Double trouble on Adventure 34' Pusher

[BlueLine]

Just purchased a 99 34' Pusher 275 Cummins on Freightliner frame. First problem is speedometer. Speedo has a 30mph error compared to GPS, where do I look and what do I look for to remedy problem. Also Cab ventilation control seems to be stuck on defrost. No matter what I do the AC won't come on nor can I get air to switch to vent or AC or Max AC

[cbeierl]

Is it possible that the speedo is displaying KM instead of MILES?

[ernieh]

I believe that the heater/ac defaults to defrost. Check the vacuum pump and associated plumbing.

[BlueLine]

Went out and checked speedo, this unit does not have a select for MPH/KPH, it has the double indication printed on the face of the speedo. Thanks for the quick return, still look'n.

[BlueLine]

Thanks ernieh, I'll go out and retrace plumbing from the back of selector. I did see a couple of vacuum cans mounted in the forward compartment. I'll keep you posted on my progress, thanks for the direction.

[Martind4]

Are you sure you don't have the option to display Kilometers and Miles? Your rig is only 1 year older than ours and I think you have the VDC (vehicle data computer) dash. On ours, the odometer reset button doubles as the switch from Km to miles, press and release quickly resets the odometer and press and hold will switch to Km or miles.

[BlueLine]

You were absolutley right. I hit the reset and it changed the trip meter to "0", then held it for several seconds, but nothing was indicated in the window. However I drove the vehicle and was elated that it was reading correctly. I was expecting the window to give an indication of MPH or KPH, but it didn't. Thank you for the advise and direction. Problem solved lesson learned.
Travel Safe,Travel Often.

George & Barbara
And the Three Amigo's (Chihuahuas)

[BlueLine]

Ernieh, You know your stuff. Accurate diagnosis. I took your information and augmented it with some old posts and photos on vac problems. Traced out the system from behind the selector: Red, White, Yellow, Black, Blue and Green. Found last foot of Blue tubing chaffed near cannister connection. I cut off the connection to the cannister and slipped a 12 section of 1/8" clear tubing over the chaffed Blue line and sealed the selector control end. Reconnected to the cannister and I'm up and running again. Thanks, this site and RV savy people such as yourself are the best tools I can have for keeping me on the road, and you can't beat the price,
Thanks again.
The other George & Barbara and the 3 Amigos (Chihuahuas)