help?