Dash Air runs single speed

[Craig L]

Hi, we have an 08 holiday rambler caspian IV the dash Air only blows one speed, does anyone know if it’s the blower relay switch that usually fails, or the control switch itself located on dashboard on dash that fails?

[K7JV]

Not knowing how your system is controlled, I can only offer past experience. On many rigs, our '06 Dynasty included, there is a resistor module mounted in the plenum of the dash A/C and heating core unit that has typically four wires connected to it, either individually or via a molded plug on the end of a cable. When those resistor modules fail, a single speed is the result. It will likely be easily visible behind your front access opening, under the windshield, and mounted with a couple of screws to the molded HVAC housing. You can pull it and take it to NAPA or O'Reillly's and probably find your replacement. On our coach, it is a Ford Motorcraft module.

[Jeff753]

If it’s stuck on high it’s likely the resister at the air box. I think I read they fail to high. If it’s stuck on another speed it’s probably the dash switch.

[slowmachine]

Good explanation here:

http://www.resistorguide.com/applica...ower-resistor/

[nehog]

Some designs have a separate fuse for the highest speed. So if the lower speed fuses blows, then only the high speed works. I guess knowing which speed is working would help.

IMHO: the resistor pack is bad. Many have a non-resettable thermal fuse that can blow, in addition to connections that fail, and resistors that open.

[distaff]

I just had mine replaced - as is not uncommon on my coach it was not located where it should have been or where it normally is but we had to cut a hole in the fire wall and dig through all the spray in foam.

I lost the picture of it that I took with the part number, but it was a discontinued Motorcraft part that seems to be getting very hard to find. If you find a source please post it.

[Outbound]

Ditto on bad resistor. Good luck

[Skidaver]

Mine was stuck on high. Ordered thermal fuse from Radio Shack and replaced the failed one in the resister module per instructions I found elsewhere on this site. Worked like a champ but failed again. My blower is making a lot of noise and presumably running slow, which caused the thermal fuse to fail again (I think). Sorry I can't help you with the part number for the thermal fuse but you should be able to find it with a search of the forum. Otherwise, the new module probably comes with one. The thermal fuse was probably $2 and the module $35, something like that.

[MSHappyCampers]

Hi Craig! Welcome to IRV2! We're sure glad you joined the gang!

Sorry I can't help with that.

Good luck, happy trails, and God bless!

[davkevmat]

Mine only runs on high and I assume it is a bad resistor block. Does anyone know where it would be located in a 98 diplomat. I prefer to not dismantle the whole front of the motor home looking for it.

[DennisZ]

Originally Posted by davkevmat

Mine only runs on high and I assume it is a bad resistor block. Does anyone know where it would be located in a 98 diplomat. I prefer to not dismantle the whole front of the motor home looking for it.

Dave
The resistor pack should be located in the air plenum in the front of the motorhome near the air conditioning lines are, it needs to be in an area of air flow for cooling.

Here is a picture that may be close to what yours is, mine is in about the same location.

[8.3Oilbuner]

Good morning to all; As I post this, I have not checked to see if these part numbers are still good, so here goes. Resistor pack, Ford part# D8BH-19A706-AB or D32H-19A706-AB. Could be a while ago but showed NW RV Supply in Eugene, Or. had them for $19.85. Should be able to match up at any parts store. Had to replace in my previously owned 2000 Monaco Windsor and my, new to me 2001 Monaco Windsor. Hope this info helps. Good luck!

[davkevmat]

Thanks for the information I will go look a little closer this morning. If I can find it I will take it out and the part numbers and head to NAPA first.