Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 11, 2025 ...

Dash Air

August 01, 2017, 02:47:43 pm

Dash air working great but cannot switch from defrost to dash or floor operation.  Any ideas would be welcomed.

Quote Selected

Re: Dash Air

Reply #1 – August 01, 2017, 03:08:40 pm

The dash dampers work on vacuum. Sounds like your vacuum pump may not be working. With no vacuum it will default to defrost.

Quote Selected

Re: Dash Air

Reply #2 – August 01, 2017, 03:12:12 pm

Ours is under the front step.  Cheaper to replace with electric than a new air driven pump.  It could just be a leak.  Our tin can vacuum reservoir was starting to rust.  Or a bad hose.

Search for vacuum pump.

Rich

Quote Selected

Re: Dash Air

Reply #3 – August 01, 2017, 06:29:07 pm

Yup, the dash HVAC vent system works on the 12 VDC vacuum pump.

Default position is DEFROST.

There are a lot of 12VDC electrical vacuum pumps out there.  Example, all Ford PU diesel have them!

Start by checking if the vacuum pump is working.  If not, check for power to it.  If it is working, check for a leak between the pump and the dash control.

Quote Selected

Re: Dash Air

Reply #4 – August 01, 2017, 06:43:18 pm

They are not all electrical. Mine is still air powered.

obsolete vacuum generator

Quote Selected

Re: Dash Air

Reply #5 – August 01, 2017, 07:58:29 pm

Your vacuum pump[ should be mounted to the firewall in the front that you access when you remove the front grill.

Quote Selected

Re: Dash Air

Reply #6 – August 01, 2017, 11:25:58 pm

Remove the front grill, the pump is located on the drivers side below the AC condenser. Turn the ignition key on, you don't have to start the engine. You should be able to hear the vacuum pump run for 10 or 15 seconds and shut off IF the vacuum switch is satisfied..

If it does not run, check the relay on the firewall directly above, you can temporarily jump out the relay to see if the relay or contacts are bad. You really need a Volt meter to insure you have 12 v to the pump.

If the pump runs? Does it cycle on and off every few minutes? If the pump is working then you need to check the black hose going thru the firewall to the AC control box for vacuum.  I found that it takes a little over 6 " vac to overcome the spring on the defrost damper. SO...... low vacuum will act like NO vacuum and the air will only blow out the defrost vents. With a gauge you can also adjust the "cut in" and "cut out" settings that are located on the back of the vacuum switch.



Mine had the same symptoms as yours and I eventually found that I had an internal leak in the AC controller, found one identical to it out of a 94 chrysler New Yorker. After taking my old unit apart I think I could have fixed the leak with some silicone grease on the small hose connections to the controller and the push button slides. That's a project for another day, but it would be nice to have a spare on hand.

Quote Selected

Re: Dash Air

Reply #7 – August 02, 2017, 01:54:12 am

Donnie.
 Welcome to the 1995 U280 36' Unihome club.
  Isn't it handy to be able to remove the front panel and access al the front end gadgets.    At least your AC works, ours needs a compressor and a ruptured hose replaced I think. The repair is very close to the top of the list.

Just finished a direct water fill project, see level tank monitor and engine coolant flush.  Now I'm just waiting for it to get a little warmer,    102 today and 112 tomorrow:😜

Quote Selected

Re: Dash Air

Reply #8 – August 03, 2017, 04:58:51 pm

Thanks everyone for your responses.  All is ok, the hose came off, probably over the rough roads we hit in Quebec and New Brunswick.

Quote Selected